Hydroelastic Damping of Low Aspect Ratio Plates*

Motivated by the need to characterize flow-induced damping effects in rocket engine turbomachinery, this study numerically and experimentally considers the hydroelastic damping of low aspect ratio flat plates undergoing free vibration in flowing water.  An unsteady, three-dimensional vortex lattice model is coupled to a linear structural dynamic model to predict flow-induced damping as a function of reduced velocity.  Experimental investigations involving plates of various aspect ratios and thicknesses are conducted in a high-speed water tunnel to validate the numerical model.  The tests involve flow velocities well below those corresponding to hydroelastic instability, and the results from this flow regime indicate that hydroelastic damping is negligibly low and constant until a certain flow speed is achieved. Beyond this speed, hydroelastic damping is found to increase roughly linearly with increasing flow velocity.   The results can be used to refine the structural dynamic assessments of rocket engine components, such as turbopump inducer blades.