Investigation of surface thermal characteristics induced by the acceleration of a submerged vehicle

Surface thermal characteristics are significant targets for non-acoustic detection technologies of underwater vehicles. This study aims to investigate the thermal characteristics induced by underwater vehicles during acceleration. The acceleration process of the self-propelled vehicle was obtained by simulation. Experimental and simulation studies were conducted using the temperature stratification measured in an outdoor pool as the background, while also considering the presence of a cool surface skin layer of the water. A comparative analysis between experimental and simulation results shows that the position and morphology of the surface thermal characteristics are consistent, and the area error of the thermal characteristics is within 15%. The findings reveal that, during the acceleration process of the underwater vehicle, the wake can still be divided into two stages despite the increasing speed. In the initial stage, the wake is relatively weak, making it difficult to form noticeable thermal characteristics on the water surface. Additionally, the study shows that at shallower depths, the acceleration state of the vehicle can be directly inferred from the thermal characteristics on the water surface, allowing for rough localization of the acceleration position. In contrast, at greater depths, direct determination becomes more challenging.