Off-Design Performance of a Linear Cascade of Turbine Blades

Abstract

A recent survey of the literature showed a clear need for additional experimental results on the off-design performance of turbines, particularly for airfoils of recent design. This study presents measurements of the low-speed two-dimensional performance of a linear cascade of turbine blades with a turning angle of 87 degrees. The incidence was varied between −25 and +25 degrees in 5 degree steps. The blade surface pressures, total pressure loss coefficients and trailing-edge deviations are presented for all values of incidence. The influence of incidence on the critical Reynolds number is also examined. Surface flow visualization is presented for different values of Reynolds number and incidence to aid in the physical interpretation of the measurements. The measured total pressure losses agree very well with the new off-design correlation introduced by Moustapha et al. (1989).