Computational Modeling of T5 Laminar and Turbulent Heating Data on Blunt Cones, Part 1 : Titan Applications

A series of shots were run in the T5 shock tunnel at the California Institute of Technology to measure laminar and turbulent heating levels on a 70° blunt cone at three angles of attack in an environment representative of an aerocapture mission at the Saturn moon Titan. The data from 44 shots arc presented over a range of enthalpies and stagnation pressures. The data include laminar, transitional, and turbulent flows. The CFD matches well with the low pressure, laminar, data for all enthalpies and angles-of-attack. The data is best matched by assuming a fully-catalytic wall, however the difference between non-catalytic and catalytic heating are small for these conditions. The CFD does not well match the data obtained at high pressures The high pressure data show augmented heating rates in the stagnation region of the flow field for all angles-of-attack. The CFD does not indicate such a heating augmentation, and thus underpredicts the stagnation region heating levels. The underlying physical mechanism for the stagnation region augmentation has not been identified, and it is not clear if this phenomenon is unique to ground test facilities or if it also occurs in flight. The data indicate that smooth wall transition occurs at values of Re&e between 300 and 400 independent of angle-of-attack and enthalpy. It is also confirmed that the parameter Refle better collapses the smooth wall transition data for all angles-of-attack as compared to the parameter Ree.