Flow and thrust vectoring characteristics of underwater high-speed gas jet

When utilizing high-speed gas jet for the propulsion of underwater vehicles, complex flow phenomena such as ventilated cavitation, bubble expansion, and contraction are formed, along with corresponding complex thrust characteristics. In this paper, an experimental study was conducted on the thrust and flow field evolution characteristics of vector-deflected high-speed gas jets produced by a Laval nozzle under co-flow conditions. Under the experimental conditions of this study, the venting position of the pulsating foam tail cavity shifts with the increase in the nozzle vector angle θ. The axial component of thrust exhibits a noticeable loss as the vector angle θ increases, and its oscillation is correlated with the pressure pulsation of the tail cavity. The nozzle thrust vector angle operates within an optimal range, with the lateral force peaking at θ = 6°. Beyond this angle, the lateral force diminishes as θ progresses further. The amplitude of the lateral force is related to the vent channel, with unobstructed channels corresponding to the peak values of the lateral force. This paper can provide a reference for the design of vector jet propulsion systems for underwater vehicles. The unique phenomena and patterns of underwater vector jets revealed through experiments lay the foundation and offer insights for more in-depth mechanistic studies.