Active Control Simulation Research Of Bus Interior Noise Based On Acoustic Modal

In recent years, ride comfort of bus is concerned by passengers gradually. How to reduce interior noise has become a hot spot in the field of automotive research. Compared to the traditional passive noise control technology,active noise control technology works better in the low frequency noise, which causes less influence in structure of car. Therefore,the application of active noise control method has important research significance in controlling low frequency noise inside the car.In view of the influence to sound field caused by the change of source characteristics,this article changes the parameters of the sound source sequentially,and analyzes the change of sound pressure,phase as well as the response distribution to sum up the influence rule. According to the leading acoustic modal vibration mode of acoustic response, acoustic modal analysis method is adopted in the low frequency sound field of bus.Then this article analysis the spatial distribution of noise in resonance frequency,derivating the controlled space and characteristics of sound field. Based on the acoustic modal theory,secondary sound source location is studied by calculating the acoustic response which is caused by a virtual engine sound radiation. Change trend of the sound field is derived under the influence of secondary sound source location, amplitude and phase,combining with the principle of minimum space energy. The change rule is verified by finite element model of simplifyed bus interior sound field. In the simulation engine noise field, the energy of the dominant modes are compared after constant debug of secondary sound source location according to this change trend,by which the secondary source location optimization rule is proposed.Finally, active noise control in bus interior sound field based on road incentive is simulated. After establishing passenger carriages simplified three-dimensional geometric model. The carriage structure and internal tunes are discreted by Hyper Mesh pre-processing software. To simulate road excitation,white noise force excitation is loaded in four suspension points of the body. Under the condition of this incentive, the interior acoustic response is calculated within the frequency range of 50 Hz ~ 200 Hz. Aiming at the peak response, secondary sound sources are loaded in accordance with the location optimization rule,to achieve the purpose of passenger car active noise control. It is verified from the simulation result that active noise control technology runs well. Under the condition of laying appropriate number of secondary sound source in appropriate place and adjusting their amplitude and phase.In this paper, the secondary sound source cloth optimization scheme can effectively reduce the interior noise,control effect the bus interior noise can be reduced to the desired control objectives by active noise control secondary source location optimization rule that is proposed.