Effects of the Blade Tip Loading Distribution on Transonic Centrifugal Impeller Stability

Blade loading distribution is a crucial parameter for a compressor design. This study investigates the impact of the blade tip loading on transonic centrifugal impeller stability, comparing front-loaded and rear-loaded impeller designs through full annulus URANS simulations. Key findings reveal that the overall stability of the compressor relies on the interaction between inducer and exducer behaviors. The front-loaded design strategically shifts the inducer’s instability point to a higher volume flow rate where the exducer is more stable. It helps enhance the overall impeller stability but at the cost of efficiency. This is because different blade loading designs influence workload distribution within the inducer and exducer. The front-loaded design imposes higher inducer loading with early work input rollover and increased losses. This design better shapes its pressure-rise characteristics and extends stability, albeit with efficiency trade-offs. Detailed flow analysis shows that the front-loaded design intensifies tip-leakage flow, accelerating interactions and leading to earlier leading edge flow spillover. In contrast, the rear-loaded design displays a more stable tip-leakage flow, delaying the spillover and inducing early overall pressure-rise drop when the exducer’s stability is weakened. However, both designs converge in flow fields and performance characteristics when significant reverse tip flow occurs at low flow conditions.