Experimental Study on Radial Turbine, with Special Reference to the Influence of the Number of Impeller Blades on Performance Characteristics

Abstract

Experiments were conducted to ascertain the influence of the number of impeller blades on the performance characteristics of a radial turbine. Thus, impellers fitted with 4, 8, 16, 24 and 32 blades respectively were employed, and the radial turbine was driven by compressed air delivered from Roots blowers. Besides usual measurements of pressures and temperatures, the flow directions as well as the magnitudes of the absolute velocities at the entrance of the impeller were observed by a yaw meter. The following results were obtained. (1) The optimum number of impeller blades of a radial turbine is not less than that of a radial compressor. (2) At regions of maximum overall adiabatic efficiencies, the relative velocities at the entrance of the impeller incline rotationwise by the angles 20∼30 degrees.