Experimental investigation on the suppression of vortex-induced vibration of long flexible riser by multiple control rods

2012 ◽  
Vol 30 ◽  
pp. 115-132 ◽  
Author(s):  
H. Wu ◽  
D.P. Sun ◽  
L. Lu ◽  
B. Teng ◽  
G.Q. Tang ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Flexible Riser ◽  
Multiple Control ◽  
Vortex Induced Vibration ◽  
Control Rods

Suppressing Vortex-Induced Vibrations of Long Flexible Riser by Multiple Control Rods

2010 ◽  
Author(s):  
Hao Wu ◽  
Dapeng Sun ◽  
Lin Lu ◽  
Bin Teng ◽  
Jianqiao Zhang ◽  
...  
Keyword(s):  
Passive Control ◽  
Control Method ◽  
Slenderness Ratio ◽  
Experimental Investigations ◽  
Flexible Riser ◽  
Multiple Control ◽  
Control Rod ◽  
Response Characteristics ◽  
Pitch Distance ◽  
Control Rods

Experimental investigations on a passive control method for suppressing VIV of long flexible riser are presented in this work. A riser model with L/D (slenderness ratio) of 1750 was horizontally installed on a carriage and uniform current was simulated by towing the riser using the carriage in a wave tank, which leads to the Reynolds numbers ranging from 103 to 104. Four slender control rods with diameter d = 0.25D were placed parallel to the riser at uniform angle (i.e. at 90° intervals around the riser circumference). Different pitch distances l/D = 0.813, 1 and 1.188 were considered in this work, where l is the center-to-center distance between control rod and riser model. Strain along the riser and tension were measured by Fiber Bragg Grating and tensionmeter, respectively. The experimental results indicate that the response characteristics of a riser model with multiple control rods are quite distinct from that of a bare riser. Multiple control rods can suppress VIV response significantly, and their performance is mainly dependent on the pitch distance. It is found that the spatial maximum standard deviation of strain decreases about 84% due to the existence of control rods. The optimal pitch distance is found to be l/D ≤ 1. Moreover, spectrum analysis shows that the dominate frequency increases linearly with the increasing of flow velocity, for both the bare riser and the riser with control rods, while the frequency band of the suppressed riser becomes broader compared with the bare riser. It is also observed that the tension of the riser is slightly increased due to the presence of four rods, but not sensitive to the pitch distance.

Innovative Experimental Investigation on the Influences of the Reynolds Number

2017 ◽  
Author(s):  
Jian Gu ◽  
Antonio Carlos Fernandes
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Dimensionless Parameter ◽  
Individual Effect ◽  
Vortex Induced Vibration ◽  
Industry Standards ◽  
Experimental Facilities ◽  
The Individual

The influences of Re (Reynolds number) on the response of vortex induced vibration (VIV) have been studied by previous researches, which indicate the influences should not be ignored. However, due to the limitation of experimental facilities and complexity of the cases, the explicit influence of Re on VIV is still not fully known. Meanwhile, the industry standards also do not supply design reference taking account of Re effects quantitatively. In present work, an innovative dimensionless parameter (denoted as “inertia-viscosity”) is proposed to displace the Re in the dimensionless system, in order to clarify the individual effect of Re. With this method, comparing tests are concisely carried out, and the effectiveness and feasibility are demonstrated. Through the comparing of tests, several remarkable results are obtained.

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