With the increase in car ownership,traffic noise pollution has increased considerably and is one of the most severe types of noise pollution that affects living standards.Noise reduction by sound barriers is a common ...With the increase in car ownership,traffic noise pollution has increased considerably and is one of the most severe types of noise pollution that affects living standards.Noise reduction by sound barriers is a common protective measure used in this country and abroad.The acoustic performance of a sound barrier is highly dependent on its shape and material.In this paper,a semianalytical meshless Burton-Miller‐type singular boundary method is proposed to analyze the acoustic performance of various shapes of sound barriers,and the distribution of sound‐absorbing materials on the surface of sound barriers is optimized by combining a solid isotropic material with a penalization method.The acoustic effect of the sound‐absorbing material is simplified as the acoustical impedance boundary condition.The objective of optimization is to minimize the sound pressure in a given reference plane.The volume of the sound‐absorbing material is used as a constraint.The density of the nodes covered with the sound‐absorbing material is used as the design variable.The method of moving asymptotes was used to update the design variables.This model completely avoids the mesh discretization process in the finite element method and requires only boundary nodes.In addition,the approach also does not require the singular integral calculation in the boundary element method.The method is illustrated and validated using numerical examples to demonstrate its accuracy and efficiency.展开更多
In this paper,the flow field around NACA0015 hydrofoil is calculated under the condition of two-phase cavitating flow to provide a theoretical guidance for reducing the cavitation noise.A modified turbulence model cou...In this paper,the flow field around NACA0015 hydrofoil is calculated under the condition of two-phase cavitating flow to provide a theoretical guidance for reducing the cavitation noise.A modified turbulence model coupled with the Zwart cavitation model is used to calculate the flow field.According to the computed sound source data,the dipole sound pressure distribution diagrams for the extremely short time and the complete time around the hydrofoil under different working conditions are obtained.The sound pressure distribution and the sound pressure amplitude are analyzed in detail.In addition,the field points around the hydrofoil are selected to generate the corresponding frequency response function curves,which are analyzed from the aspects of the trend,the variation and the extreme value.The results show that the dipole characteristics are gradually diminished and finally disappear with the increase of the frequency.At the frequency of the vapor volume fraction fluctuation,the noise level at the field point will have an extreme value.展开更多
基金The Natural Science Foundation of Shandong Province of China,Grant/Award Number:ZR2023YQ005The DAAD-K.C.Wong Postdoctoral Fellowships。
文摘With the increase in car ownership,traffic noise pollution has increased considerably and is one of the most severe types of noise pollution that affects living standards.Noise reduction by sound barriers is a common protective measure used in this country and abroad.The acoustic performance of a sound barrier is highly dependent on its shape and material.In this paper,a semianalytical meshless Burton-Miller‐type singular boundary method is proposed to analyze the acoustic performance of various shapes of sound barriers,and the distribution of sound‐absorbing materials on the surface of sound barriers is optimized by combining a solid isotropic material with a penalization method.The acoustic effect of the sound‐absorbing material is simplified as the acoustical impedance boundary condition.The objective of optimization is to minimize the sound pressure in a given reference plane.The volume of the sound‐absorbing material is used as a constraint.The density of the nodes covered with the sound‐absorbing material is used as the design variable.The method of moving asymptotes was used to update the design variables.This model completely avoids the mesh discretization process in the finite element method and requires only boundary nodes.In addition,the approach also does not require the singular integral calculation in the boundary element method.The method is illustrated and validated using numerical examples to demonstrate its accuracy and efficiency.
基金Project supported by the National Natural Science Foundation of China(Grant No.51806058)the Fundamental Research Funds for the Central Universities(Grant No.B200202170)。
文摘In this paper,the flow field around NACA0015 hydrofoil is calculated under the condition of two-phase cavitating flow to provide a theoretical guidance for reducing the cavitation noise.A modified turbulence model coupled with the Zwart cavitation model is used to calculate the flow field.According to the computed sound source data,the dipole sound pressure distribution diagrams for the extremely short time and the complete time around the hydrofoil under different working conditions are obtained.The sound pressure distribution and the sound pressure amplitude are analyzed in detail.In addition,the field points around the hydrofoil are selected to generate the corresponding frequency response function curves,which are analyzed from the aspects of the trend,the variation and the extreme value.The results show that the dipole characteristics are gradually diminished and finally disappear with the increase of the frequency.At the frequency of the vapor volume fraction fluctuation,the noise level at the field point will have an extreme value.
