Suppression of vortex-induced vibration of a rigid cylinder using flexible shrouding

Abstract

Experimental investigations were conducted to address the reduction of vortex-induced vibration (VIV) and mean drag coefficient (Cd mean) acting on the oscillating cylinder fitted with a shroud of various parameters. The effectiveness of the shrouds in suppressing the VIV of a short rigid cylinder was investigated by varying the mesh size (B) and mesh thickness (H). The experiments were performed in water flume in NAHRIM and data analysis of Cross-Flow (CF) and In-Line (IL) vibration amplitudes, IL and CF frequencies, mean drag coefficient responses were carried out. Calculation of the laminar boundary layer thickness around a circular cylinder was carried out as a benchmark in deciding the thickness of the mesh. The effect of mesh size and mesh thickness of shrouds was also addressed in this article. From the results obtained, it can be observed that the shroud with mesh size B = 0.2D and mesh thickness H = 0.03D achieved an optimum condition where it was able to suppress the amplitude without increasing Cd mean, with 76.62% of amplitude reduction and 48.40% of Cd mean reduction.