Flow-Induced Forces on Protruding Walls

A two-dimensional wall of variable thickness, protruding from a plane boundary, may be regarded as a basic geometrical configuration encountered in many instances of flow-induced structural vibrations and in fields of application ranging from aeronautics to hydraulic structures and machinery. The characteristics of the dynamic forces acting upon the face of the wall parallel to the boundary were studied for conditions, the effect of cavitation and the effect of forced periodic oscillations of the wall upon the rms value and the spectrum of the force fluctuations were investigated as functions of cavitation number and amplitude and frequency of oscillation. The results presented herein show how the control mechanisms for flow-induced vibrations may differ because of flow reattachment, cavitation, or wall displacement. Conclusions are drawn regarding possible fluid-dynamic and fluid-elastic excitation of structural vibrations.