![[Univ of Cambridge]](http://www.eng.cam.ac.uk/images/house_style/uniban-s.gif){kind=small}
![[Dept of Engineering]](http://www.eng.cam.ac.uk/images/house_style/engban-s.gif){kind=small}
Computer Aerodynamics
Intermediate Pressure Turbine Aerodynamics
LP Turbine Aerodynamics
Unsteady Flow in High Pressure Steam Turbines
Radial Inflow Turbines
Film Cooling Studies
Instrumentation
High Pressure Steam Turbines
CFD Development
Aerodynamic Optimisation
Transonic Fan Noise
Transonic Fan Design
Combustion Instability
Water Ingestion
Nacelle-Cross Wins Interaction
Non-Axisymmetric Flows
References
There is an increasing trend towards the use of CFD for three-dimensional design and the Whittle Laboratory is in the forefront of this activity, which is performed in very close collaboration with industry(C4). A good example of this type of work is the three-dimensional design philosophy developed a few years ago in collaboration with Parsons Turbine Generators Ltd (now Siemens Power generation UK Ltd). Blading based on this philosophy is now entering service in large steam turbines and is providing outstanding performance.
Professor N.A. Cumpsty
Various aspects of compressor aerodynamics are being investigated. The work on casing treatment for stall delay has been completed, with a better understanding of the mechanisms involved in stall, a clear understanding of how successful treatments work and a treatment capable of delaying stall without losing efficiency. Arising out of the work to design three-dimensional compressor blades is a study of separations and singular behaviour in compressor passages: the usual (two-dimensional) description of separation is inadequate in three dimensions(C9). Another three-dimensional flow being investigated is the behaviour and design of bleed slots, used to remove air to cool hot components, improve handling or pressurise the aircraft.
Professor J.D. Denton
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, is in progress.
A development of the design process is that the new design is being 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 is under way. The whole turbine architecture is being considered, in order to optimise the annulus line, before refining the details of the IP turbine.
Dr H.P. Hodson
A long term study of the unsteady boundary layer development on LP aero-engine turbine blades has led to new designs with considerable fewer blades, with a consequent saving in cost and weight (C5,C6,C8,C10,C11,C12,C15). These blades are already in service on the BMW-Rolls-Royce BR715 engine. The work is being continued in collaboration with ITP of Spain. Fundamental work aimed at improved prediction of unsteady boundary layer transition is in progress in collaboration with Oxford and Leicester Universities. Work aimed at applying the same ideas to compressor blades has recently started.
Dr H.P. Hodson
Research aimed at studying the effects of unsteadiness in turbines is being conducted on the large low speed turbine rig. This is funded by Mitsubishi Heavy Industries Ltd of Japan. The effects of unsteady vortex-blade row interaction on loss are especially interesting and these are being studied by a combination of experiment and CFD(C1).
Dr H.P. Hodson
Research aimed at improving the understanding of the flow through the radial turbines of turbochargers has continued under the sponsorship of IHI of Japan. Detailed experimental and computational examinations have be made of the tip clearance flows(C3). Studies of the effects of changing tip geometry on the overall performance have also been reported. The results have been used to explain existing industrial correlations and to make suggestions regarding future designs.
Dr H.P. Hodson
The combined theoretical-experimental study of the aerodynamic penalties of film cooling continues. Much of the recent work has been aimed at improving the processes involved in the design of cooling geometries for the industrial gas turbines produced by Toshiba of Japan. This work builds directly on the results obtained using experimental techniques that were developed for the determination of film-cooling effectiveness.
Dr H.P. Hodson
An initiative to utilise micro-electronic-mechanical system (MEMS) in miniature and high frequency sensing systems was launched during the year. As well as aiding fundamental research, this is an important step toward the creation of "smart" aero-engines. 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. A novel data reduction algorithm has recently been developed which will allow further miniaturisation(C2,C7).
Professor J.D. Denton
A new set of low reaction blading has been tested in the model HP steam turbine. This is intended as a datum for a new three-dimensional design which is now being produced. As expected, the low reaction design is significantly less efficient that previous, higher reaction, designs of the turbine. The secondary flow in the new design is extremely strong and CFD studies indicate that it is largely due to the interaction of the shroud leakage flow with the next downstream blade row. The detailed flow in both the datum and new design will be measured with particular emphasis on understanding the unsteady flow.
Professor J.D. Denton
Dr L. Xu
The new algorithm, discovered two years ago has at last been successfully incorporated into the multistage steady flow method and is now in widespread use in industry. A shroud leakage model was also incorporated in the method and is starting to show that the importance of the leakage flow has been greatly underestimated. The 3D multistage unsteady code has undergone continued development and is also in widespread use.
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(B11,B12).
Professor W.N. Dawes
The use of steady and unsteady (but conventional) 3D CFD to predict the sources of fan tone noise have been successfully investigated via the EU RESOUND project. Good agreement was obtained with experimental data (FAN PAC) for both pure tones and multiple-tone distortion noise; a new liner model was validated. A follow-on contract, TurboNoise CFD, will couple the CFD prediction of noise sources with duct acoustics via "Smart" boundary conditions.
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 will be tested by Rolls-Royce in early 2000 with measurements of both noise and overall performance. Unsteady calculations of a highly loaded fan operating with inlet distortion have been compared with data from the US Air Force. Some interesting features of the unsteady blade loading have been discovered.
Dr I.J. Day
Combustion instabilities are an undesirable side effect of the lean pre-mixed fueling 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.
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 rows. 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
A study into the effects of cross wind on the flow around civil turbofan nacelles has been started with the aims of elucidating the effectiveness of current methods of cross wind testing and improving prediction methods for the effects of cross winds on fan stall margin.
Dr T.P. Hynes
A method to help in the design of non-axisymmetric stator scheduling for compressors operating in highly asymmetric flow has been developed.
C1. Chaluvadi, V.S.P, Kalfas, A.I., Banieghbal, M.R., Hodson, H.P., Denton, J.D. Blade row interaction in a high pressure turbine. Proceedings, 14th International Symposium on Air Breathing Engines, Florence, Italy (September 1999).
C2. Dambach, R., Hodson, H.P. A new method of data reduction for single-sensor pressure probes. Proceedings, ASME International Gas Turbine and Aeroengine Congress and Exhibition, Indianapolis, IN, USA, ASME Paper 99-GT-304 (June 1999).
C3. Dambach, R., Hodson, H.P. Tip leakage flow in a radial inflow turbine with varying gap height. Proceedings, 14th International Symposium on Air Breathing Engines, Florence, Italy (September 1999).
C4. Denton, J.D., Xu, L. The exploitation of three-dimensional flow in turbomachinery design. Proceedings of the Institution of Mechanical Engineers, Part C, Journal of Mechanical Engineering Science, 213, (C2), 125-137 (1999).
C5. Gostelow, J.P., Hodson, H.P., Walker, G.J. Comparisons between triggered turbulent spots and unsteady transition phenomena on compressor and turbine blading. Proceedings, IUTAM Symposium on Laminar-Turbulent Transition, Sedona, AZ, USA (September 1999).
C6. Harvey, N.W., Cox, J.C., Schulte, V., Howell, R., Hodson, H.P. The role of research in the aerodynamic design of an advanced low-pressure turbine. 3rd European Conference on Turbomachinery: Fluid Dynamics and Thermodynamics, London, 123-132 (March 1999). ISBN 186058196X.
C7. Hodson, H.P., Dambach, R. Single-sensor fast response pressure probes - the "least-squares" method of data reduction. Measuring Techniques in Turbomachines: Proceedings, 14th Symposium on Measuring Techniques in Transonic and Supersonic Flow in Cascades and Turbomachines, Limerick, Ireland; Edited by M. Davies, C. Bryne, T. Dalton (September 1999).
C8. Hodson, H.P., Gostelow, J.P. Similarities in development between triggered turbulent spots and wake-induced turbulent patches. 37th AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, USA, AIAA Paper 99-0404 (January 1999).
C9. Khalid, S.A.., Khalsa, A.S., Waitz, I.A., Tan, C.S., Greitzer, E.M., Cumpsty, N.A., Adamczyk, J.J., Marble, F.E. Endwall blockage in axial compressors. Transactions of the ASME, Journal of Turbomachinery, 121, (3), 499-509 (1999).
C10. Kittichaikarn, C., Ireland, P.T., Zhong, S., Hodson, H.P. An investigation on the onset of wake-induced transition and turbulent spot production rate using thermochromic liquid crystals. Proceedings, ASME International Gas Turbine and Aeroengine Congress and Exhibition, Indianapolis, IN, USA, ASME Paper 99-GT-126 (June 1999).
C11. Ramesh, O.N., Hodson, H.P. A new intermittency model incorporating the calming effect. 3rd European Conference on Turbomachinery: Fluid Dynamics and Thermodynamics, London, 243-258 (March 1999). ISBN 186058196X.
C12. Schulte, V., Hodson, H.P. Prediction of the becalmed region for LP turbine profile design. Transactions of the ASME, Journal of Turbomachinery, 120, (4), 839-845 (1998).
C13. Seifert, A., Hodson, H.P. Periodic turbulent strips and calmed regions in a transitional boundary layer. AIAA Journal, 37, (9), 1127-1129 (1999).
C14. Zhong, S., Kittichaikan, C., Hodson, H.P., Ireland, P.T. A study of unsteady wake-induced boundary-layer transition with thermochromic liquid crystals. Proceedings of the Institution of Mechanical Engineers, Part G, Journal of Aerospace Engineering, 213, (G3), 163-171 (1999).
C15. Zhong, S., Kittichaikan, C., Hodson, H.P., Ireland, P.T. Visualization of turbulent spots and unsteady wake-induced boundary-layer transition with thermochromic liquid crystals. Optics and Laser Technology, 31, (1), 33-39 (1999).
Last modified: June 2000