Scaled model testing for the helical strakes in reducing the vortex-induced vibrations

Abstract

The accuracy of the prediction of the suppression efficiency of the triplex helical strakes for vortex-induced vibrations (VIV) is important in the offshore industry for the risers. Towing tank tests of the 1:1 section model have been used in the study of one degree of freedom; however, this method requires a long time for both the preparation and the testing. In this study, a scaled model testing method based on the flume and the oscillating frame is proposed, which measured the oscillating amplitude and the forces for both the bare pipe and the triplex helical strakes. The scaled tests were carried out in the TU Delft, with the range of Reynolds number between 6000 and 20000. The results were compared with the real model test applied in the towing tank to evaluate the accuracy. The measured strake efficiency of the scale model test agrees with the full-scale model test, providing support for the scaled model test in reducing the vortex-induced vibrations.