The Influence Of Blade Parameters Changes On Profile Loss And Corner Separation

The development level of aero-engine has become an important indicator to measure a country's military level and comprehensive national strength. Modern aero-engine developed towards high thrust-ratio has put a further demand on compressor, required it has a high load, high efficiency, high stability characteristics. Search a good compressor blade with a great aerodynamic performance is a major route to improve the aerodynamic performance of compressor.In this paper, the main content is the flow characteristics boundary layer of compressor cascade. First studied the influence of the blade parameter changes on cascade loss, and gives a new method to describe the cascade loss, use the entropy generate of boundary layer to describe cascade loss. Second use the basic theory of three-dimensional separated flow, studied the influence of suction surface corner separation on the flow characteristics. In the end studied the influence of the blade parameter changes on suction surface corner separation in rectangular cascade.In subsonic flows, cascade loss mainly includes blade boundary layer loss and wake mixing loss. This paper study four blade profiles, the results show that, blade surface boundary layer losses mainly concentrated in the front, more than 50 percent of total entropy is generate in less than 30 percent of the chord wise length; it was found that the suction surface tends to generate more entropy than pressure surface, about 75 percent of total entropy is generate on suction surface; at the same chord wise location, the greater the curvature of blade profile the greater the local entropy generation rate of boundary layer; the majority of entropy generation occurs near the blade trailing edge in the wake, more than 80 percent of total entropy is generate in less than 20 percent of the chord wise length after trailing edge in the wake, after 50 percent of the chord wise length the entropy generation is very small.This paper study NACA-65 and CDA profile type of rectangular cascade, in the condition of the same chord length, stagger angle, pitch, inlet and outlet blade angle different profile produced different forms of corner separation, the result show that the suction surface corner separation in NACA type cascade was an open separation, and in CDA type cascade was a closed separation. The diffusion confusion capability in closed separation was significantly lower than in open separation on the separation zone, and loss was higher than the open separation.The change of profile parameter has great influence on the corner separation, not only affect the range of separation zone, also will change the separation type. This study show that with the increase in the thickness of blade profile, the maximum thickness location moves afterwards and the increase of the deflection of mean camber line the flow wise adverse pressure gradient on the suction surface after the lowest pressure point increased, not only increased the range of separation zone, also the separation type change to closed separation from open separation.