Experimental and Numerical Analysis of a Coupled Fluid-Structure Subjected to Dynamic Acceleration

The present paper deals with a numerical and experimental study carried out on a coupled fluid/structure system subjected to an imposed dynamic acceleration. The coupled system is an clamped/free elastic cylinder surrounded by a heavy, incompressible fluid, contained in a concentric rigid tank, with a fluid free surface. The whole system is subjected to a transverse imposed motion, characterized by a short time duration (∼ 10 ms) and a large acceleration amplitude (∼ 400 m/s²). The principle of the study lies on both an experimental and numerical approach of the problem. This analysis is carried out in order to better understand the dynamic of the coupled system, with industrial application related to the design of embarked naval propulsion nuclear structure. From the numerical point of view, several approaches of the coupled problem are proposed: linear and non linear model are exposed, and various numerical techniques are developed. Strong coupling techniques based on finite element or boundary element are coupled to solve the linear model. Weak coupling techniques are developed to solve the non linear problem. In such technique, the numerical resolution is based on a finite volume method for the fluid problem and finite element method for the structure problem. The fluid and structure problems can be coupled with a staggered explicit or implicit algorithm. From the experimental point of view, a experimental system is designed on a shock table. Structural data (such as displacement, acceleration) are recorded with accelerometers and displacement sensors, fluid data (such as pressure and free surface motion) are recorded with pressure gauge and high-speed numerical camera.