Heat Dissipation using Minimum Counter Flow Jet Ejection During Spacecraft Re-Entry

A major problem of spacecraft re-entry is the extreme heat generated. Sink and ablation cooling are commonly used but the cost of building and implementing such heat protection systems is very high. The issue of heat dissipation has, therefore, been an extensive area of research. Various passive and active methods of flow control have been attempted. Unfortunately, no viable cost effective methodologies have yet been possible to develop. At the University of New South Wales, various methods of active flow control technologies for application to subsonic and supersonic flows with a bias towards higher efficiency and lower energy usage are been explored. In this paper, a new approach of deploying minimum counter flow jet ejection as an active flow control method for heat dissipation is attempted. The concept relies on imparting sufficient momentum on the strong bow shock wave formed to induce oscillation but low enough to avoid instability during the flow interaction. To test the concept, an Apollo command module has been employed. It has been subjected to a free stream Mach number of 3 and a two-dimensional numerical flow simulation using ANSYS as the computational fluid dynamics tool has been performed for several cases of counter flow jet injection imparted on the bow shock wave formed and the interaction with the oncoming flow through the frontal stagnation point of the test module and compared with no injection case. Results obtained are highly promising. It appears that substantial heat reduction on the body is possible using the new approach. This finding may be of high practical significance and open up the possibility of developing a new thermal protective system using active flow control of dissipating and reducing heat during spacecraft re-entry with minimum energy input.