Research On Three-Dimensional Aerodynamic Optimization Design Of Centrifugal Compressor Volute

The centrifugal compressor of compressed air energy storage system has the characteristics of high single-stage pressure ratio,wide range of operating conditions,compact structure and stable operation,which has a decisive impact on the operating performance of the energy storage system.As one of the important parts of centrifugal compressor,the outlet volute has a direct and non-negligible influence on the overall performance and working range of the compression system due to the complete threedimensional turbulent internal flow.It is of great significance to understand the internal flow and loss mechanism and the influence law of cross-section parameters for volute design and system performance.Therefore,the three-dimensional aerodynamic optimization design of the outlet volute of centrifugal compressor in compressed air energy storage system will be studied in this paper.The main contents of this thesis are as follows:(1)Researching on the aerodynamic matching design of outlet volute.Based on the equal angular momentum design theory,an efficient matching design system of outlet volute,impeller and vaned diffuser was established for external volute with tangential inlet.The design results show that the overall isentropic efficiency and total pressure ratio of the centrifugal compressor are significantly improved,and the vortex flow structure in the volute channel is improved,with increased stable operating range and reduced internal pressure loss.(2)Investigating three dimensional parameterized design method of outlet volute.Referring to the designed circular external volute with tangential inlet,the crosssectional parameters of centrifugal compressor volute are constrained by multiple control surfaces and control points.The single cross-sectional shape is controlled by six design variables,and the design parameters are dimensionless.A parameterized design method of variable cross-sectional shape is proposed.(3)Exploring the multi-objective optimization design of outlet volute.Firstly,the optimal Latin hypercube design method is used to analyze the global sensitivity of design variables,and the range of design variables is determined.Then,the centrifugal compressor with parameterized volute is taken as the calculation model,and the sample space is generated by combining the optimal Latin hypercube design method and full three-dimensional CFD method,and the Kriging approximation model between design variables and target performance is constructed Finally,taking the total pressure loss coefficient and static pressure recovery coefficient as the optimization objective variables,NSGA-II algorithm is used to carry out the three-dimensional multi-objective optimization design of the centrifugal compressor with parameterized cross-sections of the volute.Base on the above all,the aerodynamic optimization platform and optimization method of the centrifugal compressor system are established,and the multi-objective optimization of the outlet volute is realized.The results show that the static pressure recovery coefficient of outlet volute is increased by 5.52%and the total pressure loss coefficient is reduced by 11.24%after single section optimization in the design condition.Compared with the initial design,the overall isentropic efficiency and pressure ratio are increased by 0.45%and 0.36%.The optimized teardrop shape can reduce the shear stress in the vortex center,and make the meridional velocity distribution more uniform in the outlet volute.After multisection optimization,the isentropic efficiency and pressure ratio of whole stage are increased by 0.55%and 0.45%respectively,and the diffusion capacity of the outlet volute is further improved.This study establishes an effective aerodynamic optimization design method for the outlet volute of centrifugal compressor,which has good engineering application value.