エアフィルムによる再突入機体ブラックアウト低減化の非定常解析

抄録

During reentry into the planetary atmosphere, the vehicle is surrounded by ionized and dissociated plasma caused by aerodynamic heating. The high-dense plasma near the vehicle blocks the electromagnetic wave propagation for telecommunication, and then, communication with the ground station is prevented. This problem is known as a reentry blackout. One method of mitigation of reentry blackout is air film technique, in which low-temperature gas is blown out of the vehicle to form a path for electromagnetic waves propagation. In this study, to clarify the effect of air film for blackout mitigation, the plasma flow around an experimental model conducted in the DLR was reproduced by a computational fluid dynamics approach. In the present analysis, three cases with different mass flow rates were analyzed. In the two cases with low mass flow rates, oscillations of the air film were observed. In the case with the highest mass flow rate, the results approached steady state with time. This indicated that a high mass flow rate can ensure a stable low electron number density region and mitigate reentry blackouts. In the future, it is necessary to apply the effect of air film to the reentry capsule shape and evaluate the effect on the mitigation of communication blackout and aerodynamic characteristics.