带双凹槽燃烧室中超声速流场的数值模拟

针对新近提出的双凹槽和预燃室结构的燃烧室概念,采用混合通量分离法及NND格式,对其中的冷态流场进行了数值模拟.结果表明:在没有喷流条件下,该结构是典型的开式流动,有利于混合,在工程应用范围内,可以用二维结果粗略地估算三维情况;但在有喷情况下,开式结构被打破,必须对三维流动作真实模拟.

Numerical Simulation of Supersonic Flow in Combustor with Dual-Cavity

As we all known, among the components of scramjet, combustion chamber plays an important role, the performance of which is crucial for the success of engine design. The factors that can influence the combustion capability include fuel mixture, combustion and entropy increase. Combustion efficiency is an important factor evaluating the performance of combustion chamber and is mainly effected by the mixing of fuel and air and the flame stability. In the chamber, the resident time of the mixture is very short, and the shear layer is more steady because of the compress influence at high Reynolds number. As a result, the mixing efficiency is lower than that under subsonic condition. One way of overcoming the defects is increasing the length of the chamber, but the capability is limited because the size of engine is very small. Compared with traditional concept, a novel concept called dual-cavity with pre-burner, which is proposed by Prof. Situ. is presented in this paper, and the characteristic and mechanism of flows in this dual-cavity are studied. With the NND scheme and hybrid flux splitting technique, some numerical simulations are carried out for supersonic flows in dual-cavity with pre-burner. The complex flow phenomena, such as the interaction between shock wave and viscous, shear layer and separation, are captured successfully. The obtained results also show that the flow pattern for no injection case is a typical open type, and this is beneficial to flow mixing, but the open type structure is broken when the injection is active. For no injection case the results obtained by using 2-D code instead of by using 3-D code can be used for engineering design, and this is very useful and economical for engineering problem. But three-dimensional flows should be simulated for the case with injection.