离心叶轮叶片前缘椭圆长短轴比对性能的影响

Effects of Axial Ratio of Ellipse of Blade Leading Edge on Performance of a Centrifugal Impeller

关键词:  离心叶轮  数值模拟  椭圆长短轴比  实验验证  静力分析

Key words:  Centrifugal impeller  Numerical simulations  Axial ratio of ellipse  Experimental verification  Static analysis

摘要:

使用数值研究方法研究了三个机器马赫数(Mu)下，小尺寸离心叶轮叶片前缘采用长短轴比例分别为1:1，2:1，3:1，4:1的椭圆形(圆形前缘可认为长短轴比为1:1)时叶片前缘附近流场情况及不同前缘形状对压缩机气动性能的影响(Mu主要应用于工程中，在离心压缩机中是用来衡量叶轮转速的一个无量纲量)。结果表明，椭圆形前缘随着长短轴比例的增大，可有效减小叶轮入口处的分离损失，使压缩机性能明显提高，喘振裕度及工作范围没有明显变化，并对结果进行了实验验证。经过静力分析，叶片前缘椭圆形长短轴比例的增加对叶轮强度影响不大。在小尺寸叶轮的设计和加工中，如压缩机在正常叶轮入口机器马赫数下运行(Mu=0.95附近)，叶轮叶片前缘椭圆形长短轴比例对压缩机性能略有影响，可折衷考虑加工效率和压缩机性能；如压缩机在叶轮入口机器马赫数较高工况下运行较多(Mu大于1)，叶轮叶片前缘椭圆形长短轴比例对压缩机性能影响较为显著，可将比例选为3:1或4:1。

Abstract:

The flow field near the elliptical blade leading edge of small-sized centrifugal impeller which respectively applied 1:1，2:1，3:1，4:1 as the axial ratio of ellipse and the effects of different leading edge shapes on aerodynamic performance of compressors were studied under three Mach number (Mu) by numerical simulations. The leading edge is circular when the axial ratio of the ellipse is 1:1. Mu is mainly applied in engineering project. It is a dimensionless quantity used to measure the rotating speed of the impeller in the field of compressor. The contrastive analysis results，which were obtained from a series of numerical simulations，show that separation loss near the inlet would be reduced with the rise of the axial ratio of elliptical blade leading edge，and performance of compressor was also significantly improved. At the same time，the surge margin and the range of working conditions did not show a clear change. Then the results were validated by performance experiments. The rise of the axial ratio of ellipse of blade leading edge had little impact on impeller strength through static analysis. During the manufacturing and designing process，if the compressor always is operated near Mu of 0.95，the effects of different axial ratios of ellipse of the leading edge on aerodynamic performance of compressors are little，and the tradeoff between the processing efficiency as well as the performance of the compressor could be made. If the compressor is always operated under Mu of 1 or bigger，the effects are obvious and the axial ratio should be 3:1 or 4:1.