Aerodynamic Performance Optimization And Noise Characteristics Analysis Of Centrifugal Fan Based On Blade Load Distribution

The main function of a centrifugal fan is to convert mechanical energy into gas energy,and the impeller,as the main component for work in a fan,plays a key role in the overall aerodynamic performance of the centrifugal fan.The optimization of the impeller has always been a major focus in fan design,and the complex internal flow state of the centrifugal impeller and the interdependence of parameters that affect aerodynamic performance make the design of highperformance centrifugal fans challenging.With the continuous development of computer technology and turbulence theory,computational fluid dynamics has gradually become the main method for optimizing centrifugal impeller design.However,the complex parameters in centrifugal impeller design often require a large number of numerical calculations as a basis for optimization.In order to address these issues,this paper uses a full three-dimensional inverse problem design method to control the blade geometry and establish a centrifugal fan impeller optimization design process.The main contents of this paper are as follows:Combining the blade equation design theory in the full three-dimensional inverse problem of the centrifugal impeller parameterization and the multi-objective optimization design method,a centrifugal fan impeller optimization design framework is established and applied to the optimization design of a centrifugal fan.The optimization objectives are the total pressure efficiency,static pressure efficiency,and total pressure,which represent the performance characteristics of the fan.The Morris global sensitivity analysis method is used to establish the sensitivity analysis between design variables and objective functions.This method not only obtains the degree of influence of a single design parameter on the objective,but also identifies the contribution of interaction between design parameters to the objective.The results show that the leading edge load DRVTS of the blade load distribution on the cover side of the impeller is is the main influencing parameter on the total pressure efficiency of the fan;the total pressure of the fan is more sensitive to the change of the slope in the middle of the blade loading distribution;for the static pressure efficiency of the fan,it is mainly affected by the slope SlopeH of the middle straight line segment in the blade loading distribution.The overall performance of the fan before and after optimization is compared,and the optimization results show that the blade loading distribution after optimization is of the backloading type,the mid-span deflection of the fan blade increases,which is more in line with the development trend of the streamline inside the impeller;the flow separation phenomenon on the surface of the blade near the cover is suppressed,the secondary leakage flow phenomenon at the trailing edge is improved,and the effect of converting kinetic energy into pressure energy inside the volute is improved.The total pressure efficiency is increased by 2%,and the static pressure efficiency is increased by 1.4%.This proves the accuracy of the multi-objective optimization design process of the centrifugal fan established in this paper.Abetter design scheme is selected from the optimized fan samples,and a flow-acoustic j oint calculation method is used to evaluate the aerodynamic noise and far-field radiation noise of the centrifugal fan and compare it with the original model.The results show that starting from the tongue,the total sound pressure level of the noise gradually decreases along the direction of gas flow,and the vibration displacement generated at the back cover plate of the volute is the most prominent;the population in the optimized sample can achieve the goal of reducing noise while improving the performance of the fan.Further exploration of the relationship between internal flow field parameters and noise characteristics of the fan reveals that the outlet average velocity of the impeller has the highest correlation with the fundamental frequency noise of the aerodynamic noise;the correlation between the vortex distribution on the middle plane of the volute and the total sound pressure level of the far-field noise reaches 0.9,and the higher the sound pressure level radiated outward from the local high vorticity area near the wall surface in the volute plane.The above conclusions can provide some design ideas for fan noise reduction.