Performance Test of Centrifugal Compressor for Microturbine with Running Tip Clearance

운전 익단간극을 고려한 마이크로터빈 코어용 원심압축기의 성능특성 연구

Tip clearance of centrifugal compressor affects the performance. Larger tip clearance results in lower efficiency. What really affects the performance is the running tip clearance, not the cold tip clearance. When the compressor is operating, blade strain and the pressure difference between impeller backplate and hub affects the running tip clearance. This paper describes measured running tip clearance and its effects on the performance of centrifugal compressor. Cold tip clearance before operation was 0.4 mm and running tip clearance varied from 0.86 mm to 0.25 mm with impeller exit pressure. As the pressure at impeller exit increases, the routing tip clearance tends to decreases. The target running tip clearance for compressor at $100\%$ speed was 0.3 mm and it turned out to be exactly 0.30 mm from experiment.