Aerodynamic Performance of Multi-stage Axial Compressor Considering Cold-to-Hot Deformation Effect

Abstract

Predicting the exact performance of multi-stage compressors for an aircraft gas turbine is important in the design process and calculation of off-design characteristics. This study explores the quantitative effects of cold-to-hot deformation on the aerodynamic performance of a three-stage axial compressor in terms of power consumption and efficiency. The reason of difference between numerical result and performance test data is investigated. Three-dimensional computational fluid dynamics (3D CFD) was used to predict the flow characteristics. A finite-element (FE) analysis was conducted to calculate the displacement caused by rotation, thermal expansion, and pressure force. First, the fluid domain of the compressor with cold geometry was analyzed via a 3D CFD analysis, and the displacement for all coordinates was then obtained from the FE analysis. The hot geometry and mesh for the fluid domain were generated based on the cold geometry and calculated displacement. Finally, the aerodynamic performance of the compressor with hot geometry was evaluated via a 3D CFD analysis. The results for the hot geometry compressor were more consistent with the performance test data than those for the cold geometry compressor in terms of the pressure ratio and efficiency based on the mass flow rate. Moreover, the average rotor tip clearance decreased by approximately 0.5% with respect to the span height by the cold-to-hot deformation. The total pressure loss at the rotor tip region was lower for the hot geometry compressor than the cold geometry compressor because of the reduced entropy of the high vortex loss core around the rotor tips. The results showed that the power consumption was 1.16% higher for the hot geometry compressor than the cold geometry compressor at the designed pressure ratio, which was primarily caused by an increase in the mass flow rate due to the wider throat area after the cold-to-hot deformation.