Numerical Analysis of Structural Soundness by Sloshing Movement in an External Fuel Tank for Rotorcraft

Fuel sloshing during rapid maneuvers of an aircraft causes significant loads on internal components, which in severe circumstances may break components or pipes and cause fuel to leak out of the fuel tank. Moreover, a significant load is applied to the joints of an external fuel tank by such sloshing movements. This may affect the survivability of the crew as well as the safety of the aircraft, when the joints of the external fuel tank are damaged due to a design that does not accommodate the sloshing load. Therefore, to improve the survivability of aircraft and crew members, the design of external fuel tanks should be performed after estimating the structural soundness for the sloshing load through a numerical analysis of the fuel sloshing conditions. In this study, numerical analysis was performed for a sloshing test of an external fuel tank for rotorcraft. The ALE (Arbitrary Lagrangian–Eulerian) technique was used among the methods of FSI (fluid–structure interaction analysis) and the test conditions specified in the US. Military Specifications (MIL-DTL-27422D) were applied as the conditions for the sloshing movement. As a result of the numerical analysis, the structural soundness of the joints was estimated based on the load imposed on the joints of the external fuel tank. The effects of the sloshing movement on structural soundness were assessed using a margin of safety and the failure index. These were based on the stress to the internal components, metal fittings, and the composite container.