Research On Noise Analysis And Control Technology Of Vibratory Rollers

With the improvement of people’s awareness of environmental protection and the improvement of noise regulations,the noise problem of construction machinery products has received more and more attention from industry and academia.At the same time,compared with foreign products in the same industry,the noise problem has become one of the main factors restricting the development of our country’s construction machinery products.Therefore,the thesis takes a certain type of domestic single-drum vibratory roller as the research object,and carries out noise analysis and control research on the roller through theoretical analysis,numerical calculation and experimental research.The main research contents of the thesis are as follows:The hemisphere method is used to test the noise source of the roller,and the identification frequency of each noise source is determined by the frequency spectrum analysis method.Analyzing the frequency distribution of roller noise,it is determined that the main noise sources radiated from the cab and the far field are engine noise,fan noise and exhaust system noise.According to the characteristics of each noise source,it is divided into two categories: structural vibration noise and aerodynamic noise.At the same time,considering the noise reduction methods of sounds insulation and sounds absorption,noise reduction schemes are designed respectively.For structural vibration noise,through the complete machine test and analysis of the roller,the research object is determined to be the driver’s cab and a three-dimensional model is established.The structure,acoustic cavity and sound-structure coupling model analysis of the roller’s cab are carried out using finite element theory.The optimization of the cab structure provides a theoretical basis.For aerodynamic noise,the analysis found that the main sources are fan noise and exhaust system noise.a three-dimensional fan model is established for fan noise,LES and FW-H are used to study fan aerodynamic performance and noise characteristics,compare the performance of fans with uniform distribution,irregular non-uniform distribution and priority number arrangement.The results show that: compared with the uniform fan,the non-uniform structure has the effect of weakening the peak value and frequency shifting of the discrete noise;the irregular non-uniform distribution and the high common ratio priority number system arrangement can easily cause the flow field turbulence,so the common ratio is reasonable the priority number system can reduce the noise while ensuring the aerodynamic performance of the fan.For the exhaust system noise,a three-dimensional model of the muffler was established,and the flow field characteristics and noise reduction performance were analyzed by FLUENT and Virtual Lab,and the muffler structure was improved.The comparison found that the average transmission loss of the improved muffler increased by 15～20 d B.At the same time,the pressure loss is reduced and the air flow fluency is improved,which meets the optimization requirements of aerodynamic performance.For the research on sound insulation and sound absorption,through spectrum analysis,it is found that the sound-absorbing cotton has a better sound absorption effect in the whole frequency domain.Therefore,the design test verifies its noise reduction effect.The results show that the side hole of the sealed hood and the side of the shielding side have a significant noise reduction effect.At the same time,considering the thermal balance in the hood,use FLUENT for heat-fluid coupling analysis and structural optimization.The results show that the thermal balance in the hood meets the design requirements after optimization.