Characteristic Research On The Water Entry Of Slender Cylinder

The water-entry of objects is recognized as a classic hydromechanical problem. This phenomenon is more common in real life, but, the problem of cavity which from objects into water not only refer to the impacting procession, but also material of objects, condition of water and change of conditions that the movement of the objects in water. The present achievements in scientific research can’t explain the law of water entry.The thesis absorb design philosophy of equipment and method of experiment of water entry at first, design and assemble a reliable equipment of water entry experiment, and, do a series of experiment with high speed camera. The experiments describe the phenomenon of the slender cylinder’s movement in water on different conditions of water entry. The experiments use software of pictorial disposition to handle the experimental photo to get the displacement of the slender cylinder. Though calculation, it can get the velocity, deceleration and drag coefficient. By compare with the experimental data and phenomenon of water entry, exploring the internal theory.The experiment of water entry include vertical water entry and slant water entry. The experiment of vertical is the slender cylinder into water at different velocity, obtain the changing process of cavity, and though dealing with the experimental data, get the changing process of velocity and deceleration. The decline of deceleration response that the cavity can decrease the drag force of water. And, when the slender cylinder into water vertically, its trajectory will deflect, combine with the collapse of cavity, discuss the reasons of deflection. The experiment of slant is the water entry process of the slender cylinder at different slant angle, obtain the process of the cavity, though dealing with the experimental data, calculate the process of drag coefficient at different slant angle, response the drag coefficient will increase along with the angle of water entry, also, the top of drag force of water will apparent earlier. Combining with the phenomenon of experiments, the main elements which influence the drag coefficient is vertical component of the velocity. After all, making a report about the laws of water entry of the slender cylinder, prepare for the next work study the internal mechanism of the phenomenon.