Conceptual study on non-ablative TPS for hypersonic vehicles

Abstract

In order to achieve efficient wave drag reduction under non-zero attack angles and avoid the severe aerodynamic heating, a new concept of the Non-ablative Thermal Protection System (NaTPS) for hypersonic vehicles was proposed based on the idea that the conical shock wave angle can be enlarged by lateral jets to push the conical shock away from the blunt body surface. In the NaTPS, a spike-blunt body structure and lateral jets are combined together to develop a new shock-reconstructing system in front of hypersonic vehicles. When the spike acts to recast the bow shock in front of a blunt body into a conical shock, the lateral jet works to protect the spike tip from overheating and push the conical shock away from the blunt body when a pitching angle exists during flight. The experimental flow visualization and the pressure measurements were conducted in a hypersonic wind tunnel for both the conceptual demonstration and CFD validation. Numerical simulations were also carried out to examine the complex flow around the NaTPS. Both experimental and numerical results show that the NaTPS works well for shock drag reduction and thermal protection. The shock/shock interaction on shoulders of the blunt body is avoided due to lateral jet injection and the peak pressure at the reattachment region is reduced by 65% under a 4° attack angle. The lateral jet could be powered either by high pressure gas stored in the tank or by the water evaporation process in which water absorbs the heat from the hot walls of the blunt noses. The jet pressure needed for producing lateral jet is much smaller than for the forward-facing jet from the stagnation point. The advantages of this concept are well demonstrated and its practical application appears promising.