Numerical investigation of the labyrinth leakage flow on the performance of a compressor cascade

This paper examines the effect of labyrinth seal structure on the evolution of vortex systems and the performance of the cascade. It is found that the labyrinth seal leakage leads to the circumferential development of the separation vortex, and the axial influence region of the concentrated shedding vortex also expands, which increases the flow loss and reduces the diffuser capacity. Among all the cases, the deteriorating effect of the cavity without a labyrinth seal is the most significant. This results in an 83% increase in total pressure loss compared to the prototype cascade. The straight tooth labyrinth and the straight tooth labyrinth with block structures can effectively reduce the leakage from the sealing cavity and weaken the deterioration caused by labyrinth seal leakage. Among these schemes, the straight tooth with block scheme has the most considerable effect, resulting in a 19% reduction in total pressure loss. As the incidence angle increases, the recirculation zone on the end wall of each scheme gradually shrinks toward the leading edge. Meanwhile, the static pressure rises, and the velocity decreases near the leading edge. Compared with the straight tooth scheme, the straight tooth with block scheme can reduce the high-loss zone by 14% at most. In addition, as the sealing clearance gradually increases, the inhibitory effect of the straight tooth with block scheme on the deterioration of cascade performance caused by the labyrinth sealing cavity is gradually enhanced compared to the straight tooth structure. The improvement effect is optimal under 0.5 mm sealing clearance.