Aerodynamic Configuration Design And Numerical Simulation Of Hypersonic Vehicles Based On A Geometric Integrated Methodology

This paper is aimed at investigating concept design and aerodynamic performance analysis methodology of the integration of a scramjet with non-rectangular section and a waverider airframe.Firstly,a software for the conceptual design and analysis was developed for quick design and evaluation of the X-43A alike vehicle,which included a parametric design program of the X-43A alike vehicle configuration,an automatic CAD program using UG API and an estimation program of aerodynamic force and heat.In addition,a series of programs,i.e.,two kinds of waveriders based on accurate and proximate cone derived methods,Busemann inlet and stream function analysis,were developed for the integrated design and analysis of the new type hypersonic vehicle.Secondly,a CFD program based on the cell-centered finite volume method was developed in this paper to solve the steady and unsteady problems of compressible calorically perfect gas.The traditional numerical technologies in the compressible computational aerodynamics,such as temporal integration algorithms,flux reconstruction,flux schemes,turbulence models,boundary treatments and the MPI parallel acceleration were included in the CFD program.Moreover,the flux schemes of AUSM-family with the new pressure flux were adopted in it.The numerical results of the fore-step shown that the new AUSM-family schemes could significantly improve the resolution of numerical calculations.A series of benchmarks were performed and verified the reliability and accuracy of the developed CFD program.It is shown that the self-developed CFD program could be applied to the follow-up engineering numerical simulations.The design program of minimum length nozzle with two methods of conservation of mass and eliminating wave theory to determine the nozzle contour was developed in this paper based on irrotational method of characteristics to achieve two dimensional and axisymmetric nozzles with constant and variable specific heat.Nozzles designed from eliminating wave theory exhibited better uniformity of outflow field compared with those designed from conservation of mass.The axisymmetric nozzle with constant specific heat was chosen to be the base flowfield and the shape of nozzle entrance was considered to be circle in this paper.A series of inviscid and viscous three dimensional asymmetry nozzles with different departure distances were designed in the base flowfield using streamline extraction technology and empirical formula of boundary layer correction.The effects of departure distances on geometry,flowfield and performances of those nozzles were studied.A novel truncation way of three dimensional nozzles using truncation method of two dimensional nonlinear compression was proposed in this paper to solve the problem that the length of nozzle achieved from base flowfield with complete isentropic expansion was too long.The axisymmetric base flowfield was firstly nonlinearly compressed,and then calculated by inviscid CFD to extract streamlines.Finally the truncated nozzle was achieved by fitting those new streamlines.The contrastive analysis of the effects of two parameters of the truncation method on the geometry,flowfield and performances of truncated nozzles was conducted by numerical simulations.It is shown that the contour of all truncated nozzles successfully avoided the problem of non-smooth.All truncated nozzles basically met the requirement of design length.The installed thrust coefficients of all truncated nozzles were higher than 0.93.The coefficients were even higher than 1.0 for the certain parameters of the truncation method.Furthermore,the three dimensional asymmetric truncated nozzle with circle shape of entrance and square shape of exit was designed using the streamline fusion technology and then compared to the truncated nozzle with circle shapes of entrance and exit at the same design conditions on geometry and performances.The design methodology of geometry integration was proposed in this paper,e.g.,the integration of the inward turning inlet and waverider.The essence of the methodology mentioned above was to carry out geometry operations on the shock wave surface,where the waverider airframe was on in the external flowfield,and the surface(shock/Mach wave or circle cone)where the entrance of inward turning inlet was on.The integrated configuration required that the entrance shape of the inlet had overlap with the leading edge of the waverider and meanwhile was exact on the lower surface of the waverider.The geometric integrated configuration was designed with truncated Busemann inlet and waverder based on proximate cone derived mehtod according to the design methodology of geometry integration.The comparison and analyses between the geometric integrated configuration and the original individual on flowfield and performances was implemented in this paper.The research shown that the classic design methods of the inward turning inlet and waverider could be adopted using the design methodology of geometry integration proposed in this paper;the integrated waverider was still riding shock wave without the effect from the integrated inlet and the liftdrag ratio was slightly higher compared to the original waverider;there was inflow capture loss at the position of the integrated inlet lip.But the mass capture was still increased by 7.4%.The exit pressure and outflow non-uniformity of the integrated inlet were improved to be 1.7 times and descended by 12%compared to the original inlet,respectively.However,the exit total pressure of the integrated inlet decrease because that the free stream compressed by the integrated waverider lost a part of total pressure and meanwhile the nonuniform inflow of the integrated inlet caused by the high pressure air from the lower surface of the waverider laterally flowing intensified the loss of total pressure.The inlet/outlet area ratios and flow parameters of scramjet parts and the performances of a scramjet which was composed with a truncated Busemann inlet with entrance of irregular shape and circular exit,a constant-area isolator with circle section,a circle section combustor and an axisymmetric nozzle was obtained based on stream function analysis.The airframe/propulsion integration was realized using the geometric integrated design method proposed in this paper,and then two vehicle configurations,i.e.,waverider and liftbody were obtained.The flowfield and aerodynamic performances of two vehicles were analyzed at constant dynamic conditions using the self-developed CFD program.This study suggested that waverider had significant effect of riding wave compared with the liftbody seen from the viscous flowfield at design point.However,there was heavy flow loss on the leading edge of waverider owing to the viscosity;the flowfields of the same parts of waverider and liftbody were almost consistent.All these indicate that the working states of their engines were also consistent;the lift-drag ratio of waverider remained over 1.8 at all conditions,even at poor conditions like low mach number and negative angle of attack of freestream.The lift-drag ratio of waverider exceeded 2.4 at the cruise condition;the lift-drag ratio of liftbody was higher than 1.0 at all conditions except negative angles of attack of free stream,nearly 1.8 maximum,and higher than 1.5 at the cruise condition;the drag of liftbody decreased more than half compared to waverider at the same conditions,which was conducive to achieving the balance of thrust and drag.