Wake Features of Moving Submerged Bodies and Motion State Inversion of Submarines

The interaction between a moving submerged body and a homogeneous/stratified fluid generates a Bernoulli hump, a Kelvin wake, and an internal wake on the water surface. The height distribution of wakes is directly related to the location and motion state of the submerged body. Thus, it is possible to retrieve kinematics information of a submarine from the images of wakes obtained by photoelectric detection equipment. In order to extract the submarine's location and velocity information effectively from the wake photoelectric images, we investigate the relationship between the motion state of moving submerged bodies and wakes in this paper. Bernoulli hump, Kelvin wake, and internal wake models are established based on potential flow theory and thin-ship approximation. We analyzed the wave crestline pattern and the energy characteristics of Kelvin wake components (divergent and transverse waves) and internal wakes at different velocities and diving depths. Finally, we propose a method for estimating the velocity of a submarine based on the wake wavelength and the diving depth inversion method based on the Fourier power spectrum of the Kelvin wake. The results obtained prove the feasibility of using photoelectric equipment to obtain wake images for use in analyzing the kinematics state of submarines, which are of guiding significance for detection and information processing in real-scale submarines.