For the interior sound field formed by the complex vibrating structure, an identifi- cation approach of panel acoustic contribution based on equivalent source method (ESM) was presented. The normal velocity on the s...For the interior sound field formed by the complex vibrating structure, an identifi- cation approach of panel acoustic contribution based on equivalent source method (ESM) was presented. The normal velocity on the surface of vibrating structure was first reconstructed by using interior nearfield acoustic holography based on ESM and the prediction of whole interior enclosed sound field was realized. Then the sound pressure produced by each panel at the interested field point was respectively replaced by the radiated pressure of the enclosed interior sound field which is formed by the equivalent virtual sources located near the surface of the cav- ity. Combining with the reconstructed normal surface velocity, the acoustic contribution of each panel to any position in the cavity was obtained by transforming the complex enclosed non-free field into the simple interior free field. Numerical simulations and experiments are conducted, and the influences of the number of the equivalent sources and the distance between them and the reconstructed surface have been investigated. The results show that the proposed method is easier to be implemented with the same accuracy than the traditional analysis method.展开更多
Based on the coupled boundary element method-finite element method (BEM-FEM) method and the acoustic transfer vector (ATV) technology, BEM/FEM model is proposed for a Vtype eight cylinders engine acoustic radiatio...Based on the coupled boundary element method-finite element method (BEM-FEM) method and the acoustic transfer vector (ATV) technology, BEM/FEM model is proposed for a Vtype eight cylinders engine acoustic radiation simulating analysis under semi-anechoic condition. Acoustic radiation power, field points sound pressure level and panel contributions are calculated by acoustic radiation response analysis. Additionally, based on the engine acoustic performance, different acoustic behaviors of engine are studied by changing engine materials, oil pan structures as well as geometry parameters. The acoustic performance of this engine is predicted and the influence of material, structural and geometry parameters on engine radiated noise are generalized. The principle will guide the design and optimization of the engine prototype in further work.展开更多
Reducing the radiated noise of a gearbox is a difficult problem in aviation,navigation,machinery,and other fields.Structural improvement is the main means of noise reduction for a gearbox,and it is realized primarily ...Reducing the radiated noise of a gearbox is a difficult problem in aviation,navigation,machinery,and other fields.Structural improvement is the main means of noise reduction for a gearbox,and it is realized primarily through contribution analysis and structure optimization.However,these approaches have certain limitations.In this study,a low-noise design method for a gearbox that combines the two approaches is proposed,and experimental verification is performed.First,a finite element/boundary element model is established using a single-stage herringbone gearbox.Considering the vibration excitation of the gear system,the radiation noise of a single-stage gearbox is predicted based on the modal acoustic transfer vector(MATV)method.Subsequently,the maximum field point of the radiated noise is determined,and the acoustic transfer vector(ATV)analysis and modal acoustic contribution(MAC)analysis are conducted to determine the region that contributes significantly to the radiated noise of the field point.The optimization region is selected through the panel acoustic contribution(PAC)analysis.Next,to reduce the normal speed in the optimization region,topology optimization is performed.According to the topology optimization results,four different noise reduction structures are added to the gearbox,and the low-noise optimization models are established respectively.Finally,by measuring the radiated noise of the gearbox before and after optimization under a given working condition,the validity of the radiated noise prediction method and the low-noise optimization design method are verified by comparing the simulation and experimental data.A comparison of the four optimization models proves that the noise reduction effect can be achieved only by adding a noise reduction structure to the center of the density nephogram.展开更多
基金supported by the National Natural Science Foundation of China(11274087)
文摘For the interior sound field formed by the complex vibrating structure, an identifi- cation approach of panel acoustic contribution based on equivalent source method (ESM) was presented. The normal velocity on the surface of vibrating structure was first reconstructed by using interior nearfield acoustic holography based on ESM and the prediction of whole interior enclosed sound field was realized. Then the sound pressure produced by each panel at the interested field point was respectively replaced by the radiated pressure of the enclosed interior sound field which is formed by the equivalent virtual sources located near the surface of the cav- ity. Combining with the reconstructed normal surface velocity, the acoustic contribution of each panel to any position in the cavity was obtained by transforming the complex enclosed non-free field into the simple interior free field. Numerical simulations and experiments are conducted, and the influences of the number of the equivalent sources and the distance between them and the reconstructed surface have been investigated. The results show that the proposed method is easier to be implemented with the same accuracy than the traditional analysis method.
基金Supported by the Ministry level advanced research project(40402040108)
文摘Based on the coupled boundary element method-finite element method (BEM-FEM) method and the acoustic transfer vector (ATV) technology, BEM/FEM model is proposed for a Vtype eight cylinders engine acoustic radiation simulating analysis under semi-anechoic condition. Acoustic radiation power, field points sound pressure level and panel contributions are calculated by acoustic radiation response analysis. Additionally, based on the engine acoustic performance, different acoustic behaviors of engine are studied by changing engine materials, oil pan structures as well as geometry parameters. The acoustic performance of this engine is predicted and the influence of material, structural and geometry parameters on engine radiated noise are generalized. The principle will guide the design and optimization of the engine prototype in further work.
基金National Key R&D Program of China(Grant No.2018YFB2001501)Key Program of National Natural Science Foundation of China(Grant No.51535009).
文摘Reducing the radiated noise of a gearbox is a difficult problem in aviation,navigation,machinery,and other fields.Structural improvement is the main means of noise reduction for a gearbox,and it is realized primarily through contribution analysis and structure optimization.However,these approaches have certain limitations.In this study,a low-noise design method for a gearbox that combines the two approaches is proposed,and experimental verification is performed.First,a finite element/boundary element model is established using a single-stage herringbone gearbox.Considering the vibration excitation of the gear system,the radiation noise of a single-stage gearbox is predicted based on the modal acoustic transfer vector(MATV)method.Subsequently,the maximum field point of the radiated noise is determined,and the acoustic transfer vector(ATV)analysis and modal acoustic contribution(MAC)analysis are conducted to determine the region that contributes significantly to the radiated noise of the field point.The optimization region is selected through the panel acoustic contribution(PAC)analysis.Next,to reduce the normal speed in the optimization region,topology optimization is performed.According to the topology optimization results,four different noise reduction structures are added to the gearbox,and the low-noise optimization models are established respectively.Finally,by measuring the radiated noise of the gearbox before and after optimization under a given working condition,the validity of the radiated noise prediction method and the low-noise optimization design method are verified by comparing the simulation and experimental data.A comparison of the four optimization models proves that the noise reduction effect can be achieved only by adding a noise reduction structure to the center of the density nephogram.