New conception of aerothermal protection for hypersonic vehicles

High speed vehicles are designed to withstand severeaerodynamic heating conditions. Such vehicles include hypersonicprojectiles, reentry payload module and hypersonic aircraft. Maximum heatingand the consequent possibility for material erosion are typical problemsassociated in the nose region of the blunt body. The blunt nose shape alsoleads to very high aerodynamic drag accompanied by high structural pressureloadings, which exhibit significant effects in the final performance of thevehicle. So, there will be a trade-off study between thermal protectionsystem and high wave drag associated with shock wave formation on such highspeed vehicles.Waverider is favorable configuration for hypersonic aircrafts in terms ofthe high lift-to-drag ratio and integration design facility. However, theirsharp leading edge brings severe aero-heating problem, which seriouslyhinders them from practical applications. Current literatures aboutaerothermal protection for waveriders mainly focus on the leading edgeblunting. However, these researches are all motivated by aerothermalconsideration, and the requirements of high lift-to-drag ratio greatlylimits the bluntness of the leading edge, thus the effectiveness inaeroheating protection. In other words, the blunting of waverider's leadingedges seems a theoretically possible way to relieve aeroheating. Under thisbackground, the ``artificially blunted leading edge (ABLE)'' concept isfirst introduced into the waverider design in the present paper, expected topreserve a relatively sharp leading edge on the aerodynamic aspect, whileshowing virtual blunt leading edge on the aerothermal aspect, so as to finda new and effective way for waverider aerothermal protection.After a comprehensive formal parameter definition of the ABLE waverider, theinfluences of the parameters on the aerodynamic and aerothermalcharacteristics are investigated by means of the CFD numerical simulation.Basing on the flow analysis, with a circuitous process, feasibletwo-dimensional ABLE waverider configurations are finally obtained, and therules and disciplines of the aerothermal protection method for waveridersusing the ABLE concept are concluded. The results show that, if designedproperly, the maximum heat transfer rate can be reduced by 60\% or so,with a lift-to-drag ratio loss of no more than 19\%, compared to thecorresponding normal waverider configuration. Furthermore, the effectivenessis believed to be better with integral optimization of the ABLE formalparameters.