Performance Analysis and Aerodynamic Design of Axial Flow Compressors

Abstract

The main objective of the paper is to analyze the performance of axial flow compressors and to generate a systematic design approach which enables to design subsonic flow ones. In order to investigate the validity of this approach, the LP axial flow compressor of the RR Spey MK511 turbofan engine is taken as an example. The design calculations were based on thermodynamics, gas dynamics, fluid mechanics and empirical relations. The flow is assumed to be of two-dimensional compressible type with constant axial and rotor blade velocities with a free-vortex swirl distribution. Design calculations include thermodynamic properties of the working fluid, number of compressor performance parameters such as, stage temperature rise and number, flow and blade angles (blade twist), velocity triangles and relative inlet Mach number at rotor blades tips as well as blades tip and hub diameters. A repeated calculation is made to determine these parameters along compressor stages. The variation of velocity whirl components, air and blade angles, deflection and degree of reaction from root to tip of the blades were also determined. The twist of the blades along the blade length is set according to the recommended values in order to obtain smooth blade twist profile.