Research And Control About Aerodynamic Noise In Passenger Compartment Of A Car

Ride comfort is closely linked with internal noise induced by aerodynamic noisewhen the car travels at a high speed. According to research, people chronicallyexposed to noise tend to be struck by disorders like tinnitus, anxiety,progressive cognitive and even deafness, so automobile manufactures and customershave higher and higher demand for internal noise. Besides, the problem that internalnoise mismatches market positioning of the vehicle will seriously affect the generalimpression on automobile brands. Improving cabin acoustic environment andreducing internal noise have been a hot topic of car research in recent years.Therefore, calculation and effective control about aerodynamic noise in passengercompartment of a car become a matter of great significance.Research on internal noise with a car at a high speed is conducted through realmotor road tests and numerical value simulating. Main contents of the research are asfollows:1. Real motor road tests were carried out using a specific car. Moreover, it wasdiscussed that the relationship among aerodynamic noise, A-weighted noise and car’sspeed in the position near driver’s ears and right ear of a rear passenger.2. Air flow near the car was simulated using different kinds of turbulent models,and the most accurate one was screened out compared with wind tunnel experiments.Then, the fluctuation pressure on carbody was simulated through the most accurateturbulent model.3. Statistical energy analysis (SEA) model of a vehicle was established.Fluctuation pressure and model’s basic parameters, that is, modal density, dampingloss factor and coupling loss factor were calculated. What’s more, noise spectrum ofdriver head sound cavity was obtained and the validity of the SEA model was finallyverified compared with real motor road tests.4. Sound absorption materials were arranged on the part which contributed mostto driver head sound cavity. Take the four-layer material for example, an overallevaluation of decline in SPL, material mass, noise reduction efficiency, price ofmaterial and performance to cost ratio was compared between a single layer materialand the multilayer, and the result showed the multilayer had better comprehensiveperformance. 5. The thicknesses of four-layer materials were chosen as design variables. Thedecline in SPL of driver head sound cavity, material mass, noise reduction efficiency,price of material and performance to cost ratio were chosen as optimization targets.Then multi-target optimization was performed based on genetic algorithm. It wasshown that compared with original material combinations, the decline in SPL reducesby3.15%, material mass reduces by1.81%, noise reduction efficiency increases by5.05%, price of material decreases by23.42%, and performance to cost ratio increasesby34.69%.