Investigation On Rarefied Gas Aerodynamic Characteristic Of Reentry Module

Manned spacecraft fly a long time in transitional flow regime during spaceship reentry because of its low lift-to-drag ratio. The effect of rarefied gas characteristics is so serious that affect the aerodynamic characters of reentry module. In order to improve the designing precision of aerodynamic parameter, a set of research system combined with experiment in low density wind tunnel, numerical simulation based on DSMC method and local bridging engineering method is established, which is applied to analyse the rarefied aerodynamics characters of reentry module in transitional flow regime(at altitude 130-70km). The result indicate that viscous effect causes a significant change in aerodynamic characters of reentry module at the rarefied transitional flow flight condition. Each aerodynamic force coefficient and the trim angle reduce with the fall of simulation height. Ca(axial-force coefficient), Cmg(pitching-moment coefficient referenced to reentry module center of gravity) decrease with the angle of attack and Cn(normal-force coefficient), L/D(lift to drag ration) (absolute value) increase with the angle of attack. The maximum of the L/D appear at about 30-degree angle of attack. The bugle of the reentry module drops the trim angle. Pyrochemistry reaction largen Ca, Cn, diminish L/D (absolute value) and the trim angle. The variational tendency of aerodynamic characters with angle of attack in high altitude (higher than 105km) is different from that of in low altitude (lower than 105km).