Aerodynamic Interactions of Reaction-Control-System Jets for Atmospheric Entry Aeroshells

Abstract

The fluid interactions produced by a sonic reaction-control-system thruster are investigated using computational fluid dynamics. The study uses a scaled Mars Science Laboratory aeroshell at a 20 deg angle of attack in Mach 12 flow of -seeded gas. The reaction-control-system jet is directed either parallel or transverse to the freestream flow to examine the effects of the thruster orientation. The results show that both the parallel and transverse reaction-control-system jets obstruct the flow around the aeroshell and impinge on the surface, increasing the overall pressure along the aftbody. As a result, the reaction-control-system jet decreases the drag, lift, and moment acting on the aeroshell, particularly at relatively large reaction-control-system thrust conditions. The results also indicate that the fluid interactions produced by the parallel and transverse jets affect the control effectiveness of the reaction control system. The performance of the parallel reaction-control-system thruster is close to ideal due to relatively small aerodynamic interference induced by the jet. However, the relatively large aerodynamic interference produced by the transverse reaction-control-system jet causes a deficit of control authority. The physical accuracy of the computational method is assessed by comparing the numerical results with experimental visualizations.