来流作用下板表面声辐射频率的影响因素分析

Analysis of the Influencing Factors of Surface Acoustic Radiation of Plates under the Flow Action

采用Ansys Workbench 15.0自带DM模块构建来流作用下的板模型,利用MESH模块划分网格,以及System Coupling模块进行流固耦合计算,验证数值模拟的可靠性,并对影响板表面声辐射频率的因素进行分析。数值模拟与分析结果表明,在来流作用下的板模型中,板表面声辐射主要由平行于来流方向的脉动压力产生,与壁面上垂直于来流方向的脉动压力、板后的大涡、板的固有频率无关;来流作用下板表面声辐射的基频与来流作用下板振动的基频、板后空腔的基频相同,是板后大涡基频的两倍;在大涡外且不在板后空腔的流场区域内,脉动压力无基频存在;在大涡模拟已经趋于统计稳定的情况下,FW-H与LES的非同步计算可以达到和同步计算一样的效果。

Abstract: The DM subroutine of Ansys Workbench 15.0 is applied to build the plate model under the flow action, the MESH pre-processing is used to generate the grid, and the System Coupling subroutine is utilized to analyze the fluid and structure interaction. The reliability of numerical simulation is verified. Then, the influencing factors of surface acoustic radiation of plates under the flow action are analyzed. Results of the numerical simulation and analysis show that in the plate model under the flow action, plate surface’s acoustic radiation is mainly caused by the impulsive pressure of the flow parallel to the plate surface, but is independent of the impulsive pressure of the flow vertical to the plate surface, the large eddy behind the plate and the natural frequencies of the plate. The fundamental frequency of the plate surface’s acoustic radiation is the same as that of the plate’s vibration induced by the flow action. And it is equal to the fundamental frequency of the cavity behind the plate, and twice of the fundamental frequency of the eddy behind the plate. There is no fundamental frequency of impulsive pressure in the flow field out of the eddy and the cavity. When the large eddy simulation results tend to statistically stable, the synchronous simulation and non-synchronous simulation of the FW-H and LES can yield the same results.