Effect of blade surface cooling on a micro transonic axial compressor performance at low Reynolds number

Abstract

Due to the high ratio of surface area to volume and the limitations of manufacturing precision, the impact of wall temperature and heat transfer on the aerodynamic performance of micro gas turbines is greater than that of traditional larger counterparts. Therefore, this study numerically investigates the effect of rotor wall cooling on the aerodynamic and thermal performance of a 1.5-stage transonic compressor at a low Reynolds number using a three-dimensional Reynolds averaged Navier-stokes (RANS) simulation.In this study, we use a volume model that takes into account the actual shaft work, and the main findings can be summarized as follows: At the optimal wall temperature, wall cooling could potentially raise the compressor performance, with the peak efficiency increasing by about 3.7% and the pressure ratio increasing by about 1.8%. Wall cooling reduces the dynamic viscosity and increases the wall shear stress, which delays the laminar separation transition process, promotes the reattachment, and shortens the laminar separation bubble, substantially decreasing separation losses. Meanwhile, the loss caused by vortex dissipation decreases. Wall cooling slightly improves the matching relationship between the rotor and the aft stator, and also reduces the flow separation losses of the stator. Wall cooling introduces additional thermal and viscous dissipation to the blade passages, which prevents the compressor’s aerodynamic performance from increasing continuously. The present study analyzes the separation transition process, the entropy production mechanism, and deeply explores the effect of wall cooling, which is meaningful for the aerodynamic and thermal design of advanced micro-compressors.