Experimental Investigation of Flow Induced Rotation of Hinged Plates With Shapes to Avoid Fluttering

Abstract

This paper addresses the flow induced rotation phenomena of plates hinged to allow flow induced rotating about their vertical axis. Different transversal shape configurations are studied. The aim of this study is to simplify the fluttering problem that may occur with falling objects in water during installation of offshore devices. The investigation intent is to propose an optimized configuration for stabilizing the fluttering motion of pendulous installation method of manifolds. The experiments and dimensional analysis confirmed that natural frequency is linearly proportional to the incoming flow velocity and inversely proportional to the flat plate width, and also the equivalent harmonic angle of rotation for small oscillation angles is approximately constant in different velocities. Experiments show that the bluffer plates (plate with two stabilizers and plate with stabilizers and nose), by increasing of period of rotation and also decreasing of equivalent harmonic angle of rotation have stabilizing effect in the fluttering motion of falling objects.