Research On The Generation Mechanism And Control Of Vehicle’s Wind Buffeting Noise

With the development of China’s automobile industry and the improvement of people’s living standards,consumers’ car buying concepts are becoming more mature,and people are paying more attention to the vehicle ride comfort.The noise inside the car is an important indicator for evaluating the vehicle ride comfort.While driving,due to the needs of ventilation and defogging,low-frequency and high-intensity wind-vibration noise will be generated when the windows are opened.The wind buffeting noise can easily bring discomfort to the driver and passengers,and seriously affect the vehicle ride comfort and driving safety.Therefore,it is very important to study the generation mechanism,influencing factors of wind buffeting noise and control of it.This article starts with a general model.First,a geometric model of a simple cavity was established and numerical simulation was performed.The simulated value was compared with the experimental value to verify the accuracy of the simulation result.Then,the generation mechanism of wind buffeting noise was analyzed based on the theory of acoustic resonance of the cavity noise and the feedback of the opening.It was found that the wind buffeting noise is the result of the feedback mechanism and acoustic resonance.The periodic shedding of the vortex will cause the pressure inside the cavity to change periodically,resulting in wind buffeting noise.However,the cavity itself has a natural frequency.Helmholtz resonance will be produced when the frequency of the vortex shedding is close or the same as the natural frequency,which will further aggravate the pressure fluctuation in the cavity and intensify the wind buffeting noise.This provides as reference for the actual vehicle study of the mechanism of wind buffeting noise.Then,by changing the size of the cavity opening,the characteristics of wind buffeting noise under different characteristic lengths of the cavity opening were explored,and it was found that the frequency of vortex shedding was locked near the natural frequency,and with the increase of the incoming flow velocity at a certain characteristic length,the shedding of the vortex may change from a high mode to a low mode,resulting in discontinuous changes in the frequency of wind buffeting noise;When the incoming flow velocity is constant and the vortex shedding is in the same mode,the greater the characteristic length of the opening,the smaller the frequency of the peak of wind buffeting noise,but there is no regularity between the sound pressure level and the characteristic length.Therefore,it is necessary to analyze the flow field to provide a reference for the subsequent research on the characteristics of wind buffeting noise under different openings of actual vehicle windows.After that,the wind buffeting noise characteristics of the side window of one SUV were studied.First,a wind tunnel test was performed,and then the SUV was simulated by a numerical simulation method.The simulation value was compared with the experimental value to verify the accuracy of the numerical simulation and analyze the mechanism of wind buffeting noise from side windows.The influence from different opening methods of side windows on wind buffeting noise was studied,and it was found that when a single side window was fully opened,the wind buffeting noise was the most obvious,and the wind buffeting noise when the rear side window was opened alone was higher than when the front side window was opened alone.The wind buffeting noise when two side windows are opened at the same time will be lower than when one side window is opened alone.The reasons for the differences in wind buffeting noise under different opening methods were analyzed.The method of setting spoiler and center column in the side window were used to control the wind buffeting noise,and the reason why it can usefully control the wind buffeting noise of the side window was analyzed from the flow field.Finally,a numerical simulation method was used to study the wind buffeting noise characteristics of the same SUV.The mechanism of the characteristics of wind buffeting noise of the sunroof was analyzed,and the characteristics of wind buffeting noise under different opening degrees of the sunroof were compared and analyzed.With the increase of opening degree of sunroof,the sound pressure level of wind buffeting noise is getting higher and higher.A deflector and an air jet installed at the front edge of the sunroof can effectively control the wind buffeting noise.Through analyzing its noise cancellation ability,a method of active control of reverse pressure was put forward,which can basically eliminate wind buffeting noise.