A new idea of drag reduction and thermalprotection for hypersonic vehicles is proposed based on thecombination of a physical spike and lateral jets for shock-reconstruction. The spike recasts the bow shock in front ofa blunt body into a conical shock, and the lateral jets workto protect the spike tip from overheating and to push theconical shock away from the blunt body when a pitchingangle exists during flight. Experiments are conducted in ahypersonic wind tunnel at a nominal Mach number of 6. Itis demonstrated that the shock/shock interaction on the bluntbody is avoided due to injection and the peak pressure atthe reattachment point is reduced by 70% under a 4°attackangle.
Zonglin Jiang Yunfeng Liu Guilai Han Wei Zhao Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, 100190 Beijing, China
A 'swallowtail' cavity for the supersonic com-bustor was proposed to serve as an efficient flame holderfor scramjets by enhancing the mass exchange between thecavity and the main flow.A numerical study on the 'swallow-tail' cavity was conducted by solving the three-dimensionalReynolds-averaged Navier-Stokes equations implementedwith a k-e turbulence model in a multi-block mesh.Turbu-lence model and numerical algorithms were validated first,and then test cases were calculated to investigate into themechanism of cavity flows.Numerical results demonstratedthat the certain mass in the supersonic main flow was suckedinto the cavity and moved spirally toward the combustorwalls.After that,the flow went out of the cavity at its lateralend,and finally was efficiently mixed with the main flow.The comparison between the 'swallowtail' cavity and theconventional one showed that the mass exchanged betweenthe cavity and the main flow was enhanced by the lateralflow that was induced due to the pressure gradient inside thecavity and was driven by the three-dimensional vortex ringgenerated from the 'swallowtail' cavity structure.
