Investigation Of Effects Of Inlet Swirl On Performance And Stability Of Axial Compressor

The design of compressor components is usually carried out on the premise of uniform inlet flow field.In the actual working process,compressor almost operates under non-uniform inlet conditions,i.e.under the distorted inlet conditions,which deteriorates extremely its performance.With the renewal of fighter aircraft and the increasing complexity of intake system,the impact on compressor by swirl distortion is more and more prominent and could be notable concern.When comparing the existing knowledge of total pressure distortion and total temperature distortion,swirl distortion and its effects on performance and stability of compressor are poorly understood.Therefore,the study of the effects of swirl distortion on the axial compressor has a very important significance.The main goal of this master's research is to further the current knowledge on paired swirl distortion,and its effects on compressor performance,focusing on the influences of the swirl distortion on the flow field of the compressor.Taking the transonic rotor Rotor37 with detailed experimental data as the research object,and relying on the numerical simulation tool NUMECA,a full-annulus unsteady numerical simulation of the effects of swirl distortion on performance and stability of transonic rotor was carried out with simplified twin paired swirl distortion as the main type of swirl distortion.The numerical results show that the performance of the rotor is deteriorated with paired swirl distortion,and its stable operating range is reduced;Circumferential flow due to paired swirl distortion tends to make the circumferential distribution of the inlet variables such as static pressure,meridian velocity and other flow parameters become non-uniform;The circumferential relative intensity of swirl distortion decreases along the axis,and the maximum decrease occurs after passing the rotor blades;In addition,due to the variation in work input,the total temperature and total pressure distribution of the outlet become non-uniform;The major factor of compressor's instability is that circumferential non-uniform swirl angle causing the excessive load in some passages resulting in the interaction of high-intensity leakage vortex and shock wave contribute a large blockage in the tip region.A numerical study was carried out on inlet guide vanes(IGVs),which is one of methods for reducing swirl effect,in order to determine IGVs' capabilities for reducing twin swirl distortion and the factors affecting its effect.The results show that the reducing swirl effect of the IGVs is not inevitable,and the effect is related to the inlet swirl intensity and its own solid.The higher the solid,the smaller the swirl intensity and the better the reducing effect would be.In addition,high-intensity swirl distortion tends to cause flow separation and resulting in additional losses,which is harmful to rear aerodynamic components.Finally,based on the above research,a circumferential rotating swirl distortion generator is designed,and experiments on the effect of swirl distortion on the performance of low-speed multistage compressor are carried out on a two-stage low-speed axial compressor platform.The reliability of the unsteady numerical method in this paper is verified by the variation trend of the overall characteristics of the compressor under the effect of the experimental swirl distortion.