脉冲射流声场的直接计算  

Direct calculation of acoustic field in pulse jet

作　　者：张焕好[1] 陈志华[1] 姜孝海[1] 黄振贵[1] 

机构地区：[1]南京理工大学瞬态物理国家重点实验室,江苏南京210094

出　　处：《南京理工大学学报》2014年第2期228-233,共6页Journal of Nanjing University of Science and Technology

基　　金：国家自然科学基金(11272156)

摘　　要：为了探讨亚声速射流气动声场中的主要噪声源以及声波产生机理,基于大涡模拟方法与高精度加权本质无振荡混合格式,对亚声速脉冲射流初始流场的发展过程进行了数值模拟,并根据得到的动力学流场对气动声场进行了直接计算。数值结果描述了射流剪切层在KelvinHelmholtz不稳定作用下失稳卷起小涡序列以及相邻小涡间相互旋转合并现象,并发现脉冲射流场的主要声源包括由前导压缩波形成的脉动噪声源、涡合并形成的四极子声源以及涡核内因涡卷起、变形与破碎所形成的湍流混合噪声源。其中,脉动噪声源最强,而涡合并所产生的四极子声源在整个声场中占主导地位。To discuss the main sources of aeroacoustic field and generation mechanism of acoustic waves,the process of initial flow field development in a subsonic pulse jet is simulated by using the large-eddy simulation and the high-order hybrid-weight essentially non-oscillatory scheme,and the corresponding aeroacoustic field is calculated directly based on the obtained dynamics flow. The numerical results reveal the phenomena of the vortexlets rolled up due to the Kelvin-Helmholtz instability of jet shear layer and the pairing process of neighbor vortices. Calculation results also reveal that the main acoustic sources of the pulse jet include the pulse acoustic source generated by precursor compressible waves,the quadrupole source generated by the vortex pairing and the turbulent blend acoustic sources caused by rolling up,deforming and breakup of the vortexlets within the main vortex ring. The pulse acoustic source is the strongest and the quadrupole source dominates the whole acoustic field.

关 键 词：射流 剪切层 气动声学 大涡模拟 涡合并 

分 类 号：O354[理学—流体力学]