Experimental study on the slamming pressure distribution of a 3D stern model entering water with pitch angles

Abstract

Accurate prediction of slamming loads on stern impact is quite difficult due to complex air effects. In this paper, the load characteristics of a three-dimensional stern model with pitch angle are studied by a drop test. The pressure distribution and impact velocity at a drop of 250–900 mm and a pitch angle of 0–15° are measured. The validity of the measurement is verified based on the repeatable analysis. The load characteristics under the pitch angle are further analyzed. The pressure near the stern shaft has complex characteristics, such as multi-peak values and high-frequency oscillation. The vibration sources of pressure are clarified, where the cavity is the main, and the support frame is the secondary. In addition, the vibration characteristics of the load are also affected by the height and pitch angle, in which the drop height has a greater effect on the high-frequency components. The influence of the pitch angle on the load characteristics is further discussed. The load peak increases 30%–60% from 0° to 15°. Finally, the influence of impact velocity and three-dimensional flow on the pressure peak is discussed. These findings reveal the law of stern load affected by pitch angle.