Experimental study on water-entry cavity and trajectory of vehicle with asymmetric nose shape

Abstract

Different nose shape can cause a significant influence on the water entry trajectory and cavity. In order to study the evolution characteristics of cavity and trajectory of asymmetric nose in the process of water entry, based on the high-speed photography technology, the low-speed water entry comparative experiments were carried out for three different cut-angle nose types of 35°, 40° and 45° under different water entry angles. Through digital image processing technology, the contour of the water entry cavity and motion attitude information of the vehicle at different times are extracted, and the law of influence of the cut angle and entry angle on the cavity and trajectory is obtained. The experimental results show that: the cut angle side of the asymmetric nose can effectively promote the expansion of the cavity, thus forming the asymmetric water entry cavity; the expansion scale of the cavity is positively related to the initial horizontal expansion speed of the cavity and the area of the section of the head; the water entry trajectory of the asymmetric head will deflect to the cut angle side; the smaller the water entry angle is, the shorter the trajectory leveling time is, and the deeper the leveling depth is However, the change of attitude angle is almost independent of the entry angle.