Loss Characteristics of Cantilevered Cascade With Moving Endwall Under Upstream Wake Influence

Abstract

Abstract. In multistage small-core compressors, the inflow conditions of cantilevered cascades exhibit considerable complexity. It is characterized by a larger ratio of tip clearance size to chord length and a larger ratio of wake width to pitch. These factors make it challenging to clarify the key influence of upstream wakes on large-clearance leakage flows within multistage environments. To take this challenge, this article incorporates realistic wake inflow and endwall rotation boundary conditions into the cascade simulations. Based on the wake observations of the multistage compressor (SJTU-LSRC), two sizes of cylinders were designed and positioned upstream of the controlled diffusion airfoil cascade to generate two distinct types of inflow wakes. One wake width is comparable to the multistage compressor wake width, and the other with an expanded width. By employing an unsteady numerical simulation method, the interaction between wake and cantilever cascade clearance leakage is decoupled and elucidated. The effects of different wakes on cascade losses and secondary flows were examined, including tip leakage flow evolution, mid-span flow mixing, and hub suction-side separation changes. Results show both wake widths stabilize clearance leakage flows. However, the wider wake induces significant mid-span mixing losses, increasing cascade entropy loss coefficients by 68% (large clearance) and 94% (small clearance) compared to the narrow wake. This study provides critical insights into small-core compressor flow mechanisms, aiding performance optimization and research advancement.