Optimization design of seal cavities for shrouded stators

In this study, to reduce the negative impacts of cavity leakage flow on the aerodynamic performance of a shrouded stator, the structure of the seal cavity is optimized. First, the cavity structure is parameterized, and under different cavity design schemes, annular cascades with a cavity structure are simulated numerically to construct a sample database. On this basis, a neural network and genetic algorithm are used to establish the relationship between the modeling parameters and performances to find an optimal solution. Finally, the mechanism whereby the optimized cavity improves the compressor performance is analyzed. The results show that the optimized seal cavity reduces the leakage flow by approximately 30%, while the windage heating through the cavity remains unchanged. Also, the circumferential velocity of the leakage flow at the outlet of the cavity increases, so its ability to resist the boundary layer and pressure gradient extrusion is enhanced in the cascade passage. These two improvements reduce the influence area of the cavity leakage vortex and delay the passage vortex, which can decrease the momentum loss thickness of the boundary layer and reduce the total pressure loss coefficient of the cascade by 2.14%. Furthermore, the changes in the optimized cavity structure exhibit a high degree of consistency with the trends of the correlation analysis. Therefore, according to the structural characteristics and control mechanism of the seal cavity, the proposed optimization method can obtain remarkably effective cavity structures, taking into account the cascade loss minimization as well as the security stability of the inter-stage sealing.