Performance Analysis And Structural Optimization Of Heavy Truck Air Filter Based On Fluid-structure Coupling

With the increasingly prominent problems of environmental pollution and energy and fuel shortage as well as the need of sustainable development,the automobile industry is constantly innovating and developing.As part of the development trend,small and medium-sized passenger vehicles have been gradually electrified to reduce energy consumption and environmental pollution.However,freight vehicles,especially heavy trucks(HGVS),still require diesel fuel to operate.Heavy trucks,although relatively few in number compared to passenger vehicles,have the greatest impact on NO_x and particulate matter(PM)emissions.The air filter is the"lung"of the engine,and its performance parameters mainly include intake resistance,filtration efficiency and noise reduction characteristics,which directly affect the fuel economy and driving stability of heavy trucks.Optimizing the structural parameters of the air filter can improve the performance index,so as to reduce the emission of harmful substances and noise pollution.Therefore,it is very necessary to analyze the performance of the heavy truck air filter.According to the actual structure of heavy truck air filter,"Solidworks"software is used to build the three-dimensional model of air filter and paper filter element.In order to improve the comprehensive performance of air filter,a numerical analysis model of fluid-structure coupling between air filter and paper filter element was established.In"ANSYS"software,the"CFX"module and"Static Structural"module are used to construct the fluid-structure coupling calculation channel,and the fluid pressure,velocity distribution and filter element deformation are visualized.The discrete phase model(DPM)and porous medium model were used to reconstruct the motion trajectory and filtration process of particles in the air filter.According to ISO-5011 standard,the performance test of this type of air filter is carried out.The error between the test results and the simulation results under six flow conditions is less than 4%,which verifies the accuracy of the fluid-structure coupling simulation model.The simulation results show that the air intake resistance of the heavy truck air filter is large(up to 2.20k Pa at the rated flow rate).Due to the influence of factors such as the location of the air inlet pipe,the fluid exerts a large impact on the filter element locally,resulting in the maximum deformation of the filter element in the circumferential direction being 7.8 times of the average deformation,which easily leads to mechanical damage of the filter element and affects the filtration efficiency of the air filter.On the basis of fluid-structure coupling simulation analysis,in order to study the noise attenuation performance of air filter,the acoustic finite element model was constructed by using the pressure acoustic module of"COMSOL Multiphysics"software,and the sound pressure level of air filter in the frequency range of 0-2000Hz was output.Taking the acoustic transmission loss of air filter as the index to evaluate the acoustic attenuation performance,the influence of filter element structure,shell structure and other parameters on the transmission loss was analyzed.It is found that the paper filter element plays a key role in the noise attenuation ability of the air filter in high frequency band above 1300Hz.The loss value of the air filter on the transmission of sound wave is less than 5d B at a specific frequency,and there is almost no noise attenuation effect.Further structural optimization is needed.Based on the analysis of fluid-structure coupling and the study of noise reduction performance,the air filter has been optimized and improved to solve the problems of high intake resistance,large filter element deformation and poor noise reduction effect.The optimization scheme is as follows:Firstly,through the fluid-structure coupling finite element model,the single factor optimization design of air filter intake pipe position,filter element fold number and height is optimized,and the optimal optimization scheme of performance parameters such as intake resistance and filter element deformation is determined.On the basis of this optimization,finite element simulation is carried out on the transmission loss of air filter in the frequency range of 0-2000Hz,and the noise reduction ability of specific frequency is improved by inserting 1/4 wavelength tubes with different diameters.The simulation results of different schemes were compared to determine the final optimization scheme,and the optimized model was imported into"ANSYS"and"COMSOL Multiphysics"for numerical calculation and comparison with the original model.The results show that after optimization,the intake resistance of the air filter is reduced by 20.8%,the maximum deformation and average deformation are reduced by 23.4%and 31.0%,respectively,and the transmission loss at the frequency of820Hz is increased by 28.6d B.