Reduced order modelling of thickness effects on a cantilevered hydrofoil in homogeneous isotropic turbulence

Abstract

The response of a cantilevered hydrofoil excited by honeycomb-generated turbulence is studied with a reduced order analytical model that considers the thickness effects of NACA sections. This is achieved by extending a gust response model of the unsteady lift to include realistic 2D sections instead of using a flat plate assumption. The general chordwise thickness profiles are included in the model using the generalized Joukowski transformation. The problem is cast into a constrained optimization problem which is solved with the use of the Lagrange multiplier method. The frequency response function (FRF) of NACA sections with the same maximum thickness to chord ratio but with different leading-edge thickness profiles are calculated to investigate the effect of the hydrofoil leading edge thickness on the high frequency response. This FRF is combined with the Uncorrelated Wall Plane Wave (UWPW) technique to simulate the pressure jump amplitude on the hydrofoil due to the turbulence interaction which excites the hydrofoil in heaving and pitching motion according to Theodorsen’s hydroelastic theory. Finaly, the structural velocity spectra are compared with available experimental results of the turbulence ingestion and the effect of the different leading edge thickness profiles on the vibration response is demonstrated for various NACA sections.