Experimental Flutter Testing of a low mass ratio NACA-16012 Hydrofoil Model

The sharp increase in sailing speed experienced in the last decades has led yacht engineering to face issues of fluid-elastic instability deriving from the interaction of a 'light' structure with the surrounding 'heavy' fluid flow at high speed. In this context, the authors of this paper decided to undertake an experimental campaign to test a low mass- ratio hydrofoil model to investigate flutter instability in CNR-INM towing tank in Rome. The physical model is built as a segmented body to allow for a plain description of its elastic properties: this choice makes the results suitable to be used for validation of reduced-order analytical or numerical models. The model design methodology and the experimental set-up are detailed along with the testing procedure, substantially based on damping analysis, to identify the critical flutter speed. To have a first estimation of this critical speed, the authors implemented an analytical reduced-order model by representing the structure as a 2D spring-damper-mass system, and calculating the unsteady fluid loads by means of Theodorsen theory.