Abstract
Boilers and heat exchangers are widely used in various plants such as power and chemical plants. However, unexpected high level sounds are generated when these plants are operated and it becomes a serious problem. This kind of problem is called acoustic resonance. In addition, it has been considered that resonance generates when the frequency of the vortex shedding behind the tube bank coincides with the natural frequency of the duct system. However, it has also been thought of as a self-sustained tone. In general, the self-excited phenomenon arises when the exciting energy becomes greater than the dissipating energy. In this paper, in order to clarify the mechanism of the self-sustained tone experimentally, we tried to find the origin of the instability by changing the number of tube rows and acoustic damping. As a result, it was found that the self-sustained tone generates when the number of tube rows increases and the acoustic damping decreases.
