Underwater acoustic field and pressure fluctuation on ship hull due to unsteady propeller sheet cavitation

Scattering effect of submarine hull on propeller non-cavitation noise

“…(7) can be updated explicitly at each time step. As Kehr et al [16] pointed out that, all the retard-time terms in Eq. (7) can be obtained directly from a Fourier series during the process of iterations, then…”

“…It can be easily used to calculate the scattering of multi-frequency waves from underwater obstacles with an arbitrary geometry. Based on above iteration method, Kehr and Kao were the first to predict the propeller noise induced by unsteady sheet cavitation in time domain with acoustic analogy method, taking into account reflecting effect of free surface and scattering effect of ship hull on propeller noise [16]. Considering the scattering effect from the ship hull, the total amplitude of the acoustic field induced by unsteady sheet cavitation is about twice the amplitude radiated directly from the propeller.…”

Numerical investigation of marine propeller Underwater Radiated Noise using acoustic analogy part 1: The influence of grid resolution

“…The acoustic waves directly generated by the marine propeller interferes with the scattered pressure from the hull and cause change in near and far-field noise predictions. Since the 1980s, different numerical methods and solution methodologies have been developed to compute the scattering of acoustic waves from different objects (Kehr and Kao, 2011). For this reason, Kehr and Kao (2011) developed a numerical method to predict the underwater acoustic field and pressure fluctuation on a ship hull in the presence of unsteady propeller sheet cavitation by using linear wave equation.…”

Cavitation Erosion of NiTi Composite Coating Deposited by Atmospheric Plasma Spraying

“…Cavitation erosion is caused by the internal pressure change of the liquid, which causes the dissolved gas in the liquid to nucleate, grow and collapse, and the cavitation collapse process will form a huge stress pulse, which will cause the surface damage of the material on the metal surface (1) . Cavitation is widely present in various types of hydraulic machinery, such as the propellers of ship, the cylinder liner, which will lead to premature component failure and even major accidents, resulting in heavy economic losses (2,3) . Cavitation erosion is a complex process.…”