A Study On The Low Aerodynamic Noise Performance Analysis And Control Of Engine Cooling Axial Flow Fan

The great convenience has been brought to humans by the development of automobile industry, at the same time, the resulted exhaust and noise pollution and the shortage of energy source raised the comprehensive concentration. Cooling fan as an important noise source of automobile, its low noise aerodynamic performance design has been increasingly important with the issue of new noise regulation.This paper aimed at the low noise aerodynamic performance of automobile cooling fan, set out from the fluid dynamics and the mechanism of noise generation and radiation, mathematical model has been erected to analyze the influence of the main structural parameters on noise performance. According to the forward problem of impeller machinery design, calculation software was developed to get the main structure parameters of cooling fan, and optimum design schemes was selected from the many alternatives to manufacture the rapid prototyping model for the experiment. At the same time, according to the reverse problem of impeller machinery design, focusing on the noise performance, the counter calculation software was developed to estimate the noise of cooling fan to provide the elementary verification of the design effect.A specialized noise test bench of automobile cooling fan was designed to carry out the bench test and the outer vehicle acceleration noise test also was conducted. The bench test indicated that noise of the designed cooling fan was apparently decreased. At the important revolution, 3~4.5dB(A) noise decrease can be expected in the bench test and 1.5~2dB(A) decrease in the acceleration noise test. With the modification of shroud, a better result can be expected. But it was not verified by the limit of experiment condition.With the rapid development of numerical technology and CFD simulation, the numerical technology for the forward problem of impeller machinery design had a good investigation and application, but the turbulence model need to be improved. For the lack of fund and the lagging behind of the technological consciousness, the job was insufficiently conducted domestically. In order to exploit the application of modern design method to fan design, this paper discussed the CFD calculation and groped the theory and practice of CAA.