Design of pre-diffuser cones for dump diffusers for aero gas turbine engines

The main concern of any dump diffuser designer is to design the geometry to achieve the highest possible static pressure recovery within the given envelop of the aero gas turbine engine. In this paper design optimization of dump diffusers with three multiple-steps pre-diffuser divergent cones with the aerodynamically-shaped flame tube have been performed using a validated density based steady standard k-ε turbulence model. The code is validated using the exact solution obtained from the closed-form analytical model of V.R. Sanal Kumar (AIP Advances, 8, 025315, 2018) at the Sanal flow choking condition. This is the continuation of our previous AIAA paper (AIAA 2016-5009). We observed that the boundary layer displacement thickness at the pre-diffuser upstream port is having an effect on the static pressure recovery in the dump diffuser. We also observed that the static pressure recovery can be increased profitably during the flight by designing a dump diffuser with adjustable dump gap facilitated with multiple-steps pre-diffuser cones. We concluded that the dump diffuser with geometrically optimized pre-diffuser upstream port and its divergent cone along with the aerodynamically-shaped adjustable flame tube for attaining variable dump gap effect is a profitable and viable option for improving the performance characteristics of aero gas turbine engines under a wide range of operating conditions. © 2019, American Institute of Aeronautics and Astronautics Inc, AIAA