Fluid Structure Interaction

Introduction

Fluid Structure Interactions play a significant role in many engineering applications and particularly in turbo machinery. Physical phenomena such as rotor-stator interactions, flow-induced vibrations of vane excited by karman vortices, precessing development of vortex rope in the draft tube, can lead to vibrations of the hydraulic machine. The prediction of fluid-structure coupling is thus necessary to design reliable, high-performance and resistant turbomachines.

Prediction of Fluid-Structure Interaction

Coupled simulations in case of complex geometry are extremely time consuming, therefore alternatives method have to be developped for hydraulic machines. Numerical and experimental investigations in the case of a rigid oscillating hydrofoil surrounded by an incompressible turbulent flow led us to develop a model to predict the fluid-structure coupling when linearized reponse of the fluid can be assumed.

Coupled Fluid-Structure Simulations

With the development of computing ressources, coupled simulations of fluid structure interaction are now realizable in simple case. Numerical simulation of von karman vortices excitation of a deformable hydrofoil are carried out with ANSYS CFX softwares. Lock-off and lock-in phenomena are investigated.

Animation

Coupled simulation of a deformable NACA 0009 excited by the Karman Vortices for lock-in conditions.

Iso-surfaces of Q criterion colored by the vorticity in the wake of the hydrofoil colored by the resulting deformation (torsion mode).