Modeling and Simulation of Interior Trajectory for Torpedo Expansionary Swim-out Launching

To understand whether the expansionary tube increases the outlet speed of torpedo and how the additional resistance due to pressure difference of seawater compensation influences the speed，a interior trajectory model for torpedo expansionary swim-out launching was set up for analyzing the forces on torpedo under abnormal limitation boundary condition in the expansionary swim-out torpedo tube. Based on the torpedo’s movement in the tube in different phases, computer simulation was conducted to calculate expansionary tube induced flow losses. Comparison of the test and simulation data indicates that the outlet speed of torpedo is increased by adopting the expansionary tube, and the additional resistance due to pressure difference of seawater compensation affects the outlet speed of torpedo. This study may provide a theoretical basis for design and improvement of the swim-out launcher.