Studies on Dump Diffusers with Aerodynamically-shaped Adjustable Flame-tubes for Modern Aircraft Engines

摘要

Gas turbine engines need diffusers to slow down the air between the high pressure compressor and the flame tube. It is inevitable that the diffuser designer has to produce it in the shortest possible length with the highest possible static pressure recovery and with a pressure distribution that is uniform around the combustor dome so as to minimize the pressure losses and enhance combustion stability using a dump diffuser. In this paper numerical studies on an annular combustor dump-diffuser with aerodynamically-shaped flame tube have been carried out using a validated 3D density based steady standard k-ε turbulence model to investigate the infulences of: pre-diffuser geometry, dump gap, and flame tube geometry. We observed that for a wide range of operating conditions an aerodynamically efficient adjustable flame tube coupled with an efficient prediffuser geometry warrant high static pressure recovery. We concluded that the prudent optimization, under aerodynamic constraints, of a pre-diffuser with an adjustable flame tube, with respect to dump gap and orientation, may be a future viable option for warranting high performance diffusers with maximum static pressure recovery under a wide range of operating conditions for modern aero-gas turbine engines.