Effect of tip injection on performance of high-load helium compressor cascade in high temperature gas-cooled reactor

Abstract

The helium compressor's high-load design approach causes more significant tip-leakage and secondary flow in the passage. Tip injection can effectively restrain the growth of leakage vortex and improve the diffuser capacity of the cascade. In this paper, numerical simulation and wind tunnel experiment are employed to investigate the impact of tip injection on cascade aerodynamic performance in two aspects: axial deflection angles and pitch angles. Under the optimal combination of the injection angle, the effect of tip injection on the cascade performance at different relative positions of guide-rotor blades is investigated. The numerical results demonstrate that an appropriate axial deflection angle enables the leakage vortex with the high-energy fluid to fade on the pressure surface of the adjacent blade, thereby weakening its impact on the downstream flow field. A suitable pitch angle diminishes the strength of the passage vortex formed at the guide vane's trailing edge, which minimizes its mixing with the tip leakage vortex and leakage flow. The injected high-energy flow facilitates the dissipation of the vortex system. The experimental results indicate that tip injection has positive effects on different relative positions of guide-rotor blades, and Case-4 has the most significant improvement effect, with a loss rate of 8.22%.