A study of partial admission characteristics on a small-scale radial-inflow turbine

Abstract

When a turbine is operated at a low partial admission rate, its performance can show wide deviation from the predicted results depending on the operating conditions and geometric parameters. In order to investigate the performance characteristics on a partially admitted turbine based on the geometric parameters, a turbine was tested with various tip clearances and nozzle flow angles. In addition, the effects of the partial admission rates were studied, and the turbine output power on each stage was measured to investigate the effects of the mainstream diffusion along the turbine stage by partial admission. The outer diameter of the turbine rotor was 108 mm, and its partial admission rate was 1.4-4.1 per cent. The tested turbine was designed as a radial-type turbine that had a circular plate disc for rotor rows. The rotor and the stator were designed as a typical axial-type blade, and the turbine consisted of three stages. The turbine performance was obtained in a wide rotational speed range in order to compare its performance according to various operating conditions. The net specific output torque was also measured to compare its overall performance. Computational analysis was conducted for predicting turbine performance. The computed results were in good agreement with the experimental results.