Experimental and Numerical Study of Laminar and Turbulent Base Flow on a Spherical Capsule

A review is presented of ground test measurements on a spherical capsule model with aftbody measurements of heating and pressure for a range of enthalpies and Reynolds numbers to obtain datasets of fundamental validation data for CFD codes and to develop a database for design-of-experiment of future studies. These measurements have been made using several sting mounting arrangements and significant differences in heating of up to 100% have been observed. Increasing relative heat transfer with increasing Reynolds numbers has been observed which may be indicative of transitional behavior on the aftbody. The relative heating on the aftbody has also been found to be exceptionally sensitive to the flow total enthalpy. Measurements of jet and cavity interaction on the otherwise smooth aftbody have also been explored and a non-dimensional correlation developed for design of future test articles. Finally, comparisons with the US3D code using a DES methodology have been made with the data and generally good agreement to within one standard deviation has been found. The most significant limitations have been found in modeling transition and in matching heating and pressure locally near separation points.