Hydroelastic analysis on water entry of a constant-velocity wedge with stiffened panels

Abstract

This paper presents a hydroelastic analysis on water entry of a constant-velocity wedge with stiffened panels. Incompressible flow and the potential flow theory are considered in the present study. Through revisiting the pressure distribution around the elastic wedge based on the Wagner theory, a semi-analytical hydrodynamic impact theory is expanded to perform the hydrodynamic analysis of elastic wedges. Mode superposition method is adopted to calculate the structural response. Modal displacements of different two-dimensional (2D) sections corresponding to the cross-sectional fluid domain are obtained from the modal analysis of a three-dimensional (3D) structure. Unlike most hydroelastic studies requiring the analytical mode shapes of structures, the coupling analysis of the 2D section between the discrete mode shapes of the finite element model and the impact hydrodynamic forces is realized; and this makes the present numerical method appropriate for complex 3D structures. By integrating the general force of different sections, the governing equation for the hydroelastic analysis of a complex 3D wedge is established.The numerical scheme of the present method is verified in 2D analysis by comparing with published literature results and the decoupled result of a commercial software. Numerical results show that the present method is more accurate than hydroelastic methods based on the Wagner model, and it can predict the oscillatory response after flow separation, which is usually infeasible in hydroelastic methods based on the Wagner model. By removing the coupled terms in the governing equations, the present method can be used for structural response analysis under the decoupled condition. Then, the numerical scheme is further validated by the comparison with the decoupled result of the commercial software. Through the comparison between coupled and decoupled results of a 3D wedge, it is found that the effect of fluid-structure interaction and the oscillatory response after flow separation are important for predicting the structural responses.