The Study Of The Effects Of Car Door Size Deviation On Interior Aerodynamic Noise

One of the key components in the vehicle, the door is normally opened and closed, the complexity of the system design inevitably leads to size deviation in the manufacturing process. Car door size deviation affects the appearance of the vehicle body, and directly affects the quality and performance of the vehicle, leading to the deterioration of the seal and the increasing of the aerodynamic noise (wind noise). Automobile noise is an important performance index of the whole vehicle, so the noise control is an important issue in the development of the automobile industry. The automobile fault that customers often complained is the wind noise problems; with the development of highway, People travel more and more in high speed, for a long time in the noisy environment is easy to make people tired and irritable, seriously impact on the driving safety and comfort. The generation mechanism and control of wind noise is also a very complex topic, especially, the wind noise must be predicted and analysed in the automotive design stage. In this paper, based on the engineering practice of the dimension deviation and the wind noise in the process of the door manufacturing assembly, the formation mechanism of wind noise is analyzed by analyzing the dimension deviation of vehicle door, A study on the relationship between the vehicle door size deviation and the performance of the wind noise and its noise characteristics and numerical simulation.As the basis for noise signal processing, firstly, the basic theories and methods of signal processing were introduced. This paper mainly introduced the fast fourier transform (FFT) method and the digital filter technology used in this paper. Before the noise test, the relationship between the vehicle door size deviation and the whole vehicle air tightness was tested and analyzed.Secondly, we used noise and vibration acquisition system(BBM) and analysis software (PAK) produced by the German development company Miller fritillary, vehicle road test was conducted, sliding off the engine method was used in the wind noise test of the high speed, real-time signal acquisition and deal with necessary data in the test process. By analysed the time domain data, then the fast fourier transform, and analysed the vehicle wind noise signal by the method of A weighted and total noise 1/3 octave spectrum. The results of the test show, Road wind noise test for evaluation of wind noise is feasible. The research of the door seal on the car interior noise contribution and The relationship on high speed driving under different conditions of various door size deviation form and wind noise in vehicle has been found, The noise frequency characteristics and main distribution characteristics of the vehicle door deviation are determined.Finally, combined with the theoretical knowledge of aerodynamic acoustics, By using the method of numerical simulation of fluid dynamics software FLUENT, The car door deviation of vehicle exterior aerodynamic noise properties were investigated. Numerical simulation based on large eddy simulation (LES) and Lighthill acoustic analogy theory, the vehicle simulation model was established, The steady state was calculated by standard k-? turbulence model, the distribution of the static pressure and the power level in the vehicle body was obtained; The relationship between aerodynamic noise and sound power with wind speed was investigated, The trend is consistent with the change of the dipole source sound power with the velocity; In addition, Numerical simulation of transient aerodynamic noise was used by large eddy simulation and FW-H equation, The aerodynamic noise sound pressure spectrum distribution caused by door size deviation is obtained. Through the comparison of the total sound pressure level on the different sizes deviation of the door. The car aerodynamic noise changes with the difference size deviation of the car door, in early stage of the development of new models to evaluate the aerodynamic noise level and to provide a reference for the active noise reduction design, it will provide reference for the design and manufacturing quality control of the dimension tolerance of the door.