| Because of the economic and efficiency of the claw pole alternative,it has been widely used by many passenger car companies.However,in the actual application process,the annoying whistling sound generated by it affects the user ’ s riding experience,so it is gradually being valued by the enterprise.How to improve the acoustic performance of claw pole generators has also become a hot research topic in engineering.It is an important part of this project to study the characteristics of the flow field and sound field of the claw pole generator under medium and high speed operating conditions,and then to explore how to reduce its aerodynamic noise level,which has certain practical significance.Aiming at the problem of prominent aerodynamic noise during high-speed operation of a certain type of claw pole generator,the research content of this paper mainly includes the following aspects:(1)Carry out the installation test of this type of claw pole generator.By drawing the infrasound power curve diagrams of different orders under no-load conditions,we get the 6th,9th,12 th,18th,30 th and 36 th orders as the main noise orders.Based on the sound power expression obtained by N.Curle,the sound power experimental data of 8000RPM-14000 RPM is linearly fitted.The results show that the linear fitting coefficient after the conversion of the sound power radiation intensity and the characteristic flow rate is close to 6,indicating that dipole is the main noise source type in this speed range.(2)The sound field is solved by a hybrid calculation method.The SAS-SST turbulence model is used for the flow field calculation,and the boundary element method is used for the sound field calculation.The flow field and sound field are calculated in ANSYS CFX and LMS Virtual.Lab respectively.Analyzing the acoustic field characteristics of the generator under two working conditions of 8000 RPM and12000RPM,the simulation results of each main order are in good agreement with the experimental values,which verifies the reliability of the calculation model.(3)First,analyze the main sources of noise of each order according to the pressure distribution of the different orders of the rotor.Then build an RG empirical model to optimize the order noise.Numerical simulation results show that for the RG empirical model,the main order noise has a certain optimization effect,but other orders will form new noise.The non-congruent fan blade vector composition method is used to further optimize the angle of the fan blades.The results show that each main order has a good optimization effect,and at the same time,it has a certain limit effect on the adjacent orders.The air passing through the front and rear fan blades The mass flow change does not exceed 1%,which has a small impact on the heat dissipation performance,which verifies the feasibility of using the VCM method to reduce the noise of a specific order.(4)Optimize the aerodynamic noise based on the way of grooving the claw pole root.Firstly,a certain grooving model is installed and tested to verify the optimization effect of grooving on order noise.Then,the grooving is modeled by parameterization,and the grooving parameters are selected using Latin hypercubes.A total of 18 different grooving models are established.According to the calculation results,comprehensively consider the influence of grooving on the 6,30,and 36 orders,and select the model with the best optimization effect.Finally,the flow field and the changes in the cloud diagram of the rotor surface pressure distribution of different orders are analyzed,and the internal mechanism of the influence of the groove on the order noise is obtained. |
PDF Full Text Request