Holroyd Precision Ltd

Centre for Compressor Technology

Compression and expansion technologies in future energy systems, from idea to the customer.

The Centre for Compressor Technology offers world leading research and development of twin screw machines and other rotary positive displacement compression and expansion technologies. The Centre is the hub for scientists, engineers and industrial experts to work together and solve some of the biggest challenges for compressor industry in energy utilisation.

About the centre
Research
Projects
Potential PhD projects
People
Facilities
Publications

About the centre

Our vision

To extend the boundaries of understanding of rotary positive displacement machines for compression and expansion processes, thereby:

enabling them to operate more efficiently over a wider range of conditions, with aim to achieve Net0 2050 targets by reducing both environmental impact and manufacturing costs;
utilising such machines in novel energy systems and improved recovery of power from low grade heat;
serving as an aid to industry in the research, design, manufacture and operation of such machines, both in existing and novel forms.

Expertise and capabilities

Funded by industrial contracts and public funding, members of the centre have developed software for improved modelling of both compression and expansion processes, the use of computational fluid dynamics for more detailed studies, including solid-fluid interaction and noise reduction and state-of-the-art test facilities for both air and refrigerant compressors and detailed internal flow measurements.

Apart from its ongoing research activities, the centre is able to investigate and solve industrial problems, offer courses in machine design both to registered students and industrial engineers, license proprietary software and, if required, carry out the complete design, build and testing of prototype machines for industry. We are proud to be closely working with Royal Academy of Engineering and major compressor companies on strategic research projects such as SECRET which is set to make a step change in future oil free compression technologies.

Additionally, the centre organises and hosts a biennial International Conference on Compressors and their Systems, which is sponsored by the Institution of Mechanical Engineers (IMechE), the Institute of Refrigeration (IOR) and leading industrial manufacturers. This has been functioning since 1999 and is a leading forum for academic, research and industrial organisations concerned with the development of fluid machinery.

Centre members have been granted 12 patents, published three monographs, over 100 journal papers, over 200 conference publications and over 200 industrial reports, for which they have received 14 professional awards and prizes.

Key research activities

Rotor profiling and screw machine performance calculation
Fundamental research in leakage mechanisms in rotary positive displacement machines
Utilisation of low temperature heat sources by using screw expanders
Research in multifunctional and internally geared screw machines
Multistage screw compressors for high pressure difference applications
Computational fluid dynamics (CFD) in screw machines
Laboratory investigation of screw machine working processes
Investigation of multiphase and leakage flows in screw machines
Noise in rotating machines
Multiphase flow modelling and experimentation

Services offered

Fundamental and applied research in positive displacement machines
Project evaluation and feasibility studies
Software development
Fault investigation
Thermodynamic and fluid flow studies
Stress analysis
Instrumentation and control
Laboratory measurements
Noise suppression
Complete product design and development

Software program suites

SCORPATH – Screw Compressor Optimal Rotor Profiling and Thermodynamics
SCORG – Industry leading software for design and analysis of screw machines
DISCO – Design integration interface for Screw Compressors

History

Following three years of collaborative work between Professor Ian Smith, who was attempting to develop screw expanders, for recovery of power from low grade heat, at City, University of London, and Professor Nikola Stosic of the University of Sarajevo, who had significant experience in the development of similar machines as compressors, the centre was established in 1995, when Nikola Stosic was awarded a Royal Academy Professorship, with industrial co-sponsorship by Holroyd, of Milnrow, Lancs.

Professor Ahmed Kovacevic, who had been working on screw compressors since 1986, joined them in 1996 and pioneered the application of Computational Fluid Dynamics to evaluate the screw machine performance. Following success in collaboration with industry, in 2020 prof Kovacevic was awarded Royal Academy of Engineering Research Chair in Compression Technologies with industrial co-sponsorship by Howden Compressors of Glasgow.

The Centre was joined by Dr Elvedin Mujic, who made a significant contribution to noise reduction and who now holds a senior position in industry, and subsequently by Dr Ashvin Dhunput, who also now holds a senior industrial position. More recently, they have been joined by Dr Matthew Read now a lecturer in the School of Science and Technology. He makes a significant contribution to integrating expanders into power recovery. Dr Sham Rane joined the Centre in 2011 and since then has made significant advances in CFD modelling of rotary positive displacement machines. The newest additions to the Centre are Dr Thibaud Plantegenet, an expert in tribology and bearing technology; Mr Aleks Krupa our guru in electronics and measurements and Ivona Ivkovic-Kihic, a computer scientist who is working as research project coordinator in the Centre.

Featured profile

Professor Ahmed Kovacevic

Research

Case Studies

CERES: Industrial Consortium for Compressors and Expanders in futuRe Energy Systems

Through the Industrial Consortium, City’s Centre for Compressor Technology provides a forum for industry and academia to coordinate pre-commercial (TRL 1-3) research on industry-relevant compression technologies for the energy transformation sector. The industrial partners can also benefit from a tailor made service whilst fostering a broader cross-business sector understanding of compression technology developments.

Project SECRET: Smart Efficient Compression: Reliability and Energy Targets

This research project aims to improve rotating compression technology by developing methods to reduce their energy consumption, the impact on environment and improve their reliability. The project is conducted in collaboration with the UK-based industrial sponsor.

Research Projects

The most important contributions from the Centre in research and knowledge transfer in compression and expansion technologies are:

Patents for the “N” rotor profile in 1996 and 2013. The “N” rotor profile is now the industry standard and has generated significant income for City.
Trilateral Flash Cycle and Wet Steam Cycle for improving the efficiency and reducing the cost of power recovery from low grade heat sources.
Four fully equipped state-of-the-art laboratory test rigs for compressors and expanders, built to meet highest industrial standards.
Holding a Royal Academy Chair in Positive Displacement Compressor Technology between 1995 and 2000.
Howden Chair in Engineering Design and Compressor Technology from 2008 until 2020.
Royal Academy of Engineering Research Chair in Compressor Technology with industrial co-sponsorship from Howden, 2020-2025
Supporting Electratherm, Reno, Nevada, USA 2005-2015 in their development and marketing of screw driven Organic Rankine Cycle (ORC) systems for waste heat utilisation.
Establishing Heliex Power Limited in 2009, as a spin out company from City, University of London for use of steam driven screw expanders for waste heat utilisation.
Postgraduate and industrial courses in Mechanical Engineering at City, University of London, providing a Master of Science education to more than 300 young engineers in screw machine technology through the unique theory and laboratory courses.
PhD students have been supervised by centre members, leading to their successful doctoral grades in area of Thermodynamics, Fluid Mechanics, Computational Fluid Dynamics, Metrology and Tribology in positive displacement technology.

Selected funded research projects

Principal investigator.	Co-investigators	Project title	Funder	Amount awarded to City (excluding partners)	Start date	End date (including no-cost extension)
Professor Ahmed Kovacevic	Dr Matthew Read Professor Nikola Stosic	Ammonia Screw Compressor Bearing Technology	Mayekawa Manufacturing Co., Ltd.	£129,999 per annum	1 May 2022	ongoing
Professor Ahmed Kovacevic	Professor Nikola Stosic	Feasibility and basic study of screw compressor for aerospace application	Triumph Group	£119,000 per annum	1 Jan 2022	ongoing
Dr Matthew Read	Professor Ahmed Kovacevic	Internally Geared Screw Compressors	Carrier Global Corporation, PDM Analysis Ltd.	£67,500 per annum	1 July 2021	ongoing
Professor Ahmed Kovacevic	Dr Sham Rane	Smart Efficient Compression: Reliability & Energy Targets	Howden, Royal Academy of Engineering	£151,956 per annum	1 September 2020	ongoing
Dr Matthew Read	Professor Nikola Stosic Professor Ahmed Kovacevic	LNG Compressor for Cryostar	Cryostar SAS	£49,000	4 Jan 2021	30 Sep 2021
Professor Ahmed Kovacevic		Jaecklin - CFD analysis - 110 kW oil injected screw compressor	Jaecklin GmbH	£39,000	2 Nov 2020	31 Jan 2021
Professor Ahmed Kovacevic		SCORG Impact case HEIF 2020-21	City, University of London	£4,200	1 Nov 2020	31 Jul 2021
Professor Ahmed Kovacevic		Mayekawa High Pressure Refrigeration Compressor	Mayekawa Manufacturing Co., Ltd.	£104,000	1 Oct 2020	31 Mar 2021
Professor Ahmed Kovacevic	Professor Nikola Stosic	Bascom-Hunter - PTG - predesign study and training	PTG	£35,000	1 Jul 2020	31 Aug 2020
Professor Ahmed Kovacevic	Professor Nikola Stosic	Kyongwon Machinery	Kyungwon Machinery	£367,151	2 Mar 2020	30 Jul 2021
Professor Ahmed Kovacevic	Professor Nikola Stosic	Feasibility study and Basic Design for 360mm COmpressor	Mayekawa Manufacturing Co., Ltd.	£99,000	9 Dec 2019	8 Jun 2020
Professor Ahmed Kovacevic	Professor Nikola Stosic	Feasibility study - Oil free compressor for Cold Harbour	Coldharbour Marine Limited	£29,000	1 Dec 2019	30 Nov 2020
Professor Ahmed Kovacevic	Professor Nikola Stosic	Improvements of Ningbo Baosi compressor and "N" rotor license	Ningbo Baosi Energy Equipment Co., Ltd.	£64,500 per annum	30 Nov 2019	31 May 2021
Professor Nikola Stosic	Professor Ahmed Kovacevic	Design of refrigeration compressors and profile license for DORIN	Officine Mario Dorin Spa	£65,700 per annum	1 Sep 2019	31 Aug 2021
Dr Gursharanjit Singh	Professor Ahmed Kovacevic	Improvement in the robustness and fidelity of the CFD methodologies for positive displacement machines	City, University of London Pump-Priming Fund	£6,052	Feb-2019	Jan-2020
Professor Abdulnaser Sayma	Professor Ahmed Kovacevic Dr Matthew Read	Fundamental Studies on Organic Rankine Cycle Expanders (NextORC)	EPSRC	£165,166 per annum	1 May 2017	30 Apr 2021
Professor Ahmed Kovacevic	Dr Sham Rane	Howden Chair in Engineering Design and Compressor Technology	Howden	£100,000 per annum	1 January 2008	31 Aug 2020
Professor Ian Smith	Professor Nikola Stosic	Optimisation of low grade heat recovery systems with screw expanders	Helix Power	£50,000 per annum	1 January 2012	30 Apr 2020
Professor Ahmed Kovacevic	Dr Nusa Fain	Integration of Marketing and R&D in New Product Development	Howden Compressors Ltd	£170,799	1 January 2011	31 December 2012
Professor Ahmed Kovacevic	Dr Nusa Fain	Brief Encounters Network: Exploring New Forms of Online Collaborative Design	Engineering and Physical Sciences Research Council	£3,559	1 March 2012	1 July 2012
Professor Ahmed Kovacevic	Dr Sham Rane	NARIP: Networked Activities for Realisation of Innovative Products	Erasmus and Strategic partnerships	€87,420	1 October 2014	30 September 2017
Professor Ahmed Kovacevic	Professor Nikola Stosic	Grid generation for variable screw rotor geometry - Funds for PhD research for Sham Rane	Maya Engineering Works, India and City, University of London	£15,000 (Maya) £30,000 (City)	1 September 2011	30 September 2014
Professor Nikola Stosic	Professor Ahmed Kovacevic	Dynamic behaviour of compressor system in unsteady operation - Funds for PhD research for Ekaterina Chukanova	Greenleaves International LLC, Oregon, USA and City, University of London	£15,000 (Greenleaves) £30,000 (City)	1 September 2011	30 September 2014
Professor Ahmed Kovacevic	Professor Manolis Gavaises	Multiphase flow in the suction of screw compressors	Compressors Centre, Cavitation Centre, Overheads AK	£78,000	1 January 2012	31 December 2015
Professor Ahmed Kovacevic	Professor Nikola Stosic	Thermal management of clearances in screw compressors	Howden	£5,000 fees £28,000 through various projects	10 April 2010	30 September 2015
Professor Nikola Stosic	Professor Jamshid Nouri	Experimental investigation of flow in screw compressors by LDV	EPSRC	£220,000	1 May 2005	31 May 2005
Professor Ahmed Kovacevic		Multiphase pumping systems	DASS Motors, Canada	£55,000	1 May 2007	1 May 2008

Featured profile

Dr Matthew Read

Projects

“N” rotor profile

The City “N” profile has been developed as a result of 30 years' research and development in screw compressor technology and world patents are held on it. It confers the following advantages over other profiles:

Greater flow area for a given rotor diameter
Smaller leakage area
Stronger gate rotor lobes, which reduces lobe deflection both during manufacture and operation
Involute form on the contact band, leading to nearly pure rolling relative motion between rotors
Lower rotor contact forces without the risk of “rotor rattle” through local torque reversal
Avoiding seizure in the event of rotor direct contact.

"N" rotor profile diagram. View full-size image.

Expanders

Two-phase process lubricated screw expander on test rig. View full-size image.

Expanders have a variety of applications but for positive displacement machines, their biggest potential is for two-phase processes where they may be used to replace throttle valves and for large scale power recovery from low grade heat sources.

The centre holds vital patents on the use of any type of positive displacement machine for this purpose and has developed low cost, process lubricated twin-screw expanders with adiabatic efficiencies greater than 75%; the highest value ever attained in a two-phase expansion process.

Machine design

Given the required performance data, the centre offers full design services either for a complete compressor or expander, or for rotor and porting only, given the details of the machine. The output is then delivered to the customer in the form of drawings, which are also accessible electronically from a secure site.

The centre is also able to arrange prototype manufacture and has test facilities complying with full international standards for the testing of air and refrigeration compressors.

SCORG

Industry-leading grid generation and performance prediction software for positive displacement screw machines.

The first version of the SCORG software was originally developed by scientists working at City, University of London. PDM Analysis Ltd is exclusively licensed by City, University of London to continue the development and implementation of SCORGTM. City, University of London welcomes PDM Analysis Limited’s commitment to commercialising SCORG for the benefit of society.

Today City and PDM Analysis are the market leaders in providing solutions for the analysis and design of screw machines.

SCORG alto

SCORGTM alto is a cloud platform hosted in Microsoft Azure, enabling design and analyse screw machines using the software SCORG. With SCORGalto you can access greater capacity to produce high-fidelity simulations, with greater security and complete support from our experts.

SCORPATH

The centre has developed an extensive range of software to aid the design of compressors, which is continually being upgraded. The main package is known as SCORPATH (Screw Compressor Optimum Rotor Profile and THermodynamics). Starting from the specified compressor duty and the minimum number of assumptions, this program determines the optimum machine geometry and rotor profile to obtain the desired results. The output includes full details of the rotors and their porting which can be imported directly into a CAD system, together with performance predictions, bearing loads and suggested choice and details of the tool profile required to manufacture the rotors. User licences are available for this package.

Screenshot from the SCORPATH software. View full-size image.

Download the software

Computational Fluid Dynamics and Analysis

Computational Fluid Dynamics (CFD) is widely used today as an aid for optimising the design of fluid machinery. However, due to the complexity of the geometry and other associated problems, this analytical tool was not used for screw compressors.

The centre has developed SCORG (Screw Compressor Rotor Geometry), a grid generator, together with associated supporting functions, which enables screw compressor flow and performance to be estimated when attached to commercial CFD and CCM (Computational Continuum Mechanics) solvers. In the latter case, solid-fluid interactions can be estimated so that component distortion and its effect on compressor or expander performance can be estimated.

As in the case of SCORPATH, user licences are available for this software package.

Screenshot from the SCORG software. View full-size image.

Use within industry

Reference list of major industrial users of the centre's research, advisory and design services:

Company	City / State	Country
AC Compressors	Appleton	United States of America (USA)
Aerzener	Aerzen	Germany
Agroholodmash	Izhevsk	Russia
Airplus	Inchoon	Korea
Arsenal	St Petersbury	Russia
Atmos	Charst	Czech Republic
Avtovaz	Togliatti	Russia
Azti Tecnalia	Sukarrieta	Spain
Bitzer	Singelfingen	Germany
Carrier	Syracuse, New York	USA
CFX	Berlin	Germany
CMP Corp	Oklahoma City, Oklahoma	USA
Comoti	Bucharest	Romania
Dalian Refrigeration	Dalian	China
Dass	Edmonton	Canada
Dresser-Rand	Wakefield	United Kingdom (UK)
Drum International	Bradford	UK
Dunham Bush	Havant	UK
Duynie Holding BV		The Netherlands
DV Systems	Barrie, Ontario	Canada
Eaton Compressors	Clayton, Oklahoma	USA
Edwards Pumps (Atlas Copco)	Burges Hill	UK
Electratherm	Reno	USA
Elgi	Coimbatore	India
Elthom	Nicosia	Cyprus
Fairchild Controls	Frederick, Maryland	USA
Frascold	Milan	Italy
Frick-India	New Delhi	India
Gardner Denver	Quincy, Illinois	USA
GE Global Research	Munich	Germany
Geodynamics	Brisbane	Australia
GHH (IRCO)	Oberhausen	Germany
Goodrich	Birmingham	UK
Helix	East Kilbride	UK
Holroyd	Milnrow	UK
Howden	Glasgow	UK
Jaecklin Gebr GmbH	Augsburg	Germany
JYC	Seoul	South Korea
Kirloskar Pneumatic Co Ltd	Pune	India
Knorr-Bremse	Siren	France
Komsan	Istanbul	Turkey
Korea Inst Research		South Korea
Kyungwon Machinery	Siheung-si	South Korea
Magnum Powers	Oregon	USA
Mahle Powertrain		UK
Mainstream Engineering	Rockledge, Florida	USA
Mayekawa (MYCOM)	Tokyo	Japan
Mayekawa (EUROPE)	Glasgow	UK
Measuring Specialities	Hampton	USA
Ningbo Baosi	Baosi	China
Ormat Turbines	Yavne	Israel
Pars		Iran
Powertrain Ltd	Shoreham	UK
QinetiQ	Farnborough	UK
Refcomp	Milan	Italy
Rolls Royce	Indianapolis, Indiana	USA
Rotary Compressor Systems		Switzerland
Rotorcomp	Munich	Germany
Shell	Thornton	UK
Sullair	Chicago	USA
Svenska Rotor Maskiner (SRM)	Stockholm	Sweden
Tamrotor (GD)	Tampere	Finland
TDI	Aarhus	Denmark
Termomeccania	La Spezzia	Italy
Trane (IRCO)	La Crosse, Wisconsin	USA
Triumph Group	Connecticut	USA
Trudbenik	Doboj	Bosnia and Herzegovina
Tutthill	Springfield, Montana	USA
Vmac	Nanaimo	Canada
VMC Italia	Creazzo	Italy
Whipple	Sacramento	USA
Wilksch Airmotive	Buckingham	UK
Wittig (GD)	Schopfheim	Germany
Wuxi	Wuxi	China

Featured profile

Professor Nikola Stosic

Potential PhD projects

Potential PhD Topics

We invite high-calibre students with a passion for research to join us and study for a PhD. Potential PhD topics are outlined below. If you are interested in one of these, please contact the named supervisor or Dr Yan Youyou, Senior Tutor for Research in the School of Science and Technology. Note that there is no funding attached to these topics: applicants must make separate arrangements to fund their studies.

Full details of the application process are available online. On your application form, please state that you wish to be considered for admission to the Centre for Compressor Technology, Department of Engineering.

Evaluation of bearing technology for screw compressors

Supervisor: Dr Matthew Read

Bearings are a key component of rotary positive displacement machines, where both axial and radial loads must be supported. There are a range of bearing types available, with rolling element and hydrodynamic most commonly used. Other technologies used in higher specific speed applications such as turbomachinery include hydrostatic, magnetic and foil gas bearings. This project will aim to characterise the speed, load, and space requirements of bearings for screw machines. The working fluid/lubricant is an important consideration, and the use of bearing types is constrained due to cooling and lubrication requirements.

Objectives:

Review state of the art for bearings across a range of rotating machinery applications
Characterise constrains for screw compressor bearings across a range of scales, working fluids and operating conditions
Investigate influence of bearing selection on design and operating parameters such as operating speed, clearance gaps and drag losses

Lubricants for oil-injected positive displacement machines

Supervisor: Prof Ahmed Kovacevic

The aim of the of the proposed research project is to set criteria for defining new carbon neutral lubricants for positive displacement machines and develop requirements and tools for selecting lubricants for new generation of environmentally friendly positive displacement machines. The objectives are:

Review state-of-the-art literature on lubrication and lubricants in positive displacement machines and specify critical parameters which should be investigated for carbon neutral lubricants for PDM’s
Develop analytical and numerical tools to evaluate manufacturability and application of novel lubricants for manufacturers and users of these lubricants for carbon neutral oil injected positive displacement machines.
Validate the developed tools by extensive experimental investigation on a typical oil injected air screw compressor.

Materials and manufacturing methods for future screw machines

Supervisor: Prof Ahmed Kovacevic

Screw compressors are used in variety of applications which include compression of aggressive gasses, high pressure and high temperature applications, dry running conditions, water vapour compression etc. Rotors of such machines are mostly manufactured using classical machining methods including hobbing, profile grinding and milling. They are mostly produced from carbon steel, in some cases covered by protective coats. Materials such as stainless steel or aluminium are occasionally used to protect material from degradation. Despite considered to as mature technology, little research has been invested in exploring materials and manufacturing techniques for future efficient and reliable positive displacement machines. With the advent in manufacturing methods and material science, there are possibilities to make rotors of positive displacement machines, in particular screw compressors, lighter and more resistant to environments and operating conditions. In addition, it would be interesting to find possible methodologies to introduce microscopic surface features and new rotor profiles using suitable modern manufacturing techniques and materials. The success of such application will depend upon economical and technical feasibility for rotating positive displacement machines such as screw compressors and expanders. The focus of the research should be towards applications of water injected screw machines and protection from corrosion caused by applications of aggressive gasses and vapours. Materials which could be evaluated should include polymers, ceramics, materials suitable for sintering, printing, dye casting and extrusion manufacturing methods.

The objectives of the proposed pre-competitive research project are:

Review available literature and the state-of-the-art materials and manufacturing methods for application in screw compressor and expanders
Develop analytical and numerical tools to evaluate manufacturability and application of novel manufacturing methods and materials for intended applications of screw compressors.
Design and manufacture of prototype rotors and casings for advanced efficient and reliable screw machines and validate developed analytical and numerical tools.
Experimentally investigate possibilities and advantages and disadvantages of new materials for a new generation of screw machines

Artificial Intelligence tools for accelerated performance predictions and design in compressor systems

Supervisor: Dr Sathiskumar Anusuya Ponnusami

Analysis and design of compressor systems involve tools ranging from conservative analytical methods to advanced computational techniques. Currently available tools have matured over years, leading to optimal designs of compressor and expander systems. In terms of the design, significant improvements have been made in the last couple of decades, leaving very narrow room for further improvements. In this context, the proposed project aims to exploit machine learning tools to identify further optimal compressor designs, unexplored before. One of the key design considerations in such systems is the rotor profile design and optimisation. Multiple research efforts have made to optimise the profile using iterative optimisation techniques, however, there is a limitation in terms of the parameters explored in rotor shapes. In this context, the PhD project aims to develop a set of generative design techniques for rotor profiles using a class of AI algorithms, namely Conditional Generative Adversarial Networks (CGAN). CGAN is an architecture using deep convolutional neural networks (CNN) which generates images of relevance encoded with conditions. In the current context, the images are the rotor profiles, and the conditions are the thermodynamic performance metrics of the blade profiles. Upon training the CGAN using sufficiently detailed dataset obtained using thermodynamic calculations, the deliverable will be a handy tool that can yield rotor profiles for specified metrics. The underlying vision of this first step of a series of explorative studies is to close any gap in the optimality of current state-of-the-art blade profiles, while opening a new avenue of AI application in engineering systems.

Objectives: The overall objective is to realise a smart tool that yields new blade profiles with specified performance metrics and operating and manufacturing constraints. The PhD research would involve a series of research modules to realise the above objective:

Establish an automated framework for data generation involving existing state-of-the-art analysis tools (profile-thermodynamic relationships).
Develop an intelligent design platform for designing new profiles using CGAN without any recourse to usual optimisation procedures.
Train, test and numerically validate the CGAN tool, followed by experimental validation/demonstration.
Manufacturing of CGAN-derived blades and performance assessment to showcase the capability.

Numerical and Experimental Study of Leakage Flows in rotary positive displacement compressors

Supervisor: Prof Ahmed Kovacevic

Leakage flows play critical role on the performance of rotary positive displacement compressors. Such compressors today are used in refrigeration, air-conditioning, oil and gas, process industries and air compression and consume more than 20% of electrical energy generated in industrialised countries. Even small reduction in leakage flows will make significant savings and reduction of carbon footprint. To develop the high efficient screw compressor, the leakage characteristic needs to be acquired. However, the leakage characteristic is very difficult to obtain due to the complexity of geometry and process.

This PhD study will contribute to better understanding of the leakage characteristics of screw compressor by means of numerical and experimental methods. It will utilise existing compressor test rig and the numerical methods previously developed in the Centre.

Conjugate heat transfer in rotary machines

Supervisor: Prof Ahmed Kovacevic, Dr Matthew Read

Unsteady Thermo-Fluid-Solid Interaction is a common fundamental physical phenomenon in leakage flows among various rotary machines. The effect of unsteadiness and conjugation have not been extensively studied previous and potentially this could lead to inaccurate or misleading engineering design strategies. In the open literature, there is a lack of consensus in fundamental understanding of the unsteady CHT analysis methods. Multi-physics modelling tools are currently available, but still in development stage. The remaining challenges being faced include the disparity in the time scales, computational efficiency, reliability of turbulence models, etc. In most cases, there are little experimental data to validate the accuracy of modelling methodology. This research will provide a series of benchmark experimental data using LDV and PIV techniques in optical Roots blower. These data will be used to understand the fundamental physics of heat transfer in leakage flows and support further development of the multi-physics modelling and multi-disciplinary design strategy for improved energy efficiency.

Grid generation for numerical analysis of Screw Machines with Large Helix Angles

Supervisor: Prof Ahmed Kovacevic, Dr Sham Rane

Single and multiphase screw pumps usually have very large helix angles which makes it very difficult to use Computational fluid dynamics for estimation of their performance. The numerical procedures explained in literature are based on generation of the numerical mesh in a cross sectional area which follows the rotor helix and gives a good conformal mesh. However, if the rotor helix is large, the cell skewness becomes prohibitively large which introduces error in numerical simulation. This research is focused on method to develop numerical grid generation for screw machines with large helix angles to enable reliable and fast solution using generic CFD solvers. The developed methods should be validated by experimental results. The project will allow development of methodologies for evaluation of system dynamic performance, and the system nonlinear fluid-structure coupling.

Methodology for analysis and comparison of positive displacement machine configurations

Supervisor: Dr Matthew Read

There are a huge number of theoretical mechanisms which can be employed to achieve compression or expansion via positive displacement of the working fluid. Significant academic and industrial resources are spent on analysing and developing many of these to a stage where the performance can be tested and compared to the relatively small number of established machine types. There are however a small number of key geometrical performance metrics that can be used to investigate how novel concepts compare to conventional machines, thus allowing the potential benefits and drawbacks to be established at an early stage. This project will develop a robust methodology for comparing positive displacement configurations using non-dimensional groups to characterise the key performance metrics, while allowing operating constraints such as dimensions, load, and tip speed to be specified for different compressor types. A further benefit of this approach is that initial multi-objective optimisation of novel configurations can be performed using a fitness function approach based on these non-dimensional groups. This ensures a suitable basis for comparison between different machines configurations.

Objectives:

Apply dimensional analysis to identify key machine characteristics and allow comparison on a normalised basis
Use non-dimensional groups to achieve initial optimisation of a particular configuration within practical constraints such as maximum suction fluid velocity and bearing DN factor.
Verify approach using conventional machine examples (where extensive performance data is available), and apply to novel configurations

Multiphase flows in screw machines

Supervisor: Prof Ahmed Kovacevic, Dr Sham Rane

Twin screw machines are today widely used as compressors, expanders, pumps or motors in different industrial applications which either require or permit coexistence of gas and liquid in the system. These are known to be very reliable for handling clean fluids with relatively small content of liquid. To improve designs of such machine for multiphase flows of solids, fluids and gases it is necessary to fully understand flows in the inlet and internal passages. This research study will focus on experimental investigation of the suction and internal flows of such compressors by use of Laser Doppler Velocimetry in order to fully understand suction and internal multiphase flows. The study will help to develop experimental methods suitable for such investigation and will provide computational suite which will allow automated integration of measured results with the results of performance prediction obtained by numerical means which will further allow optimisation of machines for multiphase fluid handling.

Investigation of Internally Geared Screw Machines

Supervisor: Prof Ahmed Kovacevic, Dr Matthew Read

Cylindrical helical gearing profiles can allow an externally lobed inner gear to rotate inside an internally lobed outer gear while maintaining continuous lines of contact between the gears. The continuous contact between the ‘inner’ and ‘outer’ rotors (analogous to the ‘main’ and ‘gate’ rotors in a conventional screw machine) creates a series of separate working chambers. Ported end plates can be used to control the period during which fluid is allowed to enter or leave the working chambers of the internally geared screw machine. This novel configuration can be used as either a compressor or expander and has many potential advantages compared to conventional screw machines including smaller leakage paths, lower sliding velocities and more uniform thermal expansion. Research in this area can focus on a wide range of topics including:

generation of rotor profiles
investigation of viscous losses between co-rotating rotors
effect of inter-rotor and end-face leakage flows
rotor manufacturing methods
deformation of the rotors due to temperature and pressure variations of the working fluid
optimisation of machine geometry

Optimised Low Temperature Power Generation

Supervisor: Dr Matthew Read

Recent estimates suggest that the amount of heat rejected in industrial processes is greater than all renewable resources combined. The use of organic fluids in Rankine cycles has potential advantages for maximising the power generated in waste heat recovery applications. The cost of these systems is however high due to the low conversion efficiencies possible from such sources (typically only 10% or less). Recently, interest in power recovery from such heat sources has increased, particularly for smaller units where the number of potential heat sources is greatest. The use of Rankine Cycles with organic working fluids (hydrocarbons or refrigerants) instead of steam is well established for low temperature power generation, and the expansion of liquid or 2-phase fluid (rather that superheated vapour) has been shown to improve performance. Depending on the application, waste heat recovery can be achieved using single cycles, or as cascaded systems where the heat from the source is used to heat fluid in a high temperature cycle, the condenser of which provides a heat input to a low temperature cycle which uses a different fluid. This project will investigate the effect that the choice of single or cascaded cycles has on the performance and the specification of components in the system for particular applications. A range of expander, pump and heat exchanger technologies will be considered in order to identify suitable system configurations to enable greater uptake of this technology.

Featured profile

Dr Sathiskumar Anusuya Ponnusami

People

Academic staff members

Research & Support Staff	PhD Researchers	Visiting academics
Dr Sham Rane Thibaud Plantegenet Aleksander Krupa Ivona Ivkovic-Kihic	Abhishek Kumar Neeraj Bikramaditya Halil Lacevic Shaikh Shahsharif Anurag Kishan	Dr Yan Di, Wuhan University of Science & Technology, China (Visiting Scholar)

Collaborators

Academic collaborators	Industrial partners
Professor Abdulnaser Sayma, Professor of Energy Engineering Professor Ranjan Banerjee, Professor of Structural Dynamics Professor Tong Sun, Professor of Sensor Engineering Professor Qinwei Ma, Professor of Hydrodynamics Dr Jafar Al Zaili, Research Fellow Professor Christoph Bruecker Dr Martin White Dr Sathiskumar Anusuya Ponnusami, Lecturer in Structural Mechanics (Aeronautics) Dr Shuaihui Sun, Xi’an University of Technology, China Professor Robert JK Wood, University of Southampton Dr Juan Guzman-Inigo, Lecturer in Aerospace Propulsion	Holroyd, Milnrow, Rochdale, United Kingdom Howden, Glasgow, United Kingdom Heliex Power, East Kilbride, United Kingdom Kirloskar, Pune, India Rotorcomp, Germering, Germany Jaecklin, Augsburg, Germany Comoti, Bucharest, Romania Mayekawa, Japan Megger, UK Chongqing Yuejin Machinery Co., Ltd Termommecanica Pompe, Italy VMC Italia, Creazzo, Italy Elgi Equipments, Coimbatore, India Vmac, Vacouver, Canada DV Systems, Barrie, Canada Ingersoll Rand-Trane, La Crosse, WI, USA Gardner Denver, Quincy, IL, USA Carrier Corporation, Syracuse, NY, USA Dalian Refrigeration, Dalian, China Wuxi Compressors, Wuxi, China JiuYi machinery Co. Ltd, HangZhou, China Edwards Pumps
Industrial collaborators
Dr. Billy Milligan, Howden, UK Donald Lawson, Howden, UK Dr. James Ure, Howden, UK Dr. Manoj Heiyantuduwa, Howden, UK Mr Neeraj Asati, Kirloskar, India Mr Neeraj Bhargava, Kirloskar, India

Past PhD students

Mohammad Arjeneh
David Buckney
Ms Ekaterina Chukanova
Georges Karagiorgios
Sasa Zagorac
Ahmed Kovacevic
Kupachi Venu Madhav
Elvedin Mujic
Diego Guerrato
Anegar Panesar
Chima Okezue
Sham Rane
Madhulika Kethidi
Evans Chikarakara
Syrifa Nur Aqida
Abdal Tamtam
Asnul Ahmed
Ahmet Aydin
Nausheen Basha
Suraj Abdan
Lu Yang
Brijeshkumar Patel
Sumit Patil
Thibault Tam

Alumni

Dr Apostolos Karvountzis
Amar Leto, University of Mostar, Bosnia (Research placement)
Lukas Richter, University of West Bohemia (Research Placement)
Jordan Christian, USA (Research Intern)
Dr Ermin Husak, University of Bihac, Bosnia and Herzegovina
Dr Elvedin Mujic - Research & Development, Bitzer, Germany
Dr Ashvin Dhunput
Dr Giuseppe Bianchi, Brunel University, UK
Dr Yan Di, State Key Laboratory of Mechanical Transmission, Chongqing University, China
Mr Sasa Milojevic, University of Stuttgart, Germany
I. McCimmie (Research Assistant)
K. VenuMadhav, Elgi India (Visiting Research Fellow)
Professor L Li, Xi’an Jiaotong University, China (Visiting Research Fellow)
Professor V. Supin, Xi’an Jiaotong University, China (Visiting Research Fellow)
Dr Xueyuan Peng, Xi’an Jiaotong University, China (Visiting Research Fellow)
Dr G. H. Lee, Doowon University, Korea (Visiting Research Fellow)
Mr W M Zhang, Dalian Refrigeration China (Visiting Research Fellow)
Mr J Liu, Dalian Refrigeration China (Visiting Research Fellow)
Mr J Z Chen, Dalian Refrigeration China (Visiting Research Fellow)
Mr J. M. Sun, Dalian Refrigeration China (Visiting Research Fellow)
Mr A. D. Carlsson, KTH, Sweden (Research Student)
Mr A Topcic (Research Engineer)
Mr Ming, JYC, China (Compressor Engineer)
Mr Xiajun Wu, Wuxi, China (Compressor Engineer)
Mr G Greenough, DVSystems, Canada (Compressor Engineer)
Dr Hyungki Shin, Senior Researcher, Korean Institute of Energy
Mr G Stupple, Jaecklin, Germany
Mr D Faksa, VSB – Technical University of Ostrava, Czech Republic
Mr Yan Di, State Key Laboratory of Mechanical Transmission, Chongqing University, China
Dr. Danqing Yin
Professor Fahmida Gulshan
Professor ASAW Kurney
Dr Kisorthman Vimalakanthan
Dr Gursharanjit Singh
Mohsen Ghavami
Jean-Pierre De Klerk

Facilities

Screw compressor laboratory

The Centre for Compressor Technology is equipped with one test rig able to test oil-injected and oil-free twin screw compressors up to 75 kW and 1000 m3/h (588 cfm) of delivered airflow. The test rig was built to meet CAGI and PNEUROP test standards and test procedure meet ISO 1217:2009 +A1:2016(E) standard (Displacements compressor – Acceptance tests).

The test rig is equipped with a 2 pole AC motor of 75 kW with maximum rotational speed of 3000 rpm and torque up to 250 Nm. The compressor is driven either directly by the motor, by belt pulley or by addition of an external gearbox.

Oil-injected screw compressors can be tested up to 12 bar (g) of discharge pressure and discharge temperature up to 100 ^oC. The test rig is equipped with an oil-cooler to cool oil at specified temperature. Air-oil mixture is separated at discharge using a two stages oil separator (centrifugal + filter).

Oil-free screw compressors can be tested up 2.8 bar (g) of discharge pressure and discharge temperature up to 200 ^oC.

Special capabilities/abilities on request:

4 pole AC motor of 75 kW and 500 Nm is available.
Test of other machines (scroll and vane compressor, roots blower, twin-screw expander…)
Testing with different oil

High-frequency data acquisition system (NI cRio) accompanied by LabView allows testing in steady-state or transient conditions, and for loaded or unloaded compressor, with real-time calculation of performances and monitoring of the compressor.

Measurements:

Pressure (suction and discharge).
Temperature (suction, discharge, oil injection).
Delivered airflow (Orifice plate – IS0 5167-2:2003 and PD ISO/TR 15377:2018).
Torque and rotational speed.
Oil flow rate.
Other capabilities: Dynamic pressure (Inside the compressor can allow plotting P-alpha diagram), Noise, Mechanical vibrations, Pressure at the oil-injection…

After testing extensive report is established presenting the test rig and compressor tested, tests conditions (pressure, temperatures) and measurements with usually performance maps of compressor plotted in function of speed or delivered flow and any additional required measurements.

Our new screw compressor test cell

Optical compressors laboratory

State of the art optical laboratory is specifically dedicated to study the flow field and Heat transfer phenomena in leakage flows as well as main flow in actual running condition of the positive displacement machines using high-end techniques such as Particle image velocimetry (PIV), High speed infrared thermography (IR) and Planar laser induced fluorescence (PLIF). This enables us to understand the flow physics inside the rotary machines. This facility can be leveraged to other applications such as turbines and aerodynamics.

Internal-Geared Machines laboratory

Currently, at City, a new test laboratory is being established to investigate a revolutionary new type of screw machine. An in-house designed testbed will allow testing of oil-injected IGSM with power up to 11kW. Internally-geared screw compressors have a number of potential advantages over conventional twin-screw configurations, including reduced leakage areas, co-directional thermal expansion, reduced rotor deflection, reduced viscous losses, and higher swept volume for a given machine envelope.

Refrigeration and ORC test laboratory for compressors, expanders and turbines

The expander test facility is a modified vapour-compression system with partial cooling/condensation using modern refrigerants. This test facility can replicate typical operating conditions within an ORC system, and will be used to conduct experiments on two-phase expansion using twin-screw expanders.

Publications

Publications by Centre for Compressor Technology

Patel, B., Kovacevic, A., Plantegenet, T. ORCID: 0000-0003-0585-3726 & Tam, T. (2023). Study of leakage flow in oil-free positive displacement rotary machines using particle image velocimetry. Experimental Thermal and Fluid Science, 145, 110886. doi: 10.1016/j.expthermflusci.2023.110886

Patel, H. H., Lakhera, V. J. & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2023). Validation of Leakage Model for an Oil-free Twin-Screw Compressor. Paper presented at the 48th National Conference on Fluid Mechanics and Fluid Power (FMFP), 27-29 Dec 2021, Pilani, India. doi: 10.1007/978-981-19-6970-6_49

Abdan, S., Patil, S., Stosic, N. ORCID: 0000-0001-8034-4046 , Kovacevic, A. ORCID: 0000-0002-8732-2242 & Smith, I. (2023). Experimental validation of the screw compressor oil drag model for various rotor profiles. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, doi: 10.1177/09544089231163514

Matuzović, M., Rane, S. ORCID: 0000-0002-8732-2242, Patel, B. , Kovacevic, A. & Tuković, Ž. (2022). Analysis of conjugate heat transfer in a roots blower and validation with infrared thermography. International Journal of Thermofluids, 16, 100234. doi: 10.1016/j.ijft.2022.100234

Plantegenet, T. ORCID: 0000-0003-0585-3726, Tam, T., Kovacevic, A. ORCID: 0000-0002-8732-2242 , Rane, S., Patel, B., Krupa, A., Leach, R. K., Lawson, D., Heiyantuduwa, M., Milligan, B. & Ure, J. (2022). Systematic engineering design approach for improvement of oil-free twin-screw compressors. IOP Conference Series: Materials Science and Engineering, 1267(1), 012002. doi: 10.1088/1757-899x/1267/1/012002

Abdan, S., Stosic, N. ORCID: 0000-0001-8034-4046, Kovacevic, A. ORCID: 0000-0002-8732-2242 , Smith, I. & Asati, N. (2022). Oil drag loss in oil-flooded, twin-screw compressors. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, doi: 10.1177/09544089221115493

Lu, Y., Rane, S. & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2022). Evaluation of cut cell cartesian method for simulation of a hook and claw type hydrogen pump. International Journal of Hydrogen Energy, 47(54), pp. 23006-23018. doi: 10.1016/j.ijhydene.2022.05.110

Ramchandran, G., Rane, S., Kovacevic, A. ORCID: 0000-0002-8732-2242 , Hoehn, C. & Sieder, S. (2022). Computational Modeling of Twin Screw Pumps for Thermal Management Applications. SAE International Journal of Passenger Vehicle Systems, 15(1), pp. 47-59. doi: 10.4271/15-15-01-0004

Sun, S., Wu, P., Guo, P. , Yi, G. & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2021). Numerical Investigation on a Twin-Screw Multiphase Pump Under low IGVF. International Journal of Fluid Machinery and Systems, 14(4), pp. 335-344. doi: 10.5293/IJFMS.2021.14.4.335

Patel, B., Kovacevic, A. ORCID: 0000-0002-8732-2242, Charogiannis, A. , Alam, M. N. & Schuette, M. (2021). The use of laser-induced fluorescence to measure temperature in the leakage gaps of oil-free positive displacement rotary machines. Measurement, 185, 110057. doi: 10.1016/j.measurement.2021.110057

Lu, Y., Kovacevic, A., Read, M. G. ORCID: 0000-0002-7753-2457 , Buckney, D. & Endo, Y. (2021). Investigation of Screw Compressors for Low Pressure Ratio Applications. IOP Conference Series: Materials Science and Engineering, 1180(1), ISSN 1757-8981 doi: 10.1088/1757-899x/1180/1/012006

Basha, N., Kovacevic, A. ORCID: 0000-0002-8732-2242 & Rane, S. (2021). Numerical investigation of oil injection in screw compressors. Applied Thermal Engineering, 193, 116959. doi: 10.1016/j.applthermaleng.2021.116959

Sun, S. H., Wu, P. B., Guo, P. C. , Yi, G. Z., Kovacevic, A. ORCID: 0000-0002-8732-2242, Zhang, H. & Wu, G. K. (2021). Numerical investigation on a double suction twin-screw multiphase pump. IOP Conference Series: Earth and Environmental Science, 774, ISSN 1755-1307 doi: 10.1088/1755-1315/774/1/012048

Patel, B., Kovacevic, A. ORCID: 0000-0002-8732-2242 & Krupa, A. (2021). On Measuring Velocity and Temperature in Leakage Flows of Oil Free Rotary Positive Displacement Machines. Paper presented at the International Conference “New Technologies, Development and Applications”, 24-26 Jun 2021, Sarajevo, Bosnia and Herzegovina. doi: 10.1007/978-3-030-75275-0_84

Rane, S., Kovacevic, A. ORCID: 0000-0002-8732-2242, Stosic, N. ORCID: 0000-0001-8034-4046 & Smith, I. (2021). Analysis of real gas equation of state for CFD modelling of twin screw expanders with R245fa, R290, R1336mzz(Z) and R1233zd(E). International Journal of Refrigeration, 121, pp. 313-326. doi: 10.1016/j.ijrefrig.2020.10.022

Rane, S. & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2021). 3D CFD modelling of twin screw expanders using real gas equation of state and refprop. 10th IIR conference on compressors and refrigerants, ISSN 0151-1637 doi: 10.18462/iir.compr.2021.0434

Kovacevic, A. ORCID: 0000-0002-8732-2242 & Rane, S. (2021). Challenges in 3D CFD Modelling of Rotary Positive Displacement Machines. Journal of Physics: Conference Series, 1909, 012063. doi: 10.1088/1742-6596/1909/1/012063

Vimalakanthan, K., Read, M. G. ORCID: 0000-0002-7753-2457 & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2020). Numerical Modelling and Experimental Validation of Twin-Screw Expander. Energies, 13(8), 4700. doi: 10.3390/en13184700

Vimalakanthan, K., Read, M. G. ORCID: 0000-0002-7753-2457 & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2020). Performance Prediction and Optimisation of Twin-Screw Expander. IIR Rankine Conference 2020, 1146. doi: 10.18462/iir.rankine.2020.146

Yan, D., Tang, Q., Kovacevic, A. ORCID: 0000-0002-8732-2242 , Zhang, Y., Liu, W., Liang, P. & Zhang, H. (2020). Designing nano-aluminum laden fuel pump for aviation applications. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 234(6), pp. 634-643. doi: 10.1177/0954408920935315

Sun, S., Singh, G., Kovacevic, A. ORCID: 0000-0002-8732-2242 & Bruecker, C. ORCID: 0000-0001-5834-3020 (2020). Experimental and numerical investigation of tip leakage flows in a roots blower. Designs, 4(1), 3. doi: 10.3390/designs4010003

Basha, N., Kovacevic, A. ORCID: 0000-0002-8732-2242 & Rane, S (2019). Analysis of oil-injected twin-screw compressor with multiphase flow models. Designs, 3(4), 54. doi: 10.3390/designs3040054

Singh, G. ORCID: 0000-0001-7456-7868, Sun, S., Kovacevic, A. , Li, Q. & Bruecker, C. (2019). Transient flow analysis in a Roots blower: Experimental and numerical investigations. Mechanical Systems and Signal Processing, 134, 106305. doi: 10.1016/j.ymssp.2019.106305

Abdan, S., Basha, N., Kovacevic, A. ORCID: 0000-0002-8732-2242 , Stosic, N., Birari, A. & Asati, N. (2019). Development and Design of Energy Efficient Oil-Flooded Screw Compressors. IOP Conference Series: Materials Science and Engineering, 604(1), ISSN 1757-8981 doi: 10.1088/1757-899X/604/1/012015

Abdan, S., Stosic, N., Kovacevic, A. ORCID: 0000-0002-8732-2242 , Smith, I. K. ORCID: 0000-0003-1524-9880 & Asati, N. (2019). Analysis of rolling bearing power loss models for twin screw oil injected compressor. IOP Conference Series: Materials Science and Engineering, 604(1), ISSN 1757-8981 doi: 10.1088/1757-899X/604/1/012013

Basha, N., Kovacevic, A. ORCID: 0000-0002-8732-2242 & Rane, S. (2019). User defined nodal displacement of numerical mesh for analysis of screw machines in FLUENT. IOP Conference Series: Materials Science and Engineering, 604(1), doi: 10.1088/1757-899X/604/1/012012

Casari, N., Fadiga, E., Pinelli, M. , Suman, A., Kovacevic, A. ORCID: 0000-0002-8732-2242, Rane, S. & Ziviani, D. (2019). Numerical investigation of oil injection in a Roots blower operated as expander. IOP Conference Series: Materials Science and Engineering, 604(1), 12075. doi: 10.1088/1757-899X/604/1/012075

Husak, E., Kovacevic, A. ORCID: 0000-0002-8732-2242 & Karabegovic, I. (2019). Calculation of clearances in twin screw compressors. IOP Conference Series: Materials Science and Engineering, 604(1), ISSN 1757-8981 doi: 10.1088/1757-899X/604/1/012001

Stosic, N., Smith, I. K. & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2019). Improving Screw Compressor Displacement and Efficiency by Increasing the Rotor Profile Depth. IOP Conference Series: Materials Science and Engineering, 604(1), ISSN 1757-8981 doi: 10.1088/1757-899X/604/1/011012

Yang, L., Kovacevic, A. ORCID: 0000-0002-8732-2242 & Read, M. (2019). Normal Rack Grid Generation Method for Screw Machines with Large Helix Angles. IOP Conference Series: Materials Science and Engineering, 604(1), ISSN 1757-8981 doi: 10.1088/1757-899X/604/1/012011

Bianchi, G., Rane, S., Fatigati, F. , Cipollone, R. & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2019). Numerical CFD simulations and indicated pressure measurements on a sliding vane expander for heat to power conversion applications. Designs, 3(3), 31. doi: 10.3390/designs3030031

Lu, Y., Kovacevic, A. ORCID: 0000-0002-8732-2242, Read, M. G. ORCID: 0000-0002-7753-2457 & Basha, N (2019). Numerical study of customised mesh for twin screw vacuum pumps. Designs, 3(4), 52. doi: 10.3390/designs3040052

Abdan, S., Stosic, N., Kovacevic, A. ORCID: 0000-0002-8732-2242 , Smith, I. K. & Deore, P. (2018). Identification and analysis of screw compressor mechanical losses. IOP Conference Series: Materials Science and Engineering, 425(1), 12015. doi: 10.1088/1757-899X/425/1/012015

Basha, N., Kovacevic, A. ORCID: 0000-0002-8732-2242, Stosic, N. & Smith, I. K. (2018). Effect of oil-injection on twin screw compressor performance. IOP Conference Series: Materials Science and Engineering, 425(1), 12009. doi: 10.1088/1757-899X/425/1/012009

Casari, N., Pinelli, M., Suman, A. , Kovacevic, A. ORCID: 0000-0002-8732-2242, Rane, S. & Ziviani, D. (2018). Full 3D numerical analysis of a twin screw compressor by employing open-source software. IOP Conference Series: Materials Science and Engineering, 425(1), 12017. doi: 10.1088/1757-899X/425/1/012017

Lu, Y., Kovacevic, A. ORCID: 0000-0002-8732-2242 & Read, M. G. ORCID: 0000-0002-7753-2457 (2018). Numerical study on screw machines with large helix angles. IOP Conference Series: Materials Science and Engineering, 425(1), 12015. doi: 10.1088/1757-899X/425/1/012023

Sun, S. H., Kovacevic, A., Bruecker, C. , Leto, A., Singh, G. & Ghavami, M. (2018). Numerical and Experimental Analysis of Transient Flow in Roots Blower. IOP Conference Series: Materials Science and Engineering, 425, 12024. doi: 10.1088/1757-899X/425/1/012024

Sun, S., Kovacevic, A. ORCID: 0000-0002-8732-2242, Bruecker, C. ORCID: 0000-0001-5834-3020 , Ghavami, M., Rane, S., Singh, G. & Leto, A. (2018). Experimental Investigation of the Transient Flow in Roots Blower. Paper presented at the 24th International Compressor Engineering Conference, 9 - 12 July 2018, Purdue University, West Lafayette, USA.

Yan, D., Kovacevic, A. ORCID: 0000-0002-8732-2242 & Tang, Q. (2017). Numerical investigation of cavitation in twin-screw pumps. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, doi: 10.1177/0954406217740927

Bianchi, G., Kovacevic, A., Cipollone, R. , Murgia, S. & Contaldi, G. (2017). Numerical CFD simulations on a small-scale ORC expander using a customized grid generation methodology. Energy Procedia, 129, pp. 843-850. doi: 10.1016/j.egypro.2017.09.199

Bianchi, G., Kovacevic, A., Cipollone, R. , Murgia, S. & Contaldi, G. (2017). Grid generation methodology and CFD simulations in sliding vane compressors and expanders. IOP Conference Series: Materials Science and Engineering, 232(012053), doi: 10.1088/1757-899X/232/1/012053

Kovacevic, A. (2017). Application of numerical grid generation for improved CFD analysis of multiphase screw machines. IOP Conference Series: Materials Science and Engineering, 232(012017), doi: 10.1088/1757-899X/232/1/012017

Kovacevic, A. ORCID: 0000-0002-8732-2242 (2017). Foreword. IOP Conference Series: Materials Science and Engineering, 232(1), 11001. doi: 10.1088/1757-899X/232/1/011001

Yan, D., Kovacevic, A. & Tang, Q. (2017). Numerical investigation of flow characteristics in twin-screw pump under cavitating conditions. IOP Conference Series: Materials Science and Engineering, 232(012026), doi: 10.1088/1757-899X/232/1/012026

Kovacevic, A. ORCID: 0000-0002-8732-2242, Vukasinovic, N., Pavkovic, N. & Horak, P. (2017). Evaluation of “Codeve” methodology for teaching npd to virtual design teams. In: Proceedings of the 19th International Conference on Engineering and Product Design Education (E&PDE17), Building Community: Design Education for a Sustainable Future. (pp. 555-560). Glasgow: The Design Society.

Kovacevic, A. (2017). Modeling of Multiphase Twin Screw Machines. Keynote Paper presented at the 8th International Conference on Compressors and Refrigeration, 20-22 Jul 2017, Xi'an, China.

Kovacevic, A. (2017). Algebraic generation of single domain computational grid for twin screw machines. Part I. Implementation. Advances in Engineering Software, 107, pp. 38-50. doi: 10.1016/j.advengsoft.2017.02.003

Yan, D., Tang, Q., Kovacevic, A. & Pei, L. (2017). Rotor profile design and numerical analysis of 2–3 type multiphase twin-screw pumps. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, doi: 10.1177/0954408917691798

Kovacevic, A., Stosic, N. & Smith, I. K. (2017). Editorial. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 231(1), p. 3. doi: 10.1177/0954408916685022

Bianchi, G., Kovacevic, A. & Cipollone, R. (2017). Deforming grid generation for numerical simulations of fluid dynamics in sliding vane rotary machines. Advances in Engineering Software, 112, pp. 180-191. doi: 10.1016/j.advengsoft.2017.05.010

Kovacevic, A. (2017). Algebraic generation of single domain computational grid for twin screw machines. Part II. Validation. Advances in Engineering Software, 109, pp. 31-43. doi: 10.1016/j.advengsoft.2017.03.001

Yan, D., Kovacevic, A., Tang, Q. & Zhang, W. H. (2016). Numerical modelling of twin-screw pumps based on computational fluid dynamics. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, doi: 10.1177/0954406216670684

Mujic, E., Stosic, N., Kovacevic, A. & Smith, I. K. (2016). Noise Control by Suppression of Gas Pulsation in Screw Compressors. In: Ahmed, N. (Ed.), Advances in Noise Analysis, Mitigation and Control. . InTech. doi: 10.5772/64795

Vidovics, B., Vukasinovic, N., Pavkovic, N. & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2016). Development of methodology for distributed collaborative design environment. In: Proceedings of the 18th International Conference on Engineering and Product Design Education (E&PDE16), Design Education: Collaboration and Cross-Disciplinarity. (pp. 58-63). Glasgow: The Design Society. ISBN 9781904670780

Read, M. G., Smith, I. K., Stosic, N. & Kovacevic, A. (2016). Comparison of organic rankine cycle systems under varying conditions using turbine and twin-screw expanders. Energies, 9(8), 614. doi: 10.3390/en9080614

Bianchi, G., Kovacevic, A., Cipollone, R. , Murgia, S. & Contaldi, G. (2016). Development of a general numerical methodology for CFD analyses in sliding vane machines and application on a mid-size oil injected air compressor. Paper presented at the 23rd International Compressor Engineering Conference, 11-14 Jul 2016, Indiana, USA.

Kovacevic, A. & Stosic, N. (2016). CFD Analysis of Oil Flooded Twin Screw Compressors. Paper presented at the 23rd International Compressor Engineering Conference, 11-14 Jul 2016, Indiana, USA.

Chukanova, E., Stosic, N. & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2016). Modelling and Experimental Investigation of Compressor Plant Operation Under Unsteady Conditions. In: ASME 2015 International Mechanical Engineering Congress and Exposition, Volume 4A: Dynamics, Vibration, and Control. . ASME. ISBN 978-0-7918-5739-7

Buckney, D., Kovacevic, A. & Stosic, N. (2016). Design and evaluation of rotor clearances for oil-injected screw compressors. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 231(1), pp. 26-37. doi: 10.1177/0954408916660342

Stosic, N., Rane, S., Kovacevic, A. ORCID: 0000-0002-8732-2242 & Smith, I. K. ORCID: 0000-0003-1524-9880 (2016). Screw Rotor Profiles of Variable Lead Vacuum and Multiphase Machines and Their Calculation Models. In: ASME 2016 International Mechanical Engineering Congress and Exposition, Volume 6A: Energy. . ASME. ISBN 978-0-7918-5058-9 doi: 10.1115/IMECE2016-66314

Mamo, J., Farrugia, P., Borg, J. , Wodehouse, A., Grierson, H. & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2015). Using engineering design tools in multidisciplinary distributed student teams. In: Kovacevic, A. ORCID: 0000-0002-8732-2242, Bingham, G. & Parkinson, B. (Eds.), Proceedings of the 17th International Conference on Engineering and Product Design Education (E&PDE15), Great Expectations: Design Teaching, Research & Enterprise. (pp. 99-104). Glasgow: The Design Society. ISBN 9781904670629

Kovacevic, A. (2015). 9th International Conference on Compressors and their Systems. IOP Conference Series: Materials Science and Engineering, 90(011001), doi: 10.1088/1757-899X/90/1/011001

Schembri, M., Farrugia, P., Wodehouse, A. J. , Grierson, H. & Kovacevic, A. (2015). Influence of sketch types on distributed design team work. CoDesign, 11(2), pp. 99-118. doi: 10.1080/15710882.2015.1054841

Arjeneh, M., Kovacevic, A., Manolis, M. & Stosic, N. (2015). Numerical and Experimental Investigation of Pressure Losses at Suction of a Twin Screw Compressor. IOP Conference Series: Materials Science and Engineering, 90(1), 12006. doi: 10.1088/1757-899X/90/1/012006

Buckney, D., Kovacevic, A. & Stosic, N. (2015). Rotor clearance design and evaluation for an oil injected twin screw compressor. IOP Conference Series: Materials Science and Engineering, 90(1), 12003. doi: 10.1088/1757-899X/90/1/012003

Kovacevic, A. & Stosic, N. (2015). Analytical Grid Generation for accurate representation of clearances in CFD for Screw Machines. IOP Conference Series: Materials Science and Engineering, 90(1), 12008. doi: 10.1088/1757-899X/90/1/012008

Madhav, K. V. & Kovacevic, A. (2015). Economics of water injected air screw compressor systems. IOP Conference Series: Materials Science and Engineering, 90(1), 12012. doi: 10.1088/1757-899X/90/1/012012

Kovacevic, A. & Udo, N. (2014). Fluid Machine - Bearing Inserts. Kovacevic,A., Udo, N. patent no. US 2014/0322059 A1

Kovacevic, A., Stosic, N. & Kethidi, M. (2014). Deforming grid generation and CFD analysis of variable geometry screw compressors. Computers & Fluids, 99, pp. 124-141. doi: 10.1016/j.compfluid.2014.04.024

Arjeneh, M., Kovacevic, A. ORCID: 0000-0002-8732-2242, Stosic, N. & Gavaises, M. ORCID: 0000-0003-0874-8534 (2014). Study of Multiphase Flow at the Suction of Screw Compressor. Paper presented at the 22nd International Compressor Engineering Conference at Purdue 2014, 14 - 17 July 2014, West Lafayette, Indiana.

Kovacevic, A., Stosic, N., Jiang, Y. , Furmanczyk, M. & Lowry, S. (2014). Influence of approaches in CFD Solvers on Performance Prediction in Screw Compressors. Paper presented at the 22nd International Compressor Engineering Conference, 14-17 Jul 2014, West Lafayette, USA.

Rane, S., Kovacevic, A., Stosic, N. & Kethidi, M. (2013). Grid deformation strategies for CFD analysis of screw compressors. International Journal of Refrigeration, 36(7), pp. 1883-1893. doi: 10.1016/j.ijrefrig.2013.04.008

Stosic, N., Smith, I. K., Chukanova, E. & Kovacevic, A. (2013). Experimental Investigation and Numerical Modelling of Dynamic Behaviour of Screw Compressor Plant. Universal Journal of Engineering Science, 1, pp. 68-79. doi: 10.13189/ujes.2013.010302

Buckney, D., Kovacevic, A. & Stosic, N. (2013). Experimental validation of a geometry model for twin screw machines. In: 8th International Conference on Compressors and their Systems. (pp. 237-246). Cambridge: Woodhead Publishing.

Chukanova, E., Stosic, N. & Kovacevic, A. (2013). Numerical analysis of unsteady behaviour of a screw compressor plant system. In: 8th International Conference on Compressors and their Systems. (pp. 129-139). Cambridge: Woodhead Publishing.

Kovacevic, A. & Rane, S. (2013). 3D CFD analysis of a twin screw expander. In: 8th International Conference on Compressors and their Systems. (pp. 417-429). Cambridge: Woodhead Publishing.

Kovacevic, A. & Stosic, N. (2013). Grid Generation for Screw Compressors with Variable Geometry Rotors. International Journal of Aerospace and Lightweight Structures, 3(2), doi: 10.3850/S2010428613000603

Pascu, M., Heiyanthuduwage, M. A., Mounoury, S. , Cooke, G.M.E. & Kovacevic, A. (2013). A study on the influence of the suction arrangement on the performance of twin screw compressors. In: ASME 2013 International Mechanical Engineering Congress and Exposition. Fluids Engineering Systems and Technologies, 7 A. . American Society of Mechanical Engineers (ASME). doi: 10.1115/IMECE2013-62391

Rane, S., Kovacevic, A., Stosic, N. & Kethidi, M. (2013). CFD grid generation and analysis of screw compressor with variable geometry rotors. In: 8th International Conference on Compressors and their Systems. (pp. 601-612). Cambridge: Woodhead Publishing.

Kovacevic, A. & Kethidi, M. (2012). CFD Modeling in Screw Compressors with complex multi rotor configurations. Paper presented at the 21st International Compressor Engineering Conference, 16-19 Jul 2012, Indiana, USA.

Stosic, N., Smith, I. K. ORCID: 0000-0003-1524-9880 & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2012). Numerical and experimental research in heat transfer to screw compressor rotors. Frontiers in Heat and Mass Transfer, 3(2), 23003. doi: 10.5098/hmt.v3.2.3003

Heiyanthuduwage, M. A., Mounoury, S. & Kovacevic, A. (2011). Performance prediction methods for screw compressors. In: 7th International Conference on Compressors and their Systems 2011. (pp. 411-420). Woodhead Publishing Limited.

Kovacevic, A., Mujic, E., Stosic, N. & Smith, I. K. (2011). Extending the Role of Computational Fluid Dynamics in Screw Machines. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 225(2), pp. 83-97. doi: 10.1177/0954408910397586

Mujic, E., Kovacevic, A., Stosic, N. & Smith, I. K. (2011). Noise generation and suppression in twin screw compressors. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 225(2), pp. 127-148. doi: 10.1177/1464419311403875

Smith, I. K., Stosic, N., Mujic, E. & Kovacevic, A. (2011). Steam as the working fluid for power recovery from exhaust gases by means of screw expanders. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 225(2), pp. 117-125. doi: 10.1177/2041300910393429

Stosic, N., Smith, I., Kovacevic, A. & Mujic, E. (2011). Review of Mathematical Models in Performance Calculation of Screw Compressors. International Journal of Fluid Machinery and Systems, 4(2), pp. 271-288. doi: 10.5293/IJFMS.2011.4.2.271

Stosic, N., Smith, I. K. ORCID: 0000-0003-1524-9880, Kovacevic, A. ORCID: 0000-0002-8732-2242 & Mujic, E. (2011). Geometry of screw compressor rotors and their tools. Journal of Zhejiang University-SCIENCE A, 12(4), pp. 310-326. doi: 10.1631/jzus.A1000393

Stosic, N., Smith, I. K. & Kovacevic, A. (2009). Steam as the Working Fluid for Power Recovery from Exhaust Gases by Means of Screw Expanders. Paper presented at the International Conference on Compressors and Their Systems, 07-09-2009 - 09-09-2009, London, England.

Mujic, E., Kovacevic, A., Stosic, N. & Smith, I. K. (2008). The influence of port shape on gas pulsations in a screw compressor discharge chamber. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 222(4), pp. 211-223. doi: 10.1243/09544089JPME205

Kovacevic, A. (2008). Competence development in an international product design course. In: Proceedings DESIGN 2008, the 10th International Design Conference. (pp. 1383-1392). The Design Society.

Kovacevic, A. ORCID: 0000-0002-8732-2242, Stosic, N., Mujic, E. & Smith, I. K. ORCID: 0000-0003-1524-9880 (2007). CFD Integrated Design of Screw Compressors. Engineering Applications of Computational Fluid Mechanics, 1(2), pp. 96-108. doi: 10.1080/19942060.2007.11015185

Kovacevic, A. ORCID: 0000-0002-8732-2242 (2005). Boundary adaptation in grid generation for CFD analysis of screw compressors. International Journal for Numerical Methods in Engineering, 64(3), pp. 401-426. doi: 10.1002/nme.1376

Kovacevic, A. ORCID: 0000-0002-8732-2242, Stosic, N. & Smith, I. K. ORCID: 0000-0003-1524-9880 (2004). A numerical study of fluid-solid interaction in screw compressors. International Journal on Computer Application in Technology, 21(4), pp. 148-158. doi: 10.1504/IJCAT.2004.006651

Stosic, N., Smith, I. K. ORCID: 0000-0003-1524-9880 & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2003). Optimisation of screw compressors. Applied Thermal Engineering, 23(10), pp. 1177-1195. doi: 10.1016/S1359-4311(03)00059-0

Stosic, N., Smith, I. K. ORCID: 0000-0003-1524-9880 & Kovacevic, A. ORCID: 0000-0002-8732-2242 (2003). Rotor interference as a criterion for screw compressor design. Journal of Engineering Design, 14(2), pp. 209-220. doi: 10.1080/0954482031000091518

Stosic, N., Kovacevic, A. ORCID: 0000-0002-8732-2242 & Smith, I. K. ORCID: 0000-0003-1524-9880 (2003). Three Dimensional Numerical Analysis of Screw Compressor Performance. Journal of Computer Methods in Applied Mechanics and Engineering, 3(2), pp. 259-284. doi: 10.3233/JCM-2003-3206

Kovacevic, A. (2002). Three dimensional numerical analysis for flow prediction in positive displacement screw machines. (Unpublished Doctoral thesis, City University London)

Professor Ahmed Kovacevic Howden/RAEng Chair in Compressor Technology e: [email protected] t: +44 (0)20 7040 8780
London EC1V 0HB United Kingdom