Application of shear-sensitive liquid crystal coating on flow visualization of compressor cascade

摘要

Many of the recent advances in the design of high performance compressor were possible attribute to better understanding of the influence from the boundary layers. Shear-sensitive liquid crystal coating (SSLCC) has been regarded as a promising technique owning to its unique advantages of non-intrusive, high resolution, and high sensitivity. In this paper, SSLCC technology is introduced to compressor cascade measurement for the first time. Measuring system using SSLCC in internal flow is designed and established. Massive experiments, conducted at continuous high subsonic cascade wind tunnel, are carried out to measure the transition position. Quantitative and qualitative data analysis approaches are described in detail. Based on images analysis, complex flow phenomenon including flow separation, reattachment and transition are captured successfully, and the effect of Mach number and angle of attack on the boundary layer flow are also analysed. The results show that: 1) the Mach number has a significant effect on transition position, and the transition line shifts backward with the increase of the Mach number; the transition line disappeared after the Mach number researches to a certain value; 2) the angle of attack has little effect on transition position, but it has a great impact on the transition distance; 3) influenced by the end-walls, the reattachment phenomenon occurs in advance.