Modeling of Shock Tunnel Aeroheating Data on the Mars Science Laboratory Aeroshell

Abstract

A series of shots are run in the T5 shock tunnel at California Institute of Technology to measure heating levels on a 70 blunt cone at angle of attack in an environment representative of the Mars Science Laboratory entry. Twenty shots are obtained in CO 2 over a range of enthalpies and pressures chosen to span the laminar and turbulent flow regimes. The data indicate that the lee side turbulent heating augmentation predicted by flight simulations is valid and must be accounted for during the design of the thermal protection system. Computational fluid dynamic simulations are generally in good agreement with the laminar data when employing a supercatalytic wall model, whereas turbulent simulations are in reasonable agreement when a noncatalytic wall model is used. The reasons for this discrepancy are unknown at this time. The turbulent heating augmentation is shown to be inversely related to freestream enthalpy. Changes in angle of attack between 11 and 16 are shown to have minimal impact on measured and computed heating. A transition criterion based on momentum thickness Reynolds number, analogous to that used in flight predictions, predicts onset with reasonable accuracy, although transition is observed to occur later than the current design criterion indicates.