Analysis On The Structural Parameters Of An Asymmetric Ramp Vortex Generator In Supersonic Flow

Compressor is one of the core component of aero engines. Its efficiency and boosting capacity has an important impact on the key performance indicators of the engine such as thrust-weight ratio and efficiency. Currently, the development of transonic axial compressor which stage load increased year by year has matured. It is of great significance to pay attention to study the work of the supersonic compressor in order to get higher thrust-weight ratio.There is complicated flow structure in supersonic compressor. At present, it is difficult to reduce the losses caused by shock/boundary layer interaction which have a serious impact on the efficiency of supersonic compressor. For reducing the shock loss when pressure rises across shock, in recent half a century, researchers carried a large amount of research on the shock wave structures and proposed many models to predict the shock loss using CFD software with the rapid development of computer technology in order to design suitable shock wave structure. Moreover, a series of methods about controlling the effect of shock/boundary layer interaction were put forward such as boundary layer bleed, boundary layer suction, plasma control, vortex generator control and so on. As one kind of passive control devices, micro-vortex generator has many advantages as well as traditional vortex generators. For example, its structure is simple and additional gas flow is not required. As a result, they can’t produce too much extra loss. Besides, micro-vortex generator has small shape resistance and nearly can’t affect the main flow field because of its small size. Therefore, it is considered as one kind of passive control devices with good prospect in application. A numerical simulation about how an asymmetric ramp vortex generator affect the supersonic flow field was carried out in this paper. And its structural parameters were optimized in order to have more excellent controlling performance on shock/boundary layer interaction. The main work in the thesis is listed as follows:(1) The reliability of numerical methods used in this paper were validated with the test result of a micro-ramp vortex generator. The comparison with experimental results indicates that the numerical method have good accuracy in predicting the flow feature affected by the micro-vortex generator in supersonic flow and the distribution of velocity in boundary layer. In conclusion, the numerical method is capable of meeting the needs of supersonic flow simulation in this paper.(2) Based on the orthogonal test design, the controlling performance of an asymmetric micro-ramp vortex generator on shock/boundary layer interaction in supersonic flow was analyzed and its height(h)、length(L) and width(w) were optimized. Also, the reasonable value range of interval(S) between vortex generators and distance(R) from vortex generator to the position of shock/boundary layer interaction was confirmed. The research results show that good controlling performance on shock/boundary layer interaction will be got when a series of optimal scaling parameters, h/S=0.4、S/h=5.5-7.5, w/L=0.51, w/S=0.6-0.82, R=15h～25h, are selected.(3) The flow feature of a supersonic cascade(SL19) was analyzed. Using a series of optimal scaling parameters got in prior studies, a vortex generator was designed and used in the supersonic cascade to examine its controlling performance on shock/boundary layer interaction in suction surface. The study shows that the position of shock/boundary layer interaction moves forward and the pressure curve flattens out under the control of vortex generator. The distribution of velocity in boundary layer behind the position of shock/boundary layer interaction is improved. Although the boundary layer thickness increases, the incompressible shape factor decreases which indicates that it is helpful to inhibit the boundary layer separation.