Compressor Cascade Optimization based on Inverse Boundary Layer Method and Inverse Cascade Method : 2nd Report, An Inverse Boundary Layer Method and Wind-Tunnel Tests of Optimized Compressor Cascade with High Loading

An aerodynamic approach to an optimum compressor cascade in a two-dimensional incompressible flow is described on the basis of two inverse problems ; namely, an inverse boundary layer problem in order to produce the optimum surface velocity distribution and an inverse cascade problem in order to obtain the blade section which realizes a prescribed velocity distribution. A new method for the former problem is developed in this paper; namely, the momentum equation is integrated for a prescribed shape factor distribution in order to get an unseparated turbulent flow approaching the equilibrium state. An inverse cascade design method is introduced by combining the thus obtained optimum surface velocity distribution with the inverse cascade method proposed in the previous report. Highly loaded compressor cascade designed by this method was tested in a low speed cascade wind-tunnel. Reasonable agreement between the theory and the experiments is obtained and the maximum lift-drag ratio is about 1.4 times as high as that of corresponding NACA 65 series cascade at design operation.