Investigation of the Aerodynamic Performance of Small Axial Turbines

Abstract

This paper describes results of an experimental investigation of small axial turbine performance characteristics. Included are test data on the effects of the following design variables on small turbine aerodynamic efficiency: (a) blade height, (b) vane endwall contouring, (c) blade reaction, (d) blade tip clearance, (e) stage work, and (f) vane and blade airfoil row solidity. In addition, the effects of vane, blade, and disk cooling air injection on turbine efficiency are presented. The turbines evaluated were single stage, low aspect ratio configurations sized for airflows of 8 pps (3.63 kg/sec) or less and designed for inlet temperatures in the 2200-to-2500 deg F (1204-to-1371 deg C) range. The efficiency data presented in the paper cover both design and off-design velocity and pressure ratios. These data illustrate that relatively high efficiencies can be obtained in small, low aspect ratio axial turbines with an optimum design.