Supersonic Retropropulsion Validation Experiment in the NASA Langley Unitary Plan Wind Tunnel

The development of supersonic retropropulsion, an enabling technology for heavy payload exploration missions to Mars, is the focus of the present paper. A new experimental model, intended to provide computational fluid dynamics model validation data, was recently designed for the Langley Research Center Unitary Plan Wind Tunnel test section 2. Pretest analyses using modern computational fluid and thermal analysis tools were instrumental for sizing., and refining the model, over the Mach number range of 2.4-4.6, such that tunnel blockage and internal flow separation issues would be minimized. A 5-in.-diam 70 deg sphere-cone forebody, which accommodates up to four 4 : 1 area ratio nozzles, followed by a 9.55-in.-long cylindrical aftbody, was developed for this study based on the computational results. The model was designed to allow for a large number of surface pressure measurements on the forebody and aftbody. Supplemental data included high-speed schlieren video and internal pressures and temperatures. The run matrix was developed to allow for the quantification of various sources of experimental uncertainty, such as random errors due to run-to-run variations and bias errors due to flowfield or model misalignments Observations and trends from this initial test in the Unitary Plan Wind Tunnel are presented.