Analysis Of Aerodynamic Noise Transmission Characteristics And Noise Optimization Of Automotive Air-conditioner Blower

The noise characteristics of new energy vehicles are different from those of traditional fuel vehicles.The aerodynamic noise generated by automotive air-conditioner blower has become more prominent due to the loss of engine noise coverage.Therefore,the optimization of aerodynamic noise reduction for automotive air-conditioner blower has become particularly important.Aiming at the problem of aerodynamic noise of a automotive air-conditioner blower,this paper analyzed the main noise source of aerodynamic noise and the noise transmission characteristics of aerodynamic noise from the perspective of experiment and simulation,and studied the flow field characteristics of automotive air-conditioner blower.By studying the flow field characteristics,sound field characteristics and structural response characteristics of automotive air-conditioner blowers,the air conditioner blower was optimized from the two perspectives of optimizing noise sources and noise transmission paths to achieve noise reduction.The coherent analysis of the measured noise and vibration signals was carried out by experimental research methods to determine the main source of aerodynamic noise of automotive air-conditioner blowers.The transmission path of aerodynamic noise propagation was determined by the test methods of noise reduction,vibration isolation,sound insulation and vibration reduction.The experimental analysis showed that the 43th-order noise generated by the impeller rotation was the main aerodynamic noise source of the automotive airconditioner blower.The transmission path of the 43-order aerodynamic noise was mainly divided into the following three parts.The 43 th order aerodynamic noise propagates outward through the inlet and outlet.The aerodynamic force generated by the rotation of the impeller acts on the impeller to transmit to the motor through the shaft system,part of which was directly transmitted outward through the motor end cover,and the other part was transmitted to the motor flange through the vibration isolator of the motor,and then passed through the motor flange and the volute,acting on the housing to cause structural vibration and radiating noise outward.The aerodynamic force generated by the rotation of the impeller acts on the plane above the impeller,causing structural vibration of the plane,and thus radiating noise outward.The flow field characteristics,sound field characteristics and structural response characteristics of automotive air-conditioner blower was analyzed by numerical simulation.The numerical simulation results were consistent with the experimental results.The results of numerical analysis showed that the impeller rotation was the main source of aerodynamic noise;the turbulent kinetic energy of the impeller hub and the blade top was large,and the vortex tongue had obvious reflow phenomenon,which increases the overall aerodynamic noise;the sound pressure level of each measuring point and 43 The peak noise error of the order noise was less than 5dB;the aerodynamic force generated by the rotation of the impeller acts on the plane above the impeller,causing structural vibration of the plane,and then radiating noise outward.The excitation force transmitted to the plane above the impeller through the outer surface of the volute was negligible.According to the structure of automotive air-conditioner blower and the characteristics of aerodynamic noise distribution,the noise reduction research of automotive air-conditioner blower was carried out from the perspective of optimizing noise source and noise transmission path.Based on the analysis of the influence mechanism of the impeller structure on aerodynamic noise,the main noise sources of the aerodynamic noise were optimized for the impeller hub profile,impeller top arc angle,and impeller blade distribution angle.The results showed that under the condition of little change in efficiency and flow rate,the sound pressure level at the optimized measuring point of the impeller hub profile was reduced by 4.2dB,and the peak of the 43 th order noise was reduced by 5.2dB;the efficiency and flow rate were not changed much.In the case,the sound pressure level at the top angle of the impeller was reduced by 2.7dB,and the peak of the 43 th order noise was reduced by 3.2dB.After the optimization of the impeller blade distribution angle,the peak value of the original 43 th order noise disappears.Below the original 43-order amplitude,the peak maximum was 5.1 dB lower than the 43-order noise.Based on the effects of the blower structure on aerodynamic noise in the test and simulation analysis,the plane above the impeller and the motor flange with a large amount of vibration displacement and deformation were optimized,the plane above the impeller was reinforced,and the motor flange was installed Location optimization.Through optimization,the maximum deformation of the plane above the impeller was reduced by 23.98%,the mean value of deformation was not changed much,the maximum deformation of the motor flange was reduced by 28.38%,and the mean value of deformation was reduced by 30%.Through experimental and simulation studies,the main sources of aerodynamic noise and the main transmission paths of aerodynamic noise were determined.The influence of impeller structure and blower structure on aerodynamic noise was studied.The structure of the airconditioning blower of the car was optimized to reduce the aerodynamic noise This has certain guiding significance for the noise reduction design of new energy vehicle air-conditioning blowers in actual production.