Research On Internal Waverider Inlet Design For Columniform Forebody Of Aircraft

Inward turning inlet is a special hypersonic inlet type which caused extensive concentrationrecently. IFRC (Internal Flowfield Research Center of Nanjing University of Aeronautics andAstronautics) has developed a new type of inward turning inlet called internal waverider inlet.Numerical simulation and experiment results have proved that this fixed geometry inlet has nicercomprehensive performance compared to sidewall inlet.Based on the pre-work of our research group,a new internal waverider inlet is proposed for high speed missiles, and simulations are taken on/offdesign points. Selection principle for design parameters of the internal waverider inlet is also broughtforward. The main research work that has been done in this paper includes:(1) One of the three design parameters changed, the ICFC basic flowfield performance is obtainedwhen free-stream Mach number is4.0, turn angle being8°and exit Mach number being2.0. Inviscidresults show that the structures of the flowfield are similar. Only alter one design parameter can’t fitfor the selection principle of basic flowfield. Parameters for given inlet design can refer to theseresults.(2) Based on ICFC flowfields, internal waverider inlets are separately designed at M=4.0whoseexit Mach number and turn angle are different in order to match the forebody of high-speed missils.Viscous results show that the inlets have similar structures as the basic flowfields. Turn angle changed,the pressure ratio and total pressure recovery decline, but the latter is still up to0.662; Exit Machnumber changed, pressure ratio declines when the total pressure recovery improves up to0.655. Theflow capture coefficient of the inlets is all above0.992.(3) Investigate the flowfield structures and factors which affect the un-start performance of theinternal waverider inlet at low Mach numbers. CFD results show that the inlets have unique shockstructures and flow characteristics at lower Mach number. Flooding position is one of the mostimportant factors which can affect the start ability of the internal waverider inlet. The start Machnumber reduces from3.6to3.3when the flooding position is changed from sides to bottom, further to3.25with one modular inlet. Besides, the basic flowfield plays an important role in reducing the startMach number. Design exit Mach number fixed, the start Mach number nearly decreases by0.1whenthe turn angle increases by2°with two modular inlets and can reduce to3.1most with one modularinlet. The intake turn angle fixed, the start ability of the inlet is only decided by the internalcontraction ratio. The start Mach number almost reduces by0.2when the design exit Mach number increases by0.2.(4) Investigate the flowfield structures and factors which affect the back pressure performance ofthe internal waverider inlet at different back pressure. An internal waverider inlet is designed whichcan give attention to the performace of design and off-design points. Viscous results show that theinlet can endure70times of the free pressure. Design back pressure being selected as50times of thefree pressure, the back pressure margin is up to40%. Besides, the length or equivalent angle of theexpand segment increases, exit Mach number can reduce more to fit for the engine demand.