Experimental investigation on the hydro-acoustic characteristics of tandem cylinders with equal diameters

The investigation of the hydro-acoustic characteristics of tandem cylinders has a great importance because they occur in a variety of maritime applications that include submarines, offshore structures and seabed pipelines systems. Better understanding of the noise generation mechanism of tandem cylinders provides great contribution to reduce noise levels for many engineering applications. In this study, the hydro-acoustic characteristics of tandem cylinders with same diameter were experimentally investigated for five different distance ratios at Reynolds number of 1.6 × 10⁴. The diameter of the front and rear cylinders used in hydro-acoustic experiments is 0.02 m. It is observed that the main peak spectrum becomes narrower as the distance ratio increases. The width of the main peak spectrum also decreases as the flow regime transition from the reattachment regime to the separation regime. An increase in the distance ratio is found to correspond to an increase in the main peak frequency. The maximum sound pressure level is observed to attain its peak value at the critical distance ratio of 3.0. Notably, the maximum sound pressure level exhibits a substantial increase of approximately 6 dB as the distance ratio increases from 1.5 to 3.0, followed by a subsequent decrease of approximately 1 dB between the distance ratios of 3.0 and 6.0.