An Experimental Study on the Dynamic Behavior of a Marine Riser

J. Ocean Eng. Technol. 1988;2(1):46-58.

석유 시추보호관의 운동특성에 관한 실험적 고찰

김용철,이판묵,홍사영

영남대학교 정밀기계과,한국기계연구원 대덕선박분소,한국기계연구원 대덕선박분소

Keywords: marine riser, geometric nonlinearity, vortex shedding, jump phenomena

핵심용어: 석유 시추보호관, 기하학적 비선형성, 보오텍스, 점프현상

Abstract

The experimental investigations on the motion characteristics of a marine riser both in air and water were performed. The static deflections and natural frequencies of the riser in air including the effect of static offset, were obtained from the experiment. These results were compared with those of theoretical prediction by using a simple asymptotic formula. In order to investigate the nonlinear motion characteristics of the riser subject to nonlinear viscous drag and large displacement, the forced oscillation tests both in air and water were performed. In the forced oscillation tests in air, it was found that the transverse motion due to geometrical nonlinearity grows when the amplitude of in-line oscillation exceeds a certain critical value, say, order of 1-2 diameters. The planar motions of the riser in water due to vortex shedding and the geometrical nonlinearity were described. Some of these results were also compared with those of theoretical analysis, which uses a numerical perturbation technique based on the derived linear asymptotic solutions, and found to be generally in good agreement.