Influence of Different Water Depths on Gas Jet of Underwater Scarfed Nozzle

Abstract

Thrust vector control by scarfed nozzle jet can realize attitude control and trajectory adjustment of the undersea vehicle and improve the maneuvering performance and stability of the undersea vehicle. In order to investigate the working state of the underwater scarfed nozzle, the Reynolds time-averaged Navier-Stokes(RANS) method and the volume of fluid(VOF) model were used, and simulation of the flow field characteristics and thrust characteristics of the gas jet of the scarfed nozzle under different water depth conditions was carried out. The interaction between the gas jet and the water, as well as the change in the thrust characteristics of the nozzle were analyzed. The results show that the gas bubble forms a gas pocket at the top and a conical gas channel in the near field of the nozzle after four stages of development. The edges of the gas pocket detach under the action of the shear vortex to form a gas cluster. The shape and position of the nozzle wave system vary with the water depth, and the jet boundary is limited by the gas bubble boundary. They interact with each other, leading to the unstable evolution of the jet. The influence of the jet on the wall of the flat plate is asymmetric, with the long side being more affected than the short side. At the same moment, greater water depth indicates a smaller value of the nozzle thrust and more violent fluctuation along the thrust direction. The conclusions can provide a reference for the application of underwater thrust vector nozzles.

Keywords

• scarfed nozzle
• gas jet
• flow field characteristics
• thrust characteristics