A 3D finite element （FE） model for the Sutong cable-stayed bridge （SCB） is established based on ANSYS. The dynamic characteristics of the bridge are analyzed using a subspace iteration method. Based on recorded wi...A 3D finite element （FE） model for the Sutong cable-stayed bridge （SCB） is established based on ANSYS. The dynamic characteristics of the bridge are analyzed using a subspace iteration method. Based on recorded wind data, the measured spectra expression is presented using the nonlinear least-squares regression method. Turbulent winds at the bridge site are simulated based on the spectral representation method and the FFT technique. The influence of some key structural parameters and measures on the dynamic characteristics of the bridge are investigated. These parameters include dead load intensity, as well as vertical, lateral and torsional stiffness of the steel box girder. In addition, the influence of elastic stiffness of the connection device employed between the towers and the girder on the vibration mode of the steel box girder is investigated. The analysis shows that all of the vertical, lateral and torsional buffeting displacement responses reduce gradually as the dead load intensity increases. The dynamic characteristics and the structural buffeting displacement response of the SCB are only slightly affected by the vertical and torsional stiffness of the steel box girder, and the lateral and torsional buffeting displacement responses reduce gradually as the lateral stiffness increases. These results provide a reference for dynamic analysis and design of super-long-span cable-stayed bridges.展开更多
[目的]旨在有效抑制螺旋桨空化噪声,研究螺旋桨空化噪声特性及空化发声机理。[方法]基于大涡模拟(LES)与可渗透的FW-H(PFW-H)方程远场解相结合的方法,对PPTC(Potsdam Propeller Test Case)螺旋桨空化流场和声场进行高精度仿真,重点研究...[目的]旨在有效抑制螺旋桨空化噪声,研究螺旋桨空化噪声特性及空化发声机理。[方法]基于大涡模拟(LES)与可渗透的FW-H(PFW-H)方程远场解相结合的方法,对PPTC(Potsdam Propeller Test Case)螺旋桨空化流场和声场进行高精度仿真,重点研究空化对远场噪声频谱分布特性的影响及其发声机制。[结果]模拟的水动力场结果与试验数据吻合较好。研究发现,螺旋桨周围片空化(SC)和梢涡空化(TVC)的演变过程均存在显著的周期性特征,均贡献了高强度的主频噪声。其中,片空化的初生和溃灭演变过程伴随着高强度的瞬时空化体积变化,导致高频宽带噪声加剧;梢涡空化演变时出现体积回弹行为,诱发了高强度的连续声压脉动,导致在高于主频的频率处产生显著的噪声峰值。[结论]研究结果可为工程中螺旋桨空化噪声控制策略的提出和实现提供理论依据。展开更多
基金The National Science Foundation of China under Grant No.51378111the Program for New Century Excellent Talents in University of Ministry of Education of China under Grant No.NCET-13-0128+2 种基金the Fok Ying-Tong Education Foundation for Young Teachersin the Higher Education Institutions of China under Grant No.142007the Fundamental Research Funds for the Central Universities under Grant No.2242012R30002the Open Fund of Jiangsu Key Laboratory of Environmental Impact and Structural Safety in Engineering under Grant No.JSKL2011YB02
文摘A 3D finite element （FE） model for the Sutong cable-stayed bridge （SCB） is established based on ANSYS. The dynamic characteristics of the bridge are analyzed using a subspace iteration method. Based on recorded wind data, the measured spectra expression is presented using the nonlinear least-squares regression method. Turbulent winds at the bridge site are simulated based on the spectral representation method and the FFT technique. The influence of some key structural parameters and measures on the dynamic characteristics of the bridge are investigated. These parameters include dead load intensity, as well as vertical, lateral and torsional stiffness of the steel box girder. In addition, the influence of elastic stiffness of the connection device employed between the towers and the girder on the vibration mode of the steel box girder is investigated. The analysis shows that all of the vertical, lateral and torsional buffeting displacement responses reduce gradually as the dead load intensity increases. The dynamic characteristics and the structural buffeting displacement response of the SCB are only slightly affected by the vertical and torsional stiffness of the steel box girder, and the lateral and torsional buffeting displacement responses reduce gradually as the lateral stiffness increases. These results provide a reference for dynamic analysis and design of super-long-span cable-stayed bridges.
文摘[目的]旨在有效抑制螺旋桨空化噪声,研究螺旋桨空化噪声特性及空化发声机理。[方法]基于大涡模拟(LES)与可渗透的FW-H(PFW-H)方程远场解相结合的方法,对PPTC(Potsdam Propeller Test Case)螺旋桨空化流场和声场进行高精度仿真,重点研究空化对远场噪声频谱分布特性的影响及其发声机制。[结果]模拟的水动力场结果与试验数据吻合较好。研究发现,螺旋桨周围片空化(SC)和梢涡空化(TVC)的演变过程均存在显著的周期性特征,均贡献了高强度的主频噪声。其中,片空化的初生和溃灭演变过程伴随着高强度的瞬时空化体积变化,导致高频宽带噪声加剧;梢涡空化演变时出现体积回弹行为,诱发了高强度的连续声压脉动,导致在高于主频的频率处产生显著的噪声峰值。[结论]研究结果可为工程中螺旋桨空化噪声控制策略的提出和实现提供理论依据。
