Numerical study of the tip clearance flow in miniature gas turbine compressors

Miniature gas turbines struggle to obtain the efficiencies of the larger counterparts. One of the issues is the larger tip clearance in the compressor due to manufacturing tolerances. In this study, we have performed two numerical parametric studies to determine the influence of tip clearance on gas turbine compressors in the miniaturization process. Firstly, varied tip clearance values are applied when a constant Reynolds number is maintained to investigate the effect of tip clearance value on compressor performance. Thereafter, varied Reynolds numbers are applied when a fixed tip clearance value is used to investigate the effect of miniaturization on compressor performance. Our results quantify the compressor performance deterioration with the existence of tip clearance and show the performance loss amplifies with the increase of tip clearance value as well as with the miniaturization of the compressor. The flow field near the blade tip region has been studied in detail to identify the occurrence of fluid jet and the transition of fluid jet when tip clearance is applied. This study demonstrates the significant impact of tip clearance on compressor performance and quantitatively shows the effect of miniaturization on compressor performance when blade tip clearance exists.