Research On Blending Combustion And Influence Law Of Solid Rocket Super-burning Ramjet Engine

Solid-rocket scramjet has many advantages compared with other scramjets,such as there is without ignition and flame stabilization difficulties,the flow is easily regulated,structure is simple,operational reaction time is short,and so on.Therefore,the solid-rocket scramjet has high application value in hypersonic weapon system.As the supersonic mixing combustion place,the second combustor directly affects the engine performance.Therefore,it is significant to study the supersonic mixing combustion and influence of the second combustor of solid-rocket scramjet.The supersonic mixing combustion process in the second combustor is studied by means of numerical simulation.A physic and mathematic model and calculation method are established to describe the supersonic mixing combustion process in the second combustor.SST k-? model and turbine dissipation model are applied to be as turbulence model and turbulence combustion model,respectively.The established model and calculation method are applied to simulate the supersonic diffusion combustion test of Evans and the experiment of solid-rocket scramjet of the fourth academy of the CASC,which verify the accuracy and rationality of the established model and calculation method.The influence of the structure factors change on the second combustor performance is studied by conbining with orthogonal experimental design.The calculation result suggest that:(I)The combustion efficiency increase with the increase of combustor length at all levels,while decrease with the increase of combustor expansion angle at all levels.The influence of combustor length and expansion angle on the combustion efficiency is highly significant.(II)The total pressure recovery coefficient increase with the decrease of combustor length at all levels,while increase with the increase of expansion angle of primary combustor.Except for the second and three stage combustor,other structure parameters significantly influence the total pressure recovery coefficient.The influence of the structure parameter of primary combustor on the combustion efficiency and total pressure recovery coefficient is the largest.(III)There is a choking phenomenon when the length and expansion angle of primary combustor are too long and too short,respectively.In addition,the influence of the inlet air parameter change on the second combustor performance is studyed.The research indicate that:(I)The static pressure,chemical reaction rate,combustion efficiency,total pressure recovery coefficient,trust,and specific impulse in second combustor increase,while the average Mach number and shock wave intensity decrease with the increase of air-fuel ratio and inlet air total temperature.(II)The static pressure,chemical reaction rate,combustion efficiency,total pressure recovery coefficient,trust,and specific impulse in second combustor decrease,while the average Mach number and shock wave intensity increase with the increase of inlet air total pressure.Furthermore,the sensitivity of inlet air parameters is anylized and the result indicate that the influence of air-fuel ratio on the second combustor performance is the largest.The influence of injector surface,injector number,and gas spray angle on the second combustor performance is further analyzed.The research suggest that the combustion performance of the second combustor with oval injector is apparently better than that of second combustor with circular injector.The combustion efficiency,trust,and specific impulse increase,while the total pressure recovery coefficient decrease with the increase of major semi-axis of oval injector.The combustion efficiency,trust,and specific impulse increase first and then decrease with the increase of injector number.The combustion efficiency,trust,and specific impulse increase,while the total pressure recovery coefficient decrease with the increase of gas injection angle.The optimal design of fuel-rich gas injector is an effective method to enhance the mixing combustion.