跨声速压气机叶栅流动状态的试验和数值研究

For the unique incidence problem in the wind tunnel experiments of the transonic compressor cascade, by conducting experimental measurements and numerical simulations under different inflow Mach number and back pressure condition, this study elucidates the formation mechanism of the uniqueness in the inlet flow field of the cascade under the subsonic and supersonic inflow conditions, and analyzes the impact mechanism of the static pressure ratio on the cascade flow states and shock wave structures. The research results indicate that under low back pressure conditions, the shock wave within the transonic cascade exhibits a dual shock wave pattern, characterized by a leading edge detached shock wave and a passage normal shock wave.As the back pressure increases, the position of the passage shock wave gradually moves forward and eventually merges with the detached shock wave to form a single shock wave pattern. Under supersonic inflow conditions, the inlet flow field parameters arc influenced by shock wave-expansion wave systems and present a wave distribution. The measuring position of the inlet flow parameters should be at least 50% chord length distance from the leading edge of the cascade. Theoretical analysis reveals that the unique incidence phenomenon of the transonic cascade can be extended to high subsonic inflow conditions, but with different physical mechanisms. In supersonic states, the inlet airflow angle depends on the inflow Mach number and the geometric shape of the cascade inlet, whereas in subsonic states, the angle depends on the inflow Mach number and the throat area of the cascade. As the static pressure ratio increases, the transonic cascade operation undergoes the transition from a blocked state to a spilling state and eventually to a design state, with the total pressure loss coefficient decreasing monotonically from 0. 175 to 0. 082 at the incoming Mach number of 1. 10, with a decrease of more than 50%. The results of the cascade variable back pressure experiments indicated that the three-dimensional effects of the flow field were enhanced when the static pressure ratio exceeded 1. 379, which affected the periodicity of the cascade flow, and the cascade trailing edge throttle plate interfered with the measurement of wake parameters. These findings aid in comprehending the variations in the transonic compressor cascade's operation state, shock wave structure, and unique incidence flow field. They can also serve as guidance for transonic cascade experiments.