Abstract:

Combined with the LU SGS implicit scheme and MUSCL interpolation method, Roe's approximate Riemann scheme is applied to develop a code for 3 D compressible Navier Stokes equations. With this code the flow field structure and aerodynamic performance of a dual swept/dual ramp inlet under ground running are investigated, and the effect of the fuselage and LEX is considered in this calculation. The results calculated show that: (a) Large scale separation occurs at the fore part of the bottom outside corner, which is the cause of large total pressure distortion at the exit section. (b) The secondary flow at the cross section in the fore part of the inlet behaves as two counter rotating vortices: the clockwise one is stronger, governing the up outside corner, while the anti clockwise one is weaker, governing the bottom inside corner; at the outlet section, the secondary flow behaves as a bulk swirl. (c) As a result of the swirling flow, the high and low total pressure zones are rotated markedly. Furthermore, comparisons of the CFD results and experiment results are made to validate the reliability of the code used in this paper.

Key words: dual-swept / dual-ramp, inlet, separated flow, ground running, swirling flow, distortion