Development of Fuel Sloshing Evaluation Technique upon Crash Using Fluid-Structure Interaction Simulation

In the development of fuel tank systems, it is important to maintain fuel system integrity even if a car accident occurs. When a fuel tank undergoes a sudden change in velocity, the fuel starts to move and deforms the tank walls and baffle plates, and then the deformation changes the flow pattern of fuel. Because interaction of fuel with tank components is the main cause of fuel spillage upon crash, it is important to predict complex fluid-structure interaction responses at an early stage of crash safety development with a multiphysics simulation. Development of the multiphysics simulation technique was conducted stepwise by examining “fluid motion” and “tank deformation.” First, a sled test of a rigid-wall tank with observation window was conducted to evaluate the fluid motion inside the tank. A numerical model was developed based on an ALE (Arbitrary Lagrangian Eulerian) algorithm for the fluid and a Lagrangian algorithm for the structure. The fluid-structure interaction simulation uses a penalty method, and three different fluids: gas and liquid inside the tank and air outside the tank are modeled and coupled with the fuel tank components. Sled tests of actual fuel tanks were then conducted. Distribution of tank shell residual deformation was measured and compared with the simulation. The simulation accurately reproduced bulging and contraction deformation of the tank due to sloshing of fuel and negative pressure induced by an increase in the tank volume.