Emission Control from IC Engines
Prof. K.N.C. Bray
In view of the complexity of many combustion phenomena insight can sometimes be gained by the analysis of combustion processes in simplified geometries. A recent study(B6), which analysed combustion in a laminar Couette flow between two porous plates, exposed the effects of variations in Reynolds number, Mach number and Damköhler number of the flame structure.
Studies have also been made of turbulent combustion processes in more practical situations including flame propagation in the vicinity of walls(B47), autoignition under conditions simulating those in a Diesel engine(B7), combustion and extinction in counterflowing streams with unequal enthalpies(B5) and flames in supersonic flow(B48).
Dr R.S. Cant
Research in computational combustion is growing in strength, and covers a broad range of capabilities in this important area. Two research projects on the Direct Numerical Simulation (DNS) of Combustion are being funded by EPSRC and are providing new data and new insights into the fundamentals of turbulent flames. In addition, new numerical algorithms are being developed in order to meet the severe requirements of DNS in terms of accuracy and computational efficiency. The work employs locally-developed computer codes(B38) and is being carried out on one of the most powerful computers in the country - the Cray T3D at Edinburgh.
In addition, two new research projects sponsored by European Gas Turbines and by Ricardo Consulting Engineers are intended to apply the lessons being learned from DNS to the modelling of combustion in practical systems. Combustion in gas-turbine engines and in spark-ignition automobile engines must be carefully controlled in order to meet increasingly stringent emissions legislation, and computational modelling(B1,B3,B42) has a vital role to play. Locally-developed computer codes are again being used to provide data for model validation and testing.
Recently, a new capability has been developed in collaboration with Professor W.N. Dawes to simulate combustion in geometries of arbitrary complexity(B43): this is now being used to simulate explosions in offshore oil platforms and petrochemical production plants in projects supported by HSE(B12) and Shell Research Ltd(B10,B11).
Dr G.T. Parks
Collaborative research into in-core nuclear fuel management optimisation for Pressurised Water Reactors continued with both Nuclear Electric(B34,B35) and the North Carolina State University Electric Power Research Centre(B33). The outcome of further research into the use of Genetic Algorithms for multi-objective optimisation was also published(B33). Collaborative research with the University of Wisconsin led to publications on the solution of reactor dynamics equations(B4). Research continues into: accuracy of finite difference approximations for variational and perturbation expressions(B29); studies of the financial implications of reliability by Monte Carlo simulation(B8) ; and Monte Carlo methods in neutron transport(B27). Contributions were made to the study of xenon `poisoning' in nuclear reactors, endo-reversible engines(B2) and endo- reversible refrigerators and power plants, and the heating of fluids.
Volume 23 of the annual review series "Advances in Nuclear Science and Technology" was published, co-edited in Cambridge(B26). The monograph on Process Safety(B41) by R.L. Skelton was published by the Institution of Chemical Engineers and is directed to both the undergraduate and graduate areas. The 1995 Annual GKN Lecture in Management that was to have been given by the late Dr John Collier (Managing the Nuclear Industry), having been given for him by Dr C. Smitton, was edited and published.
The year brought instruction in nuclear engineering into the last year of the four-year course. The second year syllabus has been rationalised by cutting out formal lectures on Energy Studies fusion engineering to emphasis operational efficiency and safety aspects.
Dr A.J. Organ
Japanese researchers developing Stirling cycle engines at Kawasaki Heavy Industries have adopted the Cambridge Dynamic Similarity approach to thermodynamic design. A 13 kW engine designed in the UK with the aid of the method is under construction financed by ETSU. The same method has successfully predicted the dynamic behaviour of a `free-piston' machine under development at Oekozentrum (Ecology Centre) Langenbruch, Switzerland. The essence of the Similarity approach has been presented to the European Stirling Forum in Osnabrück(B30,B31,B32).
Dr N. Collings
The activities in the engines group have again been dominated by emissions research. Further studies of the behaviour of a very high frequency response emissions system for unburnt hydrocarbons (originally developed in the department, and now a commercial instrument) have been reported. This work has now become of renewed importance as a second device is now under study for the detection of oxides of nitrogen (NOx) at equally high frequencies. Both these systems are important for resolving the transient emissions behaviour of internal combustion engines.
Modelling of fuel transport in engine inlet manifolds is an important predictive tool, and significant further progress has been made. Continued support from the Ford Motor Company has enabled the group to maintain good facilities for research, and a large new grant for transient emissions test facility was received during the year.
Prof. N.A. Cumpsty
Prof. J.D. Denton
The Whittle Laboratory's experimental and computational resources are applied to improving our knowledge of turbomachinery flows(B16,B18,B19), primarily for application to gas turbines in jet engines. The group is building on its already strong ties with industry and on collaborative ties with overseas teams; the involvement with industry ensures that the work done is of interest and relevance whilst contact with other universities is especially valuable in the training of young researchers.
Unsteady effects are being studied and gradually understood(B9,B28,B37). This understanding has required experimental and computational work; whereas many unsteady effects are undesirable (noise and vibration, for example) it has been found that the effect of wakes from upstream blades can in some cases reduce losses by affecting transition. The combined use of experiment and computation is unravelling the complexities of three-dimensional flow(B17); in turbomachinery the flow is strongly three-dimensional and often includes regions of complicated separated flow. Computational Fluid Dynamics (CFD), using codes written in the Whittle Laboratory, has been used to analyse conventional blades and then design new blades which are predicted to have less separation. These newly designed blades are the subject of experimental confirmation.
The investigation of wet steam effects in turbines has continued theoretically and numerically(B21,B46) on the one hand and experimentally in collaboration with National Power(B44,B45). The experimental results supported the predictions for size of droplets, thermodynamic loss and shock structure.
The CFD software written in the Whittle Laboratory has found wide application by most of the world's turbomachinery manufacturers and the interaction with these companies brings the University considerable financial benefit. The new software includes the understanding resulting from the experimental work. The thrust of the software development is the inclusion of more complicated geometries (such as that around seals and gaps) and the combined flow in multistage machines. To facilitate its use in complicated geometries, generalised meshing algorithms have been developed and links are being built to CAD systems.
B1. ABU ORF, G.M., CANT, R.S. Reaction rate modelling for premixed turbulent methane air flames. Proceedings, Joint Meeting, Portuguese, British, Spanish and Swedish Sections of the Combustion Institute, Funchal, Madeira (April 1996).
B2. ALLAGI, M. Accuracy of Monte Carlo studies of multiplication factors. Universities Nuclear Technology Forum, London (April 1996).
B3. BARSANTI, P.S., BRAY, K.N.C., CANT, R.S. Modelling of confined turbulent explosions. In: Dynamics of Exothermicity; Edited by J.R. Bowen, 13-52 (Gordon and Breach, Amsterdam, 1996).
B4. BASKEN, J., LEWINS, J.D. Power series solutions of the reactor kinetics equations. Nuclear Science and Engineering, 122, (3), 407-416 (1996).
B5. BRAY, K.N.C., CHAMPION, M., LIBBY, P.A. Extinction of premixed flames in turbulent counterflowing streams with unequal enthalpies. Combustion and Flame, 107, (1/2), 53-64 (1996).
B6. BRAY, K.N.C., CHAMPION, M., LIBBY, P.A. Premixed combustion in laminar Couette flow. Combustion and Flame, 104, (3), 241-259 (1996).
B7. CHANG, C-S., ZHANG, Y., BRAY, K.N.C., ROGG, B. Modelling and simulation of autoignition under simulated diesel engine conditions. Combustion Science and Technology, 113-114, 205-219 (1996).
B8. CHANG, M. The embarrassment of a safety engineer: optimising life cycle revenue loss. Universities Nuclear Technology Forum, London (April 1996).
B9. CHERRETT, M.A., LYES, P.A., LONGLEY, J.P., DEMARGNE, A.A.J. Measurement and calculation of instability inception in a high-speed multi-stage compressor. Unsteady Flows in Turbomachines, Von Karman Institute Lecture Series 1996-05, 11-15 (March 1996).
B10. CONNELL, I.J., WATTERSON, J.K., SAVILL, A.M., DAWES, W.N. Predicting the SOLVEX box confined explosion test case with an unstructured adaptive mesh code. Abstracts, 26th Combustion Institute Symposium, Naples, Italy (July 1996).
B11. CONNELL, I.J., WATTERSON, J.K., SAVILL, A.M., DAWES, W.N. An unstructured adaptive mesh Navier-Stokes solution procedure for predicting confined explosions. Abstracts, 19th IUTAM International Congress of Theoretical and Applied Mechanics, Kyoto, Japan (August 1996).
B12. CONNELL, I.J., WATTERSON, J.K., SAVILL, A.M., DAWES, W.N., BRAY, K.N.C. An unstructured adaptive mesh CFD approach to predicting confined premixed methane-air explosions. Proceedings, 2nd International Specialists Meeting on Fuel-Air Explosions, CMR Bergen (May 1996).
B13. COWLEY, M.D. On natural convection in rectangular enclosures with arbitrary orientation and vertical magnetic field. 14th International Conference on Magnetohydrodynamics, Jurmala, Latvia (August 1995).
B14. CUMPSTY, N.A. Aeronautical and aerospace achievements of the United States: internal and external influences on a success story (Book review of `Flight in America', by R.E. Bilstein). Minerva, 33, 193-208 (1995).
B15. CUMPSTY, N.A. Axial flow compressors. In: Handbook of Fluid Dynamics and Fluid Machinery, Volume III: Applications of Fluid Dynamics; Edited by J.A. Schetz, A.E. Fuhs, Section 27.4, 2288-2317 (John Wiley, New York, 1996).
B16. CURTIS, E.M., HODSON, H.P., BANIEGHBAL, M.R., HOWELL, R.J., HARVEY, N.W. Development of blade profiles for low pressure turbine applications. 41st ASME International Gas Turbine and Aeroengine Congress, Birmingham, ASME paper 96-G-358 (June 1996).
B17. DENTON, JD. Lessons from rotor 37. Keynote address. 3rd International Symposium on the Aerothermodynamics of Internal Flows, Beijing, China (September 1996).
B17. DENTON, J.D. Turboexpander. A design, make and test student project. 41st ASME International Gas Turbine and Aeroengine Congress, Birmingham ASME paper 96-GT-191 (June 1996).
B19. DENTON, J.D., SUTTON, A.J. The influence of trailing edge shape and boundary layer thickness on the trailing edge loss of subsonic turbine blades. 3rd International Symposium on the Aerothermodynamics of Internal Flows, Beijing, China (September 1996).
B20. EMERSON, D.R., CANT, R.S. Parallel direct numerical simulation of turbulent combustion on MPP systems. 6th International Conference on Numerical Combustion, New Orleans, LA (March 1996).
B21. HUANG, L., YOUNG, J.B., An analytical solution for the Wilson point in homogeneously nucleating flows. Proceedings of the Royal Society of London, Series A, 452, 1459-1473 (1996).
B22. HUNTSMAN, I., HODSON, H.P. Boundary layer development in a radial inflow turbine at off design flow conditions. 12th International Symposium on Air Breathing Engines, ISABE, Melbourne, Australia (September 1995).
B23. HUNTSMAN, I., HODSON, H.P. A laminar flow rotor for a radial inflow turbine, AIAA Journal of Propulsion and Power, AIAA, 11 (6), 1170-1178 (1995).
B24. LEWINS, J.D. Nip or tuck, rip and chuck. Letter to Editor. Kipling Journal (1995).
B25. LEWINS, J.D. Turning on the hot tap: the art of the analyst. Annals of Nuclear Energy, 23, (4/5), 355-370 (1996).
B26. LEWINS, J.D., BECKER, M. (Editors). Advances in Nuclear Science and Technology, 23 (Plenum, New York, 1996).
B27. LEWINS, J.D., NGCOBO, E.N.N. Property discontinuities in the solution of finite difference approximations to the neutron diffusion equations, Annals of Nuclear Energy, 23, (1), 29-34 (1996).
B28. LONGLEY, J.P., SHIN, H-W., PLUMLEY, R.E., SILKOWSKI, P.D., DAY, I.J., GREITZER, E.M., TAN, C.S., WISLER, D.C. Effects of rotating inlet distortion on multistage compressor stability. Transactions of the ASME, Journal of Turbomachinery, 118, (2), 181-188 (April 1996).
B29. NGCOBO, E.N. Calculations of ratios in critical systems. Universities Nuclear Technology Forum, London (April 1996).
B30. ORGAN, A.J. The great Stirling cycle simulation fraud. Proceedings, European Stirling Forum, Osnabrück, Germany, 246-269 (February 1996).
B31. ORGAN, A.J., MAECKEL, P. `Connectivity' and regenerator thermal shorting.
Proceedings, European Stirling Forum,
Osnabrück, Germany, 229-243 (February 1996).
B32. ORGAN, A.J., MAECKEL, P. Gas particle temperature loci for exploring Stirling machine operation. Proceedings, European Stirling Forum, Osnabrück, Germany, 214-218 (February 1996).
B33. PARKS, G.T. Multiobjective pressurized water reactor reload core design by nondominated genetic algorithm search. Nuclear Science Engineering, 124, 178-187 (1996).
B34. PARKS, G.T., KNIGHT, M.P. Loading pattern optimisation in hexagonal geometry using PANTHER. Proceedings, International Conference on the Physics of Reactors, PHYSOR 96, Mito, Japan, 3, I.66-I.75 (September 1996).
B35. PARKS, G.T., KNIGHT, M.P. Pressurised water reactor fuel management using PANTHER. Nuclear Engineer, 37, (4), 104-108 (1996).
B36. PROSSER, R, CANT, R.S. Assessment of numerical methods for direct numerical simulation of turbulent combustion. 6th International Conference on Numerical Combustion, New Orleans, LA (March 1996).
B37. ROBERTS, Q.D., DENTON, J.D. Loss production in the wake of a simulated turbine blade. 41st ASME International Gas Turbine and Aeroengine Congress, Birmingham, ASME Paper 96-GT-421 (June 1996).
B38. SCHLICK, T., PARKS, G.T. Mathematical optimization. In: Computational Science Education Project, 2nd edition; Edited by C.E. Oliver, M.R. Strayer, V.M. Umar, D. Zachmann, J. Conery USA Department of Energy Educational Program Electronic Publication, web address: http://csep1.phy.ornl.gov/csep.html (1996).
B39. SCHULTE, V.S., HODSON, H.P. Unsteady wake induced boundary layer transition in highly loaded LP turbines. 41st ASME International Gas Turbine and Aeroengine Congress, Birmingham, ASME paper 96-GT-486 (June 1996).
B40. SELIM, M.Y.E., COLLINGS, N., Turbulence structure and decay in a model engine: effects of inlet conditions. Society of Automotive Engineers International Congress and Exposition, Detroit, MI, SAE paper 961189 (February 1996).
B41. SKELTON, R.L. Process Safety Analysis: an Introduction. (Institution of Chemical Engineers, 1996).
B42. WATKINS, A.P., LI, S.P., CANT, R.S. Premixed combustion modelling for spark ignition engine applications. Society of Automotive Engineers International Spring Fuels and Lubricants Meeting, Dearborn, MI, SAE paper 961190 (May 1996).
B43. WATTERSON, J.K., SAVILL, A.M., DAWES, W.N., BRAY, K.N.C. Predicting confined explosions with an unstructured adaptive mesh code. Proceedings, Joint Meeting of the Portuguese, British, Spanish and Swedish Sections of the Combustion Institute, Funchal, Madeira (April 1996).
B44. WHITE, A.J., YOUNG, J.B. Loss measurements and the interpretation of pitot pressures in two phase vapour droplet flows. In: Proceedings, 1st International Symposium on Two Phase Flow Modelling and Experimentation, Rome, Italy (October 1995); Edited by G.P. Celat and R.K. Shah, 1, 593-600 (Edizioni ETS, 1995).
B45. WHITE, A.J., YOUNG, J.B., WALTERS, P.T. Experimental validation of condensing flow theory for a stationary cascade of steam turbine blades. Philosophical Transactions of the Royal Society of London, Series A, 354, 59-88 (1996).
B46. YOUNG, J.B. Wet steam research at Cambridge 1980-1995. Electric Power Research Institute Workshop on Moisture Nucleation in Steam Turbines, Rochester, NY (October 1995).
B47. ZHANG, Y., BRAY, K.N.C., ROGG, B. Temporally and spatially resolved investigation of flame propagation and extinction in the vicinity of walls. Combustion Science and Technology, 113-114, 255-271 (1996).
B48. ZHENG, L.L., BRAY, K.N.C. Effects of laminar flamelet structures on supersonic turbulent combustion. Proceedings, IUTAM Symposium on Combustion in Supersonic Flows; Edited by M. Champion, B. Deshaies, 111-117 (Kluwer Academic, 1996).