Investigations of Peripheral Propulsive Deceleration Jets on a Mars Science Laboratory Aeroshell

Abstract

The objective to send more massive landed missions to the surface of Mars necessitates further research and development for ways to adequately decelerate the lander, such as propulsive deceleration. Experimental measurements using planar laser-induced iodine fluorescence provide qualitative visualizations and quantitative propulsive decelerator jet mole fraction measurements over a 0.22% scaled Mars Science Laboratory aeroshell. Peripheral (off-centerline) sonic and supersonic propulsive decelerator jet models, with jet exit velocities of Mach 1.0 and 2.66, were studied in Mach 12 flow and compared with numerical results obtained using computational fluid dynamics. Experimental visualizations were obtained for various thrust coefficients ranging from 0.5 to 3.0 in increments of 0.5. Experimental results indicate that, for both sonic and supersonic jets, the bow shock is preserved between the peripheral jets and, as thrust coefficient increases, the bow shock is pushed farther from the aeroshell forebody, with the supersonic jets having a greater shock standoff distance than sonic models at thrust coefficient greater than 2.0. Comparisons of the experimental visualizations to computed streamlines and shock locations show good agreement. Computed propulsive decelerator jet mole fractions for both sonic and supersonic thrust coefficient of 1.5 closely match experimental results through the jet cores and in cross-sectional cuts.