The Similarity Analysis And Optimation Of Aerodynamic Performance On A Centrifugal Compressor Stage

The centrifugal compressor is a kind of turbomachinery widely used in chemical industry,energy engineering and aerodynamics for the advantage of high efficiency,high velocity and wide operating range.During operating process of the centrifugal compressor in chemical industry,we need to understand the aerodynamic performance of different real gases in compressors.The purpose is to verify the performance of the designed gas through the aerodynamic performance of different real gas.With the requirements of energy-saving and emission reduction in the chemical field,it is very important to improve the performance and increase the working condition by optimizing various components of the centrifugal compressor.Aiming at performance test of real gas in compressors,this paper focuses on the applicability of different real gases aerodynamic performance for a compressor model stage and analyzes the influence of different real gases on the centrifugal compressor's aerodynamic performance.Firstly,based on the conformity verification between the numerical simulation and the experimental results,the numerical method is adopted to compare and analyze the aerodynamic similarity and variation law of compressor stage with air working medium and R134a? CH4 real gas medium separately,that the operating rotation speed are both the equivalent rotation speed and variable rotation speed.The results demonstrate that whether the design point or the off-design points are regarded as the base point of equivalent conversion,the equivalent rotation speeds are pretty much to be same,and the polytropic efficiency and energy head coefficient curves of the compressor stage for the different real gases medium also agree well with that of the original gas medium.Taking the gas of CH4 as an example,the subsonic performance curves and the working range at different Much numbers almost display the same distribution trend at variable rotating speeds.But for transonic flow,the maximum efficiency value of performance markedly moves towards the working condition of large mass flowrate,and the higher Mach number,the more narrow the operating range.As a result,the performance curves no longer meets the law of similarity at transonic rotating speeds.In view of the mutual influence between flow part and internal flow for compressor,the stagger angle of centrifugal compressor diffuser has been optimized using the genetic algorithm under stage environment.The aerodynamic performances of the compressor are numerically compared before and after optimization.The results show that the variable efficiency,the total pressure ratio and the static pressure recovery coefficient of the diffuser are increased by 1.62%,1.59% and 16.23%,while the total pressure loss coefficient of the diffuser is reduced by 23.66%,and the whole stage performance of the compressor is improved greatly in the range of the whole flow rate condition after optimization,especially in the large flowrate range.The study on the equivalent similarity conversion rule of different real gases in the centrifugal compressor and the optimization of the compressor's components have carried on helpful exploration and it also has important guiding significance for aerodynamic design and application of centrifugal compressor.