Study of the Trajectory Characteristics of Water Entry Vehicle with Different Preset Rudder Angle

This paper establishes a numerical method for multiphase flow calculations of high-speed oblique water entry of cross-medium vehicles based on the finite volume method, combined with the SST k-ω turbulence model, Volume of Fluid model, and overset mesh technology. The accuracy of this method has been validated through experiments. Numerical simulations were conducted for different preset rudder angles (0°, 10°, 15°), center of mass positions (0.8 m and 1.05 m from the nose), and water entry speeds (ranging from 100 m/s to 250 m/s). The study obtained the trajectory characteristics of the vehicle during high-speed oblique water entry under various influencing factors. The results indicate: The results indicate that a positive preset rudder angle significantly accelerates the attitude adjustment process of the vehicle. Larger rudder angles lead to faster deflection, shorter pitch-up time, and smaller maximum bag depth. A rearward shift of the center of mass enhances the nose-down moment caused by cavity asymmetry, prompting the vehicle to contact the cavity wall earlier and thereby improving the deflection efficiency. Under the same rudder angle and center-of-mass conditions, an increase in water-entry velocity shortens the pitch-up time and increases the instantaneous speed at the moment of pitch-up, but has minimal effect on the maximum bag depth, resulting in relatively stable trajectory characteristics.