一种考虑壁面摩擦作用的发射井引射器设计方法

A Method for Design of Silo Ejector Concerning with Wall Friction

针对发射井优化设计问题,基于引射器函数方法提出了一种考虑壁面摩擦作用的发射井引射器准一维设计方法,建立了考虑壁面摩擦作用的引射器函数和静压协调函数.证明了考虑壁面摩擦作用时驻点速度小于声速,引射器不能达到第三极限,只能达到驻点极限.以实际算例分析了发动机总压、发射井横截面积、混合室出口压强变化时的引射器工作特性,画出了工作特性曲线.采用计算流体力学(computational fluid dynamics,CFD)方法,分别建模分析了发动机总压、发射井横截面积、混合室出口压强变化时发射井引射器中超声速射流流动形态,将CFD方法得到的混合室入口压强与准一维方法的结果进行了对比.结果表明,准一维方法得到的工作特性曲线与CFD方法的计算结果差距较小,在混合室背压变化时最大误差为4.31%,验证了准一维方法的准确性.

Aiming at the problem of silo design,a quasi-one dimensional method concerning with wall friction was proposed based on the ejector function method.A mathematical model of wall friction was proposed and ejector functions and static pressure matching functions concerning with wall friction were established.The analysis results prove that the velocity at the stagnation critical point is less than sonic speed,the stagnation critical point of ejector can be achieved and the third critical point is impossible to achieve.And then,the characteristics were analyzed with practical examples,considering the engine total pressure,the cross-sectional area of the silo and the outlet pressure of the mixing chamber changed respectively,and the characteristic curves were drawn.The flow patterns of supersonic jet ejectors were analyzed by CFD method,considering respectively the engine total pressure,the cross-sectional area of the silo and the outlet pressure of the mixing chamber changed.At the same time,the inlet pressures of ejectors obtained by CFD were compared with that obtained by the quasi-one dimensional method.The results show that the errors between the CFD method and the quasi-one dimensional method are little on characteristic curves and their largest value is 4.31%when the backpressure changes,which verified the quasi-one dimensional method.