Abstract Flow-induced acoustic resonances in closed tandem side branches with large branch diameter are investigated experimentally. The diameters of the main pipe and branches are 305 mm and 64 mm, respectively. Three single branches with different lengths, L/d = 5.86–8.52, are investigated. The first and second hydrodynamic modes are excited at Strouhal numbers close to 0.4 and 0.8, respectively. The normalized pulsation amplitude of a certain mode decreases in branch length. For tandem branches, the resonances are rarely affected by the distance in the investigated range of Lt/D = 3.28–9.84. The branch number has no effects on dominant frequencies, but the critical velocity increases in branch number. In the delayed regions, the amplitudes in tandem branches are enhanced remarkably due to change in resonance mode. The maximum amplitudes excited by the first acoustic mode in the tandem branches, which are much higher than that in the single branch, are all in delay regions and close.

中文翻译：

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大直径封闭串联侧支流致声共振

摘要 实验研究了大分支直径的封闭串联侧分支中的流致声共振。主管和支管的直径分别为 305 毫米和 64 毫米。研究了三个不同长度的单枝，L/d = 5.86–8.52。第一和第二流体动力学模式分别在接近 0.4 和 0.8 的 Strouhal 数下被激发。某一模式的归一化脉动幅度在分支长度上减小。对于串联分支，共振很少受 Lt/D = 3.28-9.84 研究范围内的距离影响。分支数对主频率没有影响，但临界速度随着分支数的增加而增加。在延迟区，由于谐振模式的变化，串联支路的振幅显着增强。