Study On The Influence Of Complex Flow And Key Structure Changes On The Performance Of A Certain Type Of Centrifugal Compressor

The 21st century is an era of massive energy consumption.Only by paying attention to energy conservation and emission reduction,the development of new energy and the reuse of renewable resources,can we win a head start in future development.At present,the power of a large single centrifugal compressor unit can reach tens of thousands of kilowatts.Improving its overall aerodynamic performance and reducing energy consumption is of great significance to the sustainable development of a country’s major equipment manufacturing industry.Obviously,in order to design a high-performance centrifugal compressor,it is necessary to have a thorough understanding of its internal flow structure and energy loss mechanism.However,the internal flow of centrifugal compressor is affected by rotation,curvature,viscous and other factors,and the flow phenomenon is very complex.The flow problem of centrifugal compressor involves not only three-dimensional viscous compressible flow,but also inherent unsteady flow problem.At present,the domestic research in this area is not very perfect.For this reason,the influence of the change of intake condition/working medium and key structural parameters on the aerodynamic performance of a large centrifugal compressor has been investigated in this paper with numerical simulation and theoretical analysis simultaneously.Based on the data of a large number of simulation results,internal relationship between geometric structure parameters and the compressor’s aerodynamic performance parameters is established.Both the main factors affecting the aerodynamic performance of centrifugal compressor and the detailed influencing mechanism have been found.The results show that:(1)temperature,pressure,rotational speed and working medium have great influence on the performance of centrifugal compressor.The decrease of temperature,the increase of pressure,the increase of rotational speed and the increase of molecular weight of working medium all can make the stable working range of the compressor move towards large flow;(2)the shape of meridian channel has great influence on its internal flow structure,and optimal meridian channel can avoid internal flow separation;(3)width of the diffuser outlet is closely related to the internal flow field.Reduction of the diffuser’s outlet-width can effectively suppress the flow separation near the wall as well as improve the efficiency and total pressure ratio of the centrifugal compressor;(4)The reduction of impeller’s outlet width is helpful to improve the compressor’s efficiency as it working near the surge or blockage point.At the same time,both the separation at the suction surface of the impeller blade and the radial velocity distribution in the diffuser part improve a lot after width of the impeller’s outlet decrease a little;(5)In the large part of the working range,rotary diffuser can make the flow field in the diffuser more uniform and improve the performance of centrifugal compressor.However,in the large flow area,its effect is opposite;(6)Different combinations of blade numbers can greatly affect the efficiency of the centrifugal compressor.