Researches on the Two-Dimensional Retarded Cascade : Part 3, Cascade Performances at High Inlet Angles

Abstract

Two-dimensional cascade date at inlet angles higher than 65° have been presented which are required often for the designs of axial blowers. Cascade tests of NACA 65-series compressor blades were performed by the testing technique which had been established by the authors in the foregoing paper. Reliable data have been obtained in the ranges of inlet angle β1 =65∼80°, solidity σ=0.5∼1.33 and camber Cl0 =0.0∼2.0. In the result, characteristics of cascade performance at high inlet angles are found. In the case of high inlet angles, it is necessary to take care in selecting a design angle of attack, because the range of angles of attack for effective operating region is very narrow. Limited blade loadings at high inlet angles are smaller than those at low inlet angles. Investigating various blade loading factors, defined by some researchers, Lieblein's equivalent diffusion ratio has been modified to apply also to cascades at high inlet angles. Some available data about the minimum loss coefficients and the blade efficiencies have been presented.