Trailing edge loss analysis of high-speed cryogenic microturbines used in helium applications

Abstract

The trailing edge flow characteristics have significant impact on the turbine performance. To improve the performance of the turbine, a detailed analysis of the turbine flow field and the loss generation mechanisms associated with trailing edge is called for. This is of much importance in cryogenic helium turbines as the flow characteristics would be different from other turbines due to its characteristics like higher speed and smaller dimensions. In this paper, the trailing edge loss mechanism and the effect of trailing edge profile on the performance of a cryogenic helium turbine was analysed using CFD. The effect of flow separation, base pressure and trailing edge blockage were analysed. The study observed that the trailing edge loss became significant only when its thickness was increased beyond 3% of the blade pitch. This will provide some leeway for the manufactures to have thicker trailing edges without compromising on the turbine performance.