Study on Rocket-Based Combined-Cycle Engines

近年来，基于火箭的联合循环(RBCC)发动机因其具有更高的有效载荷起飞重量比和更高的比冲等吸引人的特性而受到越来越多的关注。本研究选取超燃冲压发动机作为RBCC系统的跨大气层加速模式，研究了LASE模式和超燃冲压发动机模式与RBCC系统相结合的可行性。在波纹直翅式换热器研究的基础上，进行了液氢冷却换热器的实验研究，验证了一种估算空气液化率α的方法。结果表明，α的测量结果与用这种方法得到的计算结果吻合得很好。基于这种估计α的方法，利用热传递…的参数，得到了α与飞行马赫数M之间的关系换热器面积较大，以评价LASE系统的基本模型的系统性能。结果表明，在飞行马赫数M=1~5的情况下，将供氢线从花边1改为花边2是获得高比冲的最合理方法之一。利用超音速风洞对进气模型进行了实验，验证了由N-S方程得到的数值结果。结果表明，该计算方法具有足够的精度来评价超音速进气道的定性性能。在此基础上，研究了两种进气模型的特性，并在准一维流动假设下计算了机身一体化对超燃冲压发动机性能的影响。研究了三种不同类型的机身一体化。结果表明，发动机与机身轴线平行地集成在机身上，并有一个吸入机头冲击波压缩空气的进气口是可取的。研究了矩形阶梯超燃冲压发动机隔振器中的伪激波，当伪激波的前沿到达阶跃时，第一次激波的压力发生振动，其清晰的频率峰值为320-480 Hz。然后，伪激波在台阶上游进一步传播，第一次激波周围的压力以100-200赫兹的频率振动。结果表明，带台阶的矩形通道中的这些特征是由台阶下游的回流引起的。较少

Recently, rocket-based combined-cycle (RBCC) engines have been discussed more frequently because of their attractive characteristics, such as an increased payload-to-take-off-weight ratio and a higher specific impulse. In this study the ScramLACE (liquefied air cycle / supersonic-combustion ramjet) engine was chosen for the transatmospheric accelerating mode of the RBCC system to investigate the feasibility of using the LACE mode and the Scramjet mode combination with the RBCC system.An experimental study on cooling the heat exchanger by liquid hydrogen was conducted to validate a method of estimating the air liquefaction ratio, alpha, based on the study of corrugated-straight-fin heat exchangers. The results showed that the measurements of alpha are well coincident with the calculations obtained by this method of estimating alpha. Based on this method of estimating alpha, the relationship between alpha and the flight Mach number, M, was obtained using a parameter of the heat transfer … More area of the heat exchanger in order to evaluate the system performance of a basic model of the LASE system. From the results, it was clarified that changing a hydrogen supply line from LACE 1 to LACE 2 at a selected value of the flight Mach number is one of the most reasonable ways to achieve a high specific impulse during the LACE mode operation, M=1 to 5.An experiment of an air intake model during the LACE mode operation was performed using a supersonic wind tunnel to validate numerical results obtained from Navier-Stokes equations. It was found that this computational method has sufficient accuracy to evaluate the qualitative performance of the supersonic intake. Based on this method, characteristics of two types of the intake model were investigated.Effect of airframe integration on scramjet performance were calculated on the assumption of quasi-one-dimensional flow. Three different types of airframe integration were investigated. From the results, it was clarified that it is desirable for the engine to be integrated on the airframe paralleled to the airframe axis, as well as to have an inlet inhaling the air compressed by the shock wave from the nose of the airframe.The pseudo-shock waves in rectangular scramjet isolators with steps were investigated, When the front of the pseudo-shock waves first reached to the step, pressure at the first shock vibrated with the clear frequency peak of 320-480 Hz. Then the pseudo-shock waves propagated further upstream of the step, the pressure around the first shock vibrated with 100-200 Hz. From these results, it was found that these features in the rectangular duct with the step were caused by the recirculation right downstream of the step. Less