| As people's requirement of the automobile quality improving, the noise of the vehicle is paid more and more attention. Many automobile manufacturers and scientific institutes are doing research on vehicle's NVH(Noise Vibration & Harshness). Many countries have promulgated redaction which limit vehicle noise below a certain level. Our government constituted and enacted National Standard GB1495-1979"The allowable noise measurement of motor vehicles"at 1979 for the first time and made a recension on the base of the original redaction refer to Europe Union ECE Reg.No.51 at 2002 which called"The limits and measurement of exterior accelerating noise of vehicles". Therefore, it's very necessary to debase the vehicle noise.Vehicle noise is produced by the engine(source of power), the wiring components(inclode the cooling fan and the dynomotor), the frame(supports the engine, wheels, steering, brake systems, and body), the power train (carries the power from the engine to the wheels) and the car body. Among them engine noise occupies more than a half, however, the noise of the cooling fan is also an important constituent especially that of the heavy-duty truck'.This study is based on the item named"The technology of simulation and analysis on the capability of the cooling fan and exhaust muffler", whose sub-project named"The advanced technology of integration and exploitation for the heavy commercial vehicle". Because of the poor performance of cooling system, the CFD simulation study on the high mass flow rate and low niose cooling fan is needed. At least two improved projects and a simulation arithmetic need to be proposed. In order to meet the need of the item, first, according to the test method about aerodynamic performance and aerodynamic noise on the cooling fan in FAW Technology Center, aerodynamic performance and aerodynamic noise are tested under five different speeds. The results of aerodynamic performance and aerodynamic noise have been noted. The static pressure, the input power, the static pressure efficiency and the SPL (sound pressure level) curves. refer to mass flow rate were gained. Second, do some research on the arithmetic. Keep the boundary condition the same with actual condition as far as possible. And then gained the exact arithmetic after doing a lot of calculation. The result indicates that the error of mass flow rate and noise is less than 5﹪, so consider that the arithmetic is advisable. Third , change the structure parameters of the fan, and construct a number of three-dimensional geometric fan models. After the simulation to the mass flow rate and noise, summarize the orderliness about which the structural parameters of the fan work on the mass flow and noise. And then rebuild the three-dimensional geometric fan models, and then calculate again. Finally choose two better effect projects.Mass flow rate of the first project increases by 4﹪～5﹪, and the noise reduces by 5.1dB at the speed 2500r/min. Mass flow rate of the second project increases 7﹪～9﹪, more than the first project, but noise decreases only by 3.5 dB, less than that of the first project. In a word, the effect of the two projects is quite perfect. If it can be put into use, it will not only improve the cooling effect, but also reduce the noise pollution.Considering actual needs, the diameter of the fan is fixed, only change the fan's blade profile and installation angle. However, the angle is a bit of random, it maybe not the best. There're many factors that affect mass flow rate and noise, so the better project is to be studied further.
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