Evaluating flow-added damping on a hydrofoil by combining vibro-acoustics and doublet-lattice panel analyses

Abstract

Hydroelectric turbine designers need to know the damping coefficient of a turbine blade to assess its longevity. Damping is difficult to simulate numerically. Current flow-added damping evaluation methods involve solving Reynolds-averaged Navier-Stokes simulations, which are numerically expensive and complex. This paper presents a new, simple and fast method to evaluate the added damping coefficient of a standalone and straight hydrofoil using NASTRAN's multiple modules. Using the vacuum and resting fluid natural frequencies, a proportionality matrix is implemented into NASTRAN's flutter solution using the added virtual mass incremental factor to evaluate the added damping adequately. The methodology is validated against experimental and numerical data from previously published articles and presents good agreement with existing results.