Experimental Study on the Impact Loads Acting on a Horizontal Rigid Cylinder During Vertical Water Entry

This paper experimentally studies the local and global loads acting on a rigid cylinder subjected to water wave slamming. Local loads are hereby expressed in terms of pressure on the cylindrical surface while global loads are investigated in terms of force acting on the complete cylinder. Global impact loads may be better suited for use in design processes. An experimental setup to perform vertical drop experiments to approximate wave slamming is presented and the necessary measuring equipment is described. The experimental results are firstly discussed in the time domain to understand what exactly is happening during the water entry and in what stage the maximum loads occur. The measurements learn that the time scale of the pressure and the force histories is considerably different. Secondly, the attention is focused on the peak values of the time plots. These impact pressures and impact forces are represented as function of the impact velocity. The pressure is hereby given for different positions along the circumference of the cylindrical surface. The experiments show that the impact pressure and force increase very fast with growing impact velocity, indicating that large loads accompany waves with large velocities. Wave slamming is thus an important design criterion for all kind of cylindrical structures when exposed to harsh sea conditions.