New Correlations of the Two-Dimensional Turbine Cascade Aerodynamic Performance

Abstract

Theoretical evaluation and experimental research have been conducted to verify the performance of steam and gas turbines, including exhaust turbines of superchargers. The simplified channel method and hydroelectrical analog method have been used to calculate blade surface velocity distribution. Based on the “fully developed turbulence” assumption, viscous effects are approximately taken into account by using the boundary layer theory. Theoretical optimum profile loss coefficients are given. Effects of velocity profile on losses are analyzed. Turbine cascades have the characteristics of high solidity, high setting angle, and high air turning angle, which facilitate the use of the channel concept. On this basis, K. W. Todd’s “passage convergent gradient,” modified O. Zweifel’s “tangential load coefficient” and other effective criteria have been chosen and cascade data correlated. Some relatively accurate semiempirical formulas for predicting the aerodynamic performance of cascades are formulated.