圆形封闭旁支管流致声共振实验研究

旁支管流致声共振是由特定结构下流场和声场相互作用的结果。本文针对圆形封闭旁支管结构的声共振特征展开实验，研究了旁支管高度和主管道流速对旁支管声共振现象的影响，获得了压力脉动特征和声共振发生区域。实验研究的5种旁支管高度（H/d）为6、8、10、12和14，实验雷诺数Re=3.24×10⁴～2.89×10⁵，马赫数Ma=0.029～0.26。研究结果表明：随着流速的增加，声共振频率会出现频率锁定现象；随着旁支管高度的增加，同阶声模态对应的主控频率降低，共振工况声压幅值降低，声模态转变点对应的流速减小，实验流速范围内声模态数增加。在本实验结构中，声共振主要发生在斯特鲁哈尔数St=0.2～0.55区域内。

Experimental Study of Flow-induced Acoustic Resonance in Cylindrical Closed Side Branch

Flow-induced acoustic resonance in closed side branch is a flow-acoustic coupling phenomenon caused by the interaction of flow and acoustic fields in special structure. The flow-induced acoustic resonance characteristic experiments were carried out on cylindrical closed side branch to study the influences of the velocity in main pipe and the height of the side branch on acoustic resonance. The range of occurrence and characteristics of pressure pulsation were analyzed. Five heights of side branches (H/d=6, 8, 10, 12, 14) are experimentally studied and the Reynolds number in the experiment is 3.24×10⁴-2.89×10⁵ while the Mach number is 0.029-0.26. It is found that the resonance frequency shows a lock-in phenomenon with the increase of velocity. As the height of the side branch increasing, the acoustic mode frequency decreases while the amplitude of the acoustic pressure shows no significant changes as the wall of the side branch approximately equals to rigid wall. In the considered structure, the acoustic resonance occurs when Strouhal number is in the range of 0.2-0.55.