Assessment of Reflected Shock Tunnels for Mars Entry Vehicle Ground Testing

Hypervelocity Spherically-Blunted Cone Flows in Mars Entry Ground Testing

“…One standard deviation in the standoff distance measured in the movies is taken to be the uncertainty in standoff distance for these experiments. Experimental repeat measurements were within these ranges [33]. This corresponds to standard deviations in standoff distance measured from the high-speed videos during the experimental test time of 4.0 and 4.2% for the sphere experiments, and 8% for the sphere-cone experiment [34].…”

“…A simulation was performed for each test using the experimentally measured reservoir pressure and shock velocity. A more detailed description of the method used to obtain the freestream conditions in T5 can be found in Leibowitz and Austin [33] and Leibowitz [34]. Experiments were conducted with a contoured nozzle that produces nominally uniform flow at the exit plane as well as a conical nozzle that produces diverging flow at the exit plane.…”

“…The body location was defined by the maximum gradient in intensity near the body. This method was used to extract standoff distance from high-speed images in Leibowitz and Austin [33].…”

“…A detailed evaluation of the sensitivity of the numerical shock standoff distance to the variations in steady nozzle exit prediction due to uncertainty in experimental measurements of shock speed and reservoir pressure found up to 3.8% variation in standoff distance for the T52886, 1 in. sphere experiment [33].…”

Numerical and Experimental Study on the Duration of Nozzle Starting of the Reflected High-Enthalpy Shock Tunnel

“…It also takes some time to start up the model, which will further shorten the efficient test time [16,17]. The T5 high-enthalpy shock tunnel at GALCIT (Graduate Astronautics Laboratory, California Institute of Technology, Pasadena, CA, USA) [18] extended the duration by enlarging the equipment, but the effective test duration is still only 1 ms when it is running in high-enthalpy conditions (the total enthalpy is greater than 20 MJ/kg) [19,20]. Other well-known shock tunnels in the world, such as the HEG (High Enthalpy shock tunnel Göttingen) in Germany and HIEST (High-Enthalpy Shock Tunnel) in Japan, when operating under high-enthalpy conditions, the effective test duration is also around 1 ms [21][22][23][24].…”