Research On Aerodynamic Noise Of Automobile Passenger Compartment Under Gas-liquid Two-phase Flow Conditions

Nowadays,more and more scholars and experts are committed to the study of automotive wind noise.They provide many new research ideas and key points in the causes of wind noise,research methods,prediction and control of aerodynamic noise inside vehicles,starting from experiments,theoretical analysis,and numerical simulation.However,research on automotive wind noise is limited to studying the aerodynamic noise generated by airflow separation,which only considers the aerodynamic noise under single-phase flow conditions.When a car is driving,it often encounters rainy weather.At this time,the external flow field of the car belongs to the gas-liquid two-phase flow condition,and the two-phase flow pulsating pressure field is different from the single-phase flow pulsating pressure field when only air is present.Therefore,the aerodynamic noise generated will change.This article is based on this,taking a real vehicle as the research object,and using numerical simulation methods and real vehicle road tests to explore the aerodynamic noise characteristics of the passenger compartment under gas-liquid two-phase flow conditions.This study can provide a reference for the analysis of aerodynamic noise of vehicles in multiphase flow.The main research content of this article is as follows:Firstly.Based on wind tunnel tests,the accuracy of the Realizable k-ε/LES model in simulating automotive flow fields was verified using the MIRA model as the research object.Secondly.Taking a real vehicle model as the research object,the Realizable k-ε/LES model is used to simulate the single-phase flow field under no rain conditions,and a DPM model is added to simulate the two-phase flow field under rain conditions.Analyze the CFD calculation process of the external flow field of the actual vehicle,mainly including the principle of grid division,analysis of continuous phase boundary conditions,and derivation of discrete phase boundary conditions.Grid independence verification was conducted to ensure the accuracy of the actual vehicle flow field analysis.Based on the simulation results of the pressure field on the vehicle surface,the FW-H method was used to calculate the average fluctuating pressure spectra of each subsystem on the vehicle surface under four rainfall conditions.Thirdly.Establish a hybird FE-SEA model of the whole vehicle,calculate the three key parameters of modal density,internal loss factor and Coupling loss factor,take the average fluctuating pressure spectrum of each subsystem of the body surface as the input excitation,and numerically simulate the sound pressure level at the driver’s ear under four rainfall conditions at the speed of 110km/h.Fourthly.By conducting road tests on a certain vehicle model,the variation of aerodynamic noise pressure level inside the vehicle with rainfall and vehicle speed was studied,and the simulation results were compared with the experiments,The simulation results were compared with the experiments,The results showed that at the same vehicle speed,the total sound pressure level near the driver’s ear was the highest under no rain conditions,the lowest under heavy rain conditions,and the total sound pressure level near the driver’s ear was similar under light and moderate rain conditions;In the range of 20-630Hz,the simulation results of the sound pressure level near the driver’s ear are in good agreement with the experiment.In the range of 630-1000Hz,the simulation results have a significant error with a maximum error of 13.3dB.