Study On Modeling Design And Optimization Of Centrifugal Compressor

As an important part of micro gas turbine,the research and development of centrifugal compressor with superior and reliable performance is of great significance to the development of advanced micro gas turbine technology.Similar modeling design method has the characteristics of time-saving and high reliability,and its application and research in the design of centrifugal compressor are relatively few.Therefore,it is of practical significance to carry out the research on the modeling design law and mechanism of centrifugal compressor.In addition,the mechanism of tip clearance effect on the modeling process is not clear.Through the influence of different tip clearance on the internal flow and overall performance of the modeled compressor,it is found that the influence mechanism of tip clearance on the modeled compressor has application value.Furthermore,the performance of the centrifugal compressor can be further improved by using the optimization algorithm.Based on this,this paper mainly carried out the following research contents:First of all,based on the prototype compressor,the model compressor is designed according to strict geometric similarity.The overall performance of the model compressor and the prototype compressor at 80%,90%,100% and 110% rotation speed were studied.The internal flow of the design condition and the blocking condition at 100% roration speed were compared and analyzed.The results show that the size and strength of the vortex in the diffuser are less than that in the prototype compressor,and the blocking effect of the low-speed fluid group formed by the vortex on the flow passage is reduced.The low-speed fluid group moves the compressor blocking point to the right,and the working flow range is enlarged,The flow margin increase of 100% rotantion speed is more than 2%.In the boundary layer,the Reynolds number of the working fluid is less than the critical Reynolds number,which does not meet the flow similarity condition.The Reynolds number in the boundary layer of the modeled compressor is higher than that of the prototype compressor,and the flow is less affected by viscosity,so the flow loss in the boundary layer is lower than that of the prototype compressor.Then,the overall performance and internal flow field of the model compressor with tip clearance height of 0.2mm,0.25 mm and 0.3mm are studied.The results show that when the tip clearance width is 0.2mm,the aerodynamic performance of the modeled compressor is the best.Reducing the tip clearance can reduce the flow nonuniformity,and vortex can improve the flow passage blockage.Finally,the back propagation algorithm and genetic algorithm are used to optimize the rake characteristics of the impeller blades,and the forward rake impeller profile is obtained.The results show that the flow margin of the optimized compressor has been greatly improved at each speed,especially at 80% rotation speed,with the maximum efficiency increased by 3% and the flow margin increased by more than 100%.At 100% rotation speed,the adiabatic efficiency slightly increased,and the flow margin increased by 6.63%.The forword rake of blade can restrain the low-speed flow at the end wall,improve the flow condition in the impeller and increase the stability of the whole compressor.