Investigation of the Interactions of Reaction Control Systems with Mars

Interactions between the Reaction Control System (RCS) jets and the bow shock from the aeroshell of a Mars Science Lab (MSL) model are investigated. Images are obtained experimentally at the University of Virginia using a low-density, hypersonic wind tunnel with the Planar Laser Induced Iodine Fluorescence technique. The models are.44% MSL aeroshells fitted with 0.5 mm RCS orifices to simulate Reaction Control Systems in both parallel and transverse jet directions relative to the aeroshells. Experiments are conducted at Mach 12 in the underexpanded jet freestream flowfield with sonic RCS jets. Images for both transverse and parallel jets are obtained for nozzle-thrust coefficients ranging from 0 to 3. It is found that there is much interaction between the aeroshell bow shock and the RCS jet for the transverse jet cases; however, there was not much interaction between the parallel jet and the bow shock on the aeroshell. Results from a nozzle-thrust coefficient of 0.5 were compared to numerical simulations for similar conditions obtained using CFD at the University of Michigan. It is found that there is good agreement in flowfield density between the experimental and numerical results in the jet core of the RCS but greater differences near the jet boundaries. I