关键词: RANS/LES方法, 突起物, 激波/边界层干扰, 超声速流动, 数值模拟

Abstract:

The protuberances fixed on a supersonic aircraft such as aerofoil or rudder may cause complex shock wave/boundary layer interactions which can greatly affect the aerodynamic characteristics around the protuberances or even in the whole aircraft. Traditional computational fluid dynamics (CFD) numerical methods solving Reynolds-averaged Navier-Stokes (RANS) equations cannot forecast the turbulence pulsating flow accurately. In this paper, a novel mixed RANS/LES (Large Eddy Simulation) model is developed based on the study of the merits and demerits of the B-L (Baldwin-Lomax) model and Smagorinsky model. Then it is applied to simulate the flow of the protuberances fixed on a rocket. Such flow phenomena as shock wave/boundary layer interaction, shear layer instability and separation vortex are depicted meticulously. The pressure pulsation process on the protuberance surface is obtained, and it is subsequently used to make a frequency spectrum analysis. Result indicates that the shock wave/boundary layer interaction rather than the bottom separation vortex is the main factor causing the pressure pulsation on the protuberance,. and this pressure vibration may affect badly the normal operation of the equipment in the rocket.

Key words: RANS/LES method, protuberance, shock wave/boundary layer interaction, supersonic flow, numerical simulation