A joint experimental and numerical study of fluid structure interaction on a flexible lightweight hydrofoil in partial cavitating flow

Marine engineering applications show an interest for the design of nonmetallic structures. Expected advantages are a weight reduction, a corrosion resistance, together with a decrease of the production cost. Another but very challenging point could be to take benefit of the structure flexibility to control the system performances by passive or active means. However this must be mitigate by the mechanical resistance to strong operating conditions. From an academic point of view it gives rise to fundamental questions about the coupling between lightweight flexible structures and a heavy fluid like water in a flow potentially cavitating specially at high velocity applications. The present paper deals with an original experimental and numerical program in order to analyze the hydro-elastic response of a flexible homogeneous hydrofoil in various flow conditions including cavitating flow. The approach is based on coupling industrial CFD/CSD codes including a cavitation model and original experiments performed in a cavitation tunnel on the same configuration. The hydrofoil is instrumented with strain gauges for measuring strains and stresses. The numerical method is based on a partitioned approach with a code coupling between CFX for the fluid and Mechanical for the structure. The fluid domain is solved with a finite-volume URANS method and the structure is resolved with FEM solver. It is shown the possibility for the CSD/CFD code to compute this complex flow structure problem and that the numerical results compares favorably with the experiments. Several results based on the joint approach will be presented in the paper.