Natural aero-acoustic resonance of single and double flat plates was experimentally investigated. Ten single plates of six different chord-to-thickness ratios were tested for flow around single plate, and four different gap-to-thickness ratios were tested for flow around two plates in tandem. For the case of single plates, a tool for the prediction of resonant flow velocities was established using reduced velocity. For tandem plates, the acoustic response was characterized by the presence of double resonance response that is the excitation of first acoustic mode in two different ranges of flow velocities. Reduced velocity range of low-frequency resonance fits to the range of Mode1 in single plates, this is because both resonances are natural. For high-velocity resonance, a common range could hardly be identified although the increase of gap distance showed an increase in the onset reduced velocity at resonance. It is hypothesized that the first resonance of the double response is caused by normal shedding of vortices in the gap between the plates, whereas the latter resonance is due to vortices caused by the interaction of shear layers with the downstream plate. This mechanism is different than that present in case of tandem cylinders due to the difference in separation points. It was also shown that the downstream plate can serve as a duct modification that leads to the excitation of new acoustic modes that were not excited in the case of single plates.

实验研究了单平板和双平板的自然空气声共振。测试了十个具有不同弦长/厚度比的单板围绕单板的流动，并测试了四个不同的缝隙-厚度比围绕两板的流动。对于单板的情况，使用降低的速度建立了用于预测共振流速的工具。对于串联板，声学响应的特征在于存在双共振响应，即在两个不同流速范围内激发第一声学模式。低频共振的减小的速度范围适合单个板中的模式1的范围，这是因为两个共振都是自然的。对于高速共振，尽管间隙距离的增加显示了共振时起搏速度的降低，但很难确定一个共同的范围。假设双重响应的第一个共振是由板之间间隙中的涡流正常脱落引起的，而后者的共振是由于剪切层与下游板的相互作用引起的涡流引起的。由于分离点的不同，该机构与串联气缸中的机构不同。还显示出，下游板可以用作管道修改，从而导致激发新的声模，而在单板的情况下则不会被激发。假设双重响应的第一个共振是由板之间间隙中的涡流正常脱落引起的，而后者的共振是由于剪切层与下游板的相互作用引起的涡流引起的。由于分离点的不同，该机构与串联气缸中的机构不同。还显示出，下游板可以用作管道修改，从而导致激发新的声模，而在单板的情况下则不会被激发。假设双重响应的第一个共振是由板之间间隙中的涡流正常脱落引起的，而后者的共振是由于剪切层与下游板的相互作用引起的涡流引起的。由于分离点的不同，该机构与串联气缸中的机构不同。还显示出，下游板可以用作管道修改，从而导致激发新的声模，而在单板的情况下则不会被激发。