![[Dept of Engineering]](http://www.eng.cam.ac.uk/images/house_style/engban-s.gif){kind=small}
Compressor Dynamics
Intermediate Pressure Turbine Aerodynamics
Turbine Shroud Leakage Flows
Unsteady Transition in LP Turbines
Unsteady Flow in High Pressure Steam Turbines
Turbine Cooling
Compact Heat Exchangers
Instrumentation
High Pressure Steam Turbines
CFD Development
Aerodynamic Optimisation
Transonic Fan Design
Combustion Instability
Water Ingestion
Nacelle-Cross Wind Interaction
Helicopter Noise
Compressor Leakage Flows
Calculating Compression System Stability
Professor J.D. Denton
Dr T.P. Hynes
Various aspects of compressor aerodynamics are being investigated. A study of separations and singular behaviour in compressor passages is in progress, this arose out of previous work to design three-dimensional compressor blades which showed that the usual (two-dimensional) description of separation is inadequate in three dimensions. Another three-dimensional flow being investigated is the behaviour and design of bleed slots. These are to remove air from the compressor to cool hot components, improve handling or pressurise the aircraft. It has been found that the inclusion of a honeycomb at the slot entrance produces significant increases in pressure recovery.
Professor J.D. Denton
Mr E.M. Curtis
The model IP turbine rig is being used to study a new type of shed vortex that appears in the current design of the rig but which has not previously been observed on any other turbine. Similar vortices have now been predicted in real machines. The design of new blading, which is aimed to have the benefits of more uniform flow but without the vortex, has been completed and testing will commence very shortly. A development of the design process is that the new design has been produced by automated running of the 3D CFD codes. The design of a new build of the rig to model the flow in the IP turbines of future large civil aero engines has been completed and its manufacture commenced. This will be tested in the coming year.
Professor J.D. Denton
Dr J.P. Longley
An investigation of the flow over the tips of shrouded turbine blades has commenced. This flow is known to induce additional losses in downstream blade rows in addition to the direct loss of the leakage flow itself. A large scale low speed cascade model of the flow has been constructed and testing is about to start. Flow visualisation studies in a water tunnel are also planned as is CFD modelling of this complex flow.
Dr H.P. Hodson
Professor W.N. Dawes
Dr A.M. Savill
Dr R.J. Howell
The long-term research programme into Low Pressure Turbines for aero-engines has already resulted in new "high-lift" turbine designs that have entered service with the Rolls-Royce BR-715 engine on the Boeing 717 aircraft. These turbines have a 20 percent fewer airfoils compared to previous generations, thus saving a considerable amount of weight and cost. The same technology is now being incorporated into the new Rolls-Royce Trent 900 for the Airbus A380. A new "Ultra-high-lift" Low Pressure Turbine based on more recent research was successfully tested in February 2000 by Rolls-Royce Deutschland. This turbine had a similar further reduction in the number of airfoils. Current LP turbine research, which is aimed at reducing the number of stages in the low-pressure turbine, is sponsored by ITP of Spain. Collaborations with several institutions, notably the Universities of Leicester and Manchester, are concerned with improving our understanding of the fundamental reasons for the success of this research. This work is funded by the EPSRC. An investigation of the potential application of the same technology in compressors is being sponsored by Rolls-Royce.
Dr H.P. Hodson
In the many high pressure turbines, the effects of bladerow interaction are not usually beneficial. Research aimed at improving the understanding of the flow through high pressure steam turbines is being conducted with the sponsorship of Mitsubishi Heavy Industries of Japan. To date, the work has been aimed at understanding the unsteady processes responsible for the generation of inefficiency. Computational studies complement the experimental work that is being conducted in the large scale axial flow turbine rig. Future work is aimed at improving the heat transfer characteristics and, therefore, the life of high pressure turbines by taking account of these phenomena.
Dr H.P. Hodson
Professor W.N. Dawes
Dr. A.M. Savill
The rate of heat transfer to and from aircraft engine components often limits the life and performance of the engine. Even though this rate is usually dictated by aerodynamic phenomena, this is not often recognised in the research community. Two research grants, one funded by the EPSRC and one by the EC, have begun to address some of these issues. This work builds on previous combined theoretical-experimental studies of the aerodynamic penalties of film cooling.
Dr H.P. Hodson
Dr. T.J. Lu
Professor M.F. Ashby
Professor W.N. Dawes
Lattice-frame structured materials are a new development made possible by computer based design and control of numerically controlled processing. They consist of a 3-D network of struts or plates. The important feature is scale: the cells of the structure are a few mm in size. Current research is aimed at the utilisation of lattice-frame structured materials as compact and highly efficient heat dissipation media with high stiffness and strength. The heat-transfer and fluid-flow characteristics of metal lattice-frame materials are being investigated with the sponsorship of the EPSRC.
Dr H.P. Hodson
Dr H. Babinsky
Professor W.N. Dawes
Dr C. Durkan
Dr D.F. Moore
Professor M.E. Welland
A new multi-disciplinary departure, the application of Micro Electronic and Mechanical Systems (MEMS) to aircraft engines and other areas, has also begun. As well as aiding fundamental research, this is an important step toward the creation of "smart" aero-engines. The first steps of this programme are now complete and a number of aerodynamic sensors have been designed. The first research grant was awarded during 2000 by the EPSRC. In addition, the transonic probe calibration facility continues to be used for the investigation and calibration of miniature probes that are often used in high-speed research rigs.
Professor J.D. Denton
A new set of low reaction blading has been tested in the model HP steam turbine. This provided a datum for a new three-dimensional design, which is now being tested. Initial results show a significant improvement in performance for the new design but the increase in efficiency is not as great as that previously obtained for 50% reaction turbines. The detailed flow in the new design is now being measured with particular emphasis on understanding the unsteady flow.
Professor J.D. Denton
Dr L. Xu
CFD codes developed over many years continue to undergo improvements. These codes are in widespread use in industry. A new development this year has been the addition of a "dual timestepping" algorithm to the 3D unsteady code UNSTREST. This enables unsteady solutions with fine grids to be obtained much more efficiently than the previous explicit timestepping. The unsteady program has also been developed to include the option of simulated, rather than calculated, viscous effects. This enables realistic solutions to be obtained using much coarser grids than are necessary for full viscous calculations, thereby saving orders of magnitude of computing time and making full-annulus unsteady calculation practicable for the first time. A completely new multiblock code aimed at calculating the flow in complex geometries has been written over the past year. This is now working and is being applied to the flow over turbine tip seals, considerable development of it is foreseen over the coming year.
Professor W.N. Dawes
Methods of coupling CFD solvers with geometric parameterisation and optimisation software are being developed. The aims are to reduce design times and cost and to enable innovative designs to be explored. When developed, this tool will be used to produce an optimised design of the Deverson compressor.
Professor J.D. Denton
Dr L. Xu
Two new transonic fan designs aimed at low noise have been produced as part of the EU RESOUND project. These have been tested by Rolls-Royce with measurements of both noise and overall performance. Significant reductions in fan tone nose were obtained. Studies of the three-dimensional design of fan blading continue with the objective of understanding why some 3D fans perform better than conventional ones but some do not.
Dr I.J. Day
Combustion instabilities are an undesirable side effect of the lean pre-mixed fuelling technique used to reduce NOx emissions in modern gas turbines. Damaging pressure fluctuations build up due to the interaction of acoustic waves in the combustion chamber with the fuel mixing process. Methods of damping the acoustic waves and improving the fuel mixing process are both being studied. Perforated liners and Helmholtz resonators have been designed and tested for acoustic absorption in the non-linear range, i.e. where the pressure fluctuations are very large. The fuel pre-mixing process is being investigated with the aim of finding mixing systems which are insensitive to downstream pressure fluctuations. One such system has been patented and is giving good results in preliminary hot testing. This work is being applied by Rolls-Royce to Aeroderivative gas turbines on a very short time scale.
Professor J.B. Young
Dr I.J. Day
Water ingestion by an engine flying into heavy rain is being studied using a combination of experimental work and CFD. Water in the compressor is known to affect both the aerodynamic and the thermodynamic behaviour of the engine. Experiments using a low speed compressor are in progress to find out how water droplets behave as they enter the compressor, and to study the subsequent deposition, centrifuging and splashing which will occur in each of the blade row. The theoretical work uses a combination of CFD and mechanical analysis to predict droplet deposition and then to model the subsequent movement of the accumulated water. So far high deposition rates have been predicted for the first rotor, and have been confirmed by the experiments.
Dr T.P. Hynes
The tendency of intakes to separate in an unsteady manner under light cross winds is poorly understood. An experimental program, using a model fan and nacelle in a wind tunnel has shown that the separation and reattachment show hysteresis with change of wind direction. This has provided the first clear indications of the parameters which influence this phenomenon. A semi-analytical model has been developed which enables the unsteady separation characteristics of a nacelle to be inferred from steady state tests.
Dr T.P. Hynes
The biggest challenge facing high-speed helicopter operation is the need to reduce the noise associated with the unsteady shock motion on the rotors. This is being investigated computationally. An unsteady shock-capturing method is under development which uses a much tighter spatial stencil to enable accurate shock predictions on relatively coarse grids.
Dr J.P. Longley
The mechanical construction of aeroengine compressors allows very small leakage flows, of the order of 0.5% of the total mass flow rate, beneath the stator shroud. Research into the interaction between stator-shroud seal leakage flow and the mainstream aerodynamics has yielded surprising results. Depending upon the tangential momentum of the leakage flow the aerodynamics of the stator blade row can be substantially degraded or slightly improved. The research has been jointly funded by EPSRC and Rolls-Royce.
Dr J.P. Longley
Development continues on a time-accurate simulation of the flow within aeroengine compression systems. The simulation is well able to reproduce observed trends in compression system instability. A Rolls-Royce funded project has now started to apply the simulation to their compressor designs.
C1. Babinsky, H., Kuschel, U., Hodson, H.P., Moore, D.F., Welland, M.E. The aerodynamic design and use of multi-sensor pressure probes for MEMS applications. Measuring Techniques in Turbomachinery, Proceedings, 15th Symposium on Measuring Techniques for Transonic and Supersonic Flows in Cascades and Turbomachines, Florence, Italy (September 2000); Edited by G. Manfrida, D. Contini (Universita degli di Firenze, 2000). Paper and CD.
C2. Dambach, R., Hodson, H.P., Huntsman. I. An experimental study of tip clearance flow in a radial inflow turbine. Transactions of the ASME, Journal of Turbomachinery, 121, (4), 644-650 (October 1999).
C3. Demargne, A.A.J., Longley, J.P. The aerodynamic interaction of stator shroud leakage and mainstream flows in compressors. ASME Turbo Expo 2000, 45th ASME International Gas Turbine and Aeroengine Technical Congress, Exposition and Users Symposium, Munich, Germany, ASME paper 2000-GT-0570 (May 2000).
C4. Denton, J.D. State of the art and future of turbine technology. Proceedings, International Gas Turbine Congress, Kobe, Japan; Edited by T. Tamaru, 27-37 (November 1999).
C5. Denton, J.D. (Editor) Developments in Turbomachinery Design. (Professional Engineering Publishing, 1999). ISBN 1-86058-2370
C6. Friedrichs, S., Hodson, H.P., Dawes, W.N. The design of an improved endwall film-cooling configuration. Transactions of the ASME, Journal of Turbomachinery, 121, (4), 772-780 (October 1999).
C7. Gjerstad, S., Fu, Y., Hodson, H.P., Dawes, W.N., Moore, D.F. A study of the frequency response of a micro machined shear stress sensor based on thin film anemometry. Measuring Techniques in Turbomachinery, Proceedings, 15th Symposium on Measuring Techniques for Transonic and Supersonic Flows in Cascades and Turbomachines, Florence, Italy (September 2000); Edited by G. Manfrida, D. Contini (Università degli di Firenze, 2000). Paper and CD.
C8. Goloviznin, V.M., Hynes, T.P., Karabasov, S.A. Comparative analysis of several high-resolution TVD schemes for the one dimensional Euler equations. 3rd International Conference on Finite Difference Schemes, Palanga, Lithuania (September 2000).
C9. Harvey, N.W., Schulte, V., Howell, R.J., Hodson, H.P. The role of research in the aerodynamic design of an advanced low pressure turbine. Proceedings of the Institution of Mechanical Engineers Part A, Journal of Power and Energy, 213, (A4), 235-242 (1999).
C10. Hill, P.G., Miyagawa, K., Denton, J.D. Fast and accurate inclusion of steam properties in two and three-dimensional steam turbine flow calculations. Proceedings of Institution of Mechanical Engineers Part C, Journal of Mechanical Engineering Science, 214, (C7), 903-919 (2000).
C11. Hodson, H.P., Howell, R.J. High lift low pressure turbines. Minnowbrook III: Boundary Layer Transition and Unsteady Aspects of Turbomachinery Flows, Minnowbrook, Syracuse, New York, USA (August 2000).
C12. Hodson, H.P., Howell, R.J. Unsteady flow: its role in the low pressure turbine. 9th International Symposium on Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines, Lyon, France (September 2000).
C13. Howell, R.J., Hodson, H.P. Separation bubble interactions with turbulent spots and wakes in the turbomachinery environment at a Reynolds of around 130,000. Minowbrook III: Boundary Layer Transition and Unsteady Aspects of Turbomachinery Flows, Minnowbrook, Syracuse, New York, USA (August 2000).
C14. Howell, R.J., Ramesh, O.N., Hodson, H.P., Harvey, N.W., Schulte, V. High lift and aft loaded profiles for low pressure turbines. ASME Turbo Expo 2000, 45th ASME International Gas Turbine and Aeroengine Technical Congress, Exposition and Users Symposium, Munich, Germany, ASME paper 2000-GT-0261 (May 2000). Published in: Transactions of the ASME, Journal of Turbomachinery, 123, (2), 181-188 (April 2001).
C15. Kittichaikarn, C., Ireland, P.T., Zhong, S., Hodson, H.P. The visualisation and measurement of the onset, turbulent spot production rate, intermittency and heat transfer during wake-induced transition using thermochromic liquid crystals. Minnowbrook III: Boundary Layer Transition and Unsteady Aspects of Turbomachinery Flows, Minnowbrook, Syracuse, New York, USA (August 2000).
C16. Marshall, J.G., CHEW, J.W., Xu, L., Denton, J.D. Prediction of low engine order inlet distortion driven resonance in a low aspect ratio fan. ASME Turbo Expo 2000, 45th International Gas Turbine and Aeroengine Technical Congress, Exposition and Users Symposium, Munich, Germany, ASME paper 2000-GT-0374 (May 2000).
C17. Ramesh, O.N., Hodson, H.P. On the dynamics of the calmed region behind a turbulent spot. Minnowbrook III: Boundary Layer Transition and Unsteady Aspects of Turbomachinery Flows, Minnowbrook, Syracuse, New York, USA (August 2000).
C18. Tanaka, K., Kalfas, A.I., Hodson, H.P. Development of single sensor fast response pressure probes. Measuring Techniques in Turbomachinery, Proceedings, 15th Symposium on Measuring Techniques for Transonic and Supersonic Flows in Cascades and Turbomachines, Florence, Italy (September 2000); Edited by G. Manfrida, D. Contini (Università degli di Firenze, 2000). Paper and CD.
C19. Taylor, J., Hynes, T.P. The control of non-axisymmetric flow in axial turbomachinery using circumferentially varying stator exit angles. ASME Turbo Expo 2000, 45th ASME International Gas Turbine and Aeroengine Technical Congress, Exposition and Users Symposium, Munich, Germany, ASME paper 2000-GT-0495 (May 2000).
C20. Vilmin, S., Hodson, H.P., Savill, A.M., Dawes, W.N. Predicting wake passing transition in turbomachinery using a prescribed unsteady intermittency model. European Congress on Computational Methods in Applied Science and Engineering (ECCOMAS), Barcelona, Spain (September 2000).
C21. Wallis, A.M., Denton, J.D., Demargne, A.A. The control of shroud leakage flows to reduce aerodynamic losses in a low aspect ratio shrouded axial flow turbine. ASME Turbo Expo 2000, 45th ASME International Gas Turbine and Aeroengine Technical Congress, Exposition and Users Symposium, Munich, Germany, ASME paper 2000-GT-0475 (May 2000). Published in: Transactions of the ASME, Journal of Turbomachinery, 123, (2), 334-341 (April 2001).
C22. Zhong, S., Kittichaikan, C., Hodson, H.P., Ireland, P.T. Visualisation of turbulent spots under the influence of adverse pressure gradients. Experiments in Fluids, 28, (5), 385-393 (May 2000).
Last modified: September 2001