University Associate Professor

Academic Division: Energy, Fluids and Turbomachinery

Research group: Turbomachinery

Telephone: +44 1223 3 37583

Email: jpl@eng.cam.ac.uk

Research interests

Dr Longley's research interests include:

Flow Disturbances in High-Speed Compressors - The stability of flow through high-speed multi-stage axial flow compressors is of major interest both in the design and development of all types of gas turbines. The flowfield breakdown mechanisms are relatively well understood in low-speed compressors whilst in high-speed compressors much research remains to be done. Modelling techniques are well established for low-speed compressors and one suitable for high-speed compressors has been developed. A recently completed BRITE/EURAM funded research project into stall in high-speed compressors has provided a lot of new experimental observations and comparisons with the theoretical model have been very. Work is now being undertaken to advance the high-speed compressor modelling technique to account for radial flow variations.

Mainstream and Stator-Shroud Leakage Flow Interaction - The leakage flow beneath the stator-shroud in aeroengine compressors introduces several engineering problems: drum heating, windage losses and reduced blade row efficiency. The topic of this research project is the interaction between the seal leakage flow and the mainstream aerodynamics. Preliminary information suggests that there can be a substantial effect on the blade row loss coefficient associated with even a small amount of leakage flow. A experimental and computational project is being funded by EPSRC and Rolls-Royce into this problem. Large scale low-speed cascade experiments, single stage compressor measurements and calculations using Dawes unstructured NEWT code will be undertaken.