Investigation Of2D Hypersonic Inlet Starting And Off Design Performance Estimation

The Hypersonic inlet starting is a crucial issue for air breathing propulsion system, which deter-mines the flight mission success or failure. While air vehicles not always stay at design point, theperformances of inlet at off-design state are also important for the aircraft. At present, these two issueshave received a lot of attractions for the reason that they have important theoretical and practical val-ues.Firstly, the supersonic flow-field establishment process during the2D hypersonic inlet in theshock tunnel has been numerical investigated; a mathematical model of the double-shocks structurehas been performed. And several typical stages have been selected to study the detailed flow-fieldcharacteristics. In addition, according to the theoretical model, it found that initial conditions havesignificant impact on the inlet pulse-starting ability which mainly caused by transforming the strengthof the double-shocks.Secondly, a one-dimensional unsteady method of characteristics was used to build the theoreti-cal model of over-speeding process. Then a2D hypersonic inlet was used to study the flow-fieldchanging during the over-speeding starting process. Different Mach-number accelerations and internalcontraction ratios were considered to analysis the over-speeding self-starting ability. According to theCFD results of different internal contraction inlets, a self-starting Mach number empirical formula hasbeen present.At last, a typical hypersonic inlet design program has been carried out. In virtue of the effect ofboundary layer, which lead to amount of mass spillage, a new method of viscous modification havebeen present, which can improve mass capture ability about5%compared with using the methodbased on inviscid gas dynamic equations. Then parameterization studies generated by Optimal LatinHypercube have been carried out. Some of the flight conditions as well as geometry parameters havebeen considered. Through theoretical formulas and massive numerical simulations, the performancesof the external compression stage and the whole inlet that including these factors have been gain by Aestimation program and empirical equations, which are accurate within±5%and±10%compared tothe CFD results, respectively. In conclusion, the estimation program and empirical equations for theinlet at off-design state have certain credibility.