Computation of radiative and convective contributions to Viking afterbody heating

Abstract

This paper investigates the hypothesis that the observered gap between CFD and thermocouple-derived flight measurements for afterbody heating of the Viking spacecraft can be accounted for by infrared radiation from CO2 molecules in the wake flow. The DLR TAU code is implemented to simulate the Viking I spacecraft at an altitude of 37.4km on a flow-adapted hybrid 3D grid with radiation- flowfield coupling. The radiation spectrum of the CO2 molecule is represented by a statistical narrow band model and radiation transport is calculated via an opacity-binned ray-tracing model. The calculated total heating level on the aluminium base cover is in good agreement with the flight data, while the total heating level for the fiberglass cover is overpredicted. Furthermore, radiation-flowfield coupling is found to reduce the total heat flux on the vehicle surface by up to 10% compared to when radiation is treated in an uncoupled manner.