Numerical Simulation Of Aerodynamic Noise Characteristics For Engine Compartment Fan

With the improvement of people’s living standards and material needs,China’s car ownership is increasing year by year.Consumers pay more attention to the safety and comfort of cars when choosing cars.Among them,car noise seriously affects the ride comfort of the passenger compartment,and is also one of the criteria for judging the quality of the car.There are many reasons for car noise,and engine compartment fan noise is an indispensable part of car noise research.This paper takes the engine compartment fan as the research object,analyzes the flow field state around it to analyze the cause of the fan aerodynamic noise,and proposes control strategies to reduce the fan noise to improve the ride comfort of the passenger compartment.In this paper,the research of computational fluid dynamics and aeroacoustics is used to simulate the engine compartment of a car.Through the simulation calculation of the steady state and unsteady state of the fan,the complex flow of the gas around the fan is analyzed,especially the distribution and development of the vortex at the rear and the tip of the fan.At the same time,the FW-H equation of the far-field and the direct calculation of the near-field method are used to analyze the noise spectrum of the fan.The main research contents are as follows:Firstly,in this paper,the numerical simulation of single fan is carried out.The flow of gas around the fan is studied by analyzing the flow field information such as pressure and velocity to study the cause of the fan’s aerodynamic noise.Subsequently,a number of near-field and far-field noise monitoring points are established,and the pressure pulsation and sound pressure level are obtained,and the aerodynamic noise characteristics of the fan are further analyzed to provide a theoretical basis for the following noise reduction measures.Secondly,this paper analyzes the influence parameters of fan aerodynamic noise,and proposes control strategies according to the cause of fan aerodynamic noise,which areunequal pitch blade fan,non-smooth surface fan and bionic shark fin fan.All three control strategies have achieved good noise reduction.Thirdly,this paper studies the automotive cooling system and simulates the dual fan system with heat dissipating components.It is concluded that the noise value of the dual fan system simulation at the same monitoring point is greater than the noise value of the single fan simulation,indicating that in the dual fan system,The mutual interference between the two fans and the presence of components such as radiators and condensers have a certain influence on the aerodynamic noise of the fan.At the same time,the paper also simulates the internal flow field of the engine compartment of the vehicle,and compares the distribution of speed and temperature in the cabin before and after fan noise optimization,verify the heat dissipation characteristics of low noise fans.Finally,summarize the main work of this paper,analyze the advantages and disadvantages of the current method,and propose new direction for future research.