Centrifugal Compressor Design And Flow Characteristics Research

Centrifugal compressors are widely used in micro turbojet engines and turbochargers due to their simple structure and high single-stage pressure ratio.According to the design requirements of a low specific speed centrifugal compressor,combined with the design method of the centrifugal compressor,this paper completes the preliminary design of the compressor,and completes the study of the compressor flow field flow characteristics and internal flow rules through numerical calculations,and analyzes the low ratio.The performance of the rotational speed centrifugal compressor changes with the typical geometric parameters and configuration of key components.The main research contents of this paper are as follows:1.Complete the preliminary design of the compressor.According to the design requirements,use MATLAB to compile the one-dimensional geometric parameter design interface of the compressor,complete the basic design of the compressor through the given design parameters,and complete the three-dimensional modeling of the compressor according to the obtained parameters and the CFTurbo software;2.In order to improve the total pressure ratio and isentropic efficiency of the designed centrifugal compressor,optimize the design of the whole centrifugal compressor.First,the one-dimensional performance prediction method based on the loss model is combined with the uniform design method to complete the establishment of the centrifugal compressor sample library;then the one-dimensional multi-objective optimization of the centrifugal compressor is completed through the combination of BP neural network and NSGA-II,And get the corresponding Pareto frontier solution set;finally,numerically calculate the results before and after the optimization to verify the effectiveness and feasibility of the optimized design.The optimization results show that the errors of the optimization results of the established optimization models are all within 5%,the pressure ratio of the optimal individual is81.3% higher than that of the initial individual,and the efficiency of the optimal individual is 10.98% higher than that of the initial individual.And the pressure ratio of the most efficient individual is also 10.8% higher than the initial individual.3.According to the optimization results,select the best efficient individual to study the flow characteristics of the compressor impeller,there are the inlet hub ratio,outlet width-to-diameter ratio,inlet diameter ratio,blade wrap angle,blade back bending angle,number of blades,and tip clearance.The impact mechanism of the impeller tip is studied in all aspects.The results show that for low specific speed centrifugal compressors,the hub ratio,width-to-diameter ratio,and diameter ratio have the greatest impact on the performance of the compressor,all of which are changing the flow capacity in the impeller flow passage,due to the low specific speed centrifugal compressor.The reverse pressure gradient is larger,and the backflow effect after increasing the flow capacity is strengthened,so that the loss is increased,and the performance of the compressor is also affected;the blade wrap angle has the smallest impact on the performance of the compressor,regardless of the influencing factor down,the pressure ratio will be affected to a higher degree.4.The influence mechanism of the static diffuser section of the low specific speed centrifugal compressor is studied.The different diameters of the vaneless diffuser section,the different contraction angles of the vaneless diffuser section,the different contraction modes of the vaneless diffuser section,and the different surface diameters of the volute.The performance and flow characteristics of the relative centrifugal compressor are explained,and the causes and laws of the results are analyzed.The results show that the compressor performance is most affected by the volute surface-to-diameter ratio.The volute throat with reduced volute surface-diameter ratio is more likely to produce compression waves.The kinetic energy of the gas after compression waves is significantly reduced,but the inside of the diffuser The vortex motion is also more intense;for the vaneless diffuser section,the diameter of the diffuser section has an optimal value range;and the contraction angle of the retractable diffuser section reaches a certain level,and the compressor performance is improved.There is no big difference in performance between different shrinkage methods.