The Influence of Backward Sweep on Aerodynamic Performance of a 1.5-Stage Highly Loaded Axial Compressor

Abstract

As a degree of freedom in three-dimensional blade design of axial compressor, the sweep technique significantly affects aerodynamic performance of axial compressors. In this paper, the influence of backward sweep rotor configurations on aerodynamic performance of a 1.5-stage highly loaded axial compressor is studied by numerical simulation. The aim of this work is to improve understanding of flow mechanism of backward sweep on aerodynamic performance of a highly loaded axial compressor. A commercial CFD package is employed for flow simulations and analysis. The study found that backward sweep had little effect on peak efficiency of the 1.5-stage axial compressor. At the design rotational speed, compared with baseline, backward sweep rotor configurations reduce the blade loading near the leading edge but slightly increases the blade loading near the trailing edge in the hub region. As the degree of backward sweep increases, total pressure ratio and stall margin of the 1.5-stage axial compressor increase first and then decrease. Among different backward sweep rotor configurations, the 10% backward sweep rotor configuration has the highest stall margin, which is about 2.5% higher than that of baseline. This is due to the change of downstream stator incidence, which improves flow capacity near the hub region. At 60% rotational design speed, passage shock disappears. Backward sweep rotor configurations deteriorate stall margin of the compressor, but increase total pressure ratio and adiabatic efficiency when flow rate is lower than that at peak efficiency condition. Therefore, it's necessary to consider flow field structure of axial compressors in the design process and use the design freedom of sweep to improve the aerodynamic performance.