Influence Of Operation And Geometric Uncertainty On Heat Transfer And Pressure Drop Of Centrifugal Compressor

Centrifugal compressor is widely used in energy,petrochemical,aerospace,transportation and other engineering fields.Its performance is affected by many factors during operation.At present,the numerical simulation of the performance of centrifugal compressor adopts the deterministic research method.Because the operating conditions of centrifugal compressor are more complex,the influencing factors have certain uncertainty,so the research of the performance of centrifugal compressor should consider the influence of this uncertainty.Based on the stochastic collocation method,the flow uncertainty of the head cover driven flow and the performance uncertainty of the centrifugal compressor are studied.The specific research contents and conclusions are as follows.Based on the stochastic collocation method,a quantitative analysis method for the flow uncertainty of head cover driven flow is developed.Firstly,the stochastic collocation method is used to generate the random collocation points of uncertain parameters.Secondly,the polynomial output method is used to decompose the random output field and form polynomial chaos to expand the random output field.Then,CFD is used to carry out the numerical simulation of uncertainty quantification.Finally,the statistical characteristics and sensitivity analysis of the stochastic output field of the top cover driven flow are solved based on the regression analysis method.The results show that the top cover driving speed and the bottom cover driving speed have the greatest influence on the flow field and pressure field in the cavity,and the areas with the largest standard deviation of velocity and pressure are concentrated near the top and bottom walls and in the middle of the cavity.A quantitative analysis method for performance uncertainty of centrifugal compressor based on stochastic collocation method is developed.Based on the non-invasive multinomial chaotic expansion method,the process parameters with uniform probability distribution are obtained.The characteristic indexes of centrifugal compressor are calculated by MATLAB program.The analysis results of characteristic indexes show that the non-invasive multinomial chaotic expansion method has high confidence,which can be used as the value basis of uncertain parameter distribution.The results of mean and variance of flow field uncertainty of centrifugal compressor show that the uncertainty of process parameters has the least influence on the temperature distribution of centrifugal compressor.From the temperature variance,it can be seen that the temperature distribution will form a certain deviation,especially in the blade near the impeller.The sensitivity analysis of boundary parameters on the performance and flow field of centrifugal compressor shows that the inlet mass flow rate has the greatest influence on the temperature change,followed by the total pressure at the outlet;On the sensitivity of pressure field distribution and blade pressure field in centrifugal compressor,the inlet mass flow rate has the greatest influence on the pressure change,followed by the outlet total pressure,then the influence of speed,and finally the outlet total temperature.The uncertainty quantitative analysis method proposed in this paper has important theoretical significance for improving the performance of centrifugal compressor and evaluating the stability of centrifugal compressor operating conditions.