Similarity studies of acoustic radiation in different media induced by mechanical excitations inside a single-layer cylindrical shell

Abstract

This paper investigated the similarities in vibration and acoustic radiation characteristics of single-layer cylindrical shells subjected to mechanical excitations in different media. Based on acoustic similarity principle, the dimensionless coefficients under the condition of equal similarity numbers were derived using the dimensional theory, and the acoustic similarity conditions of cylindrical shells in water and air were given. In addition, the similarity of vibration and acoustic radiation in different media was verified through numerical simulations. The results show that the predictions of vibration and acoustic radiation from the results obtained in air were in good agreement with the results in water. Notably, in the low frequency bands, the predicted radiated sound power level and sound pressure level directivity curves exhibited significant overlap with the results in water. Although deviations were observed at higher frequencies due to the effects of acoustic wave fluctuations and fluid medium properties, these discrepancies were minor, and the numerical results remained consistent with the established similarity relationships. Furthermore, an examination of stiffened cylindrical shells confirmed the applicability of the proposed similarity theory to more complex thin shell structures. Experimental validations indicate that this method has certain applicability. However, the experimental results and numerical prediction results have discrepancies in some frequency bands.