Dynamic Positioning Thruster Near Wake Hydrodynamic Characteristics at Near Bollard Pull

The knowledge of the hydrodynamic characteristics and momentum effects of the flow of dynamic positioning (DP) thrusters are important factors in the design of structures around the DP thrusters and in improving DP system reliability. In the present study, the flow field around a DP thruster model was precisely measured in a cavitation tunnel using a two-component laser Doppler velocimetry (LDV) system. These experiments were carried out with and without a nozzle at three different axial planes up to 1.5 diameters downstream, and the results are presented here for a pitch/diameter ratio of 1.2 at near bollard pull operating conditions (J ¼ 0.4 and J ¼ 0.45). This paper shows and compares the results of the DP thruster near wake hydrodynamic and momentum characteristics when operating with and without a nozzle at two different low advance coefficient values.

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Evaluation of a Dynamic Positioning Thruster Wake Using Laser Doppler Velocimetry

23rd International Conference on Offshore Mechanics and Arctic Engineering, Volume 1, Parts A and B ◽

10.1115/omae2004-51247 ◽

2004 ◽

Cited By ~ 2

Author(s):

Said El-Lababidy ◽

Neil Bose ◽

Pengfei Liu

Keyword(s):

Laser Doppler Velocimetry ◽

Diameter Ratio ◽

Operating Conditions ◽

Laser Doppler ◽

Hydrodynamic Characteristics ◽

Dynamic Positioning ◽

Doppler Velocimetry ◽

Near Wake ◽

Ducted Propeller ◽

Cavitation Tunnel

To provide information on the wake characteristics of Dynamic Positioning (DP) thrusters when operating with and without a nozzle under varied operating conditions, experiments were done on a ducted propeller model in a cavitation tunnel. The propeller flow field was measured with a two-component Laser Doppler Velocimetry (LDV) system, up to 1.5 diameters downstream. These experiments were carried out with and without the nozzle, and the results are presented here for a pitch/diameter ratio of 1.2 and an advance coefficient of 0.4. This paper shows and compares the results of the DP thruster near wake hydrodynamic characteristics obtained by the LDV system when operating with and without a nozzle.

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Detailed Analysis of the Wake of a DP Thruster Emphasizing Comparison Between LDV and SPIV Techniques

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.2185680 ◽

2005 ◽

Vol 128 (2) ◽

pp. 81-88

Author(s):

S. El Lababidy ◽

N. Bose ◽

P. Liu ◽

F. Di Felice

Keyword(s):

Detailed Analysis ◽

Laser Doppler Velocimetry ◽

Particle Image ◽

Operating Conditions ◽

Stereoscopic Particle Image Velocimetry ◽

Hydrodynamic Characteristics ◽

Dynamic Positioning ◽

Doppler Velocimetry ◽

Image Velocimetry ◽

Variable Operating Conditions

To provide experimental data on the hydrodynamic characteristics and features of dynamic positioning (DP) thrusters under variable operating conditions, wake measurements were performed on a DP thruster model using 2D laser Doppler velocimetry (LDV) and stereoscopic particle image velocimetry (SPIV). These tests were performed with and without a nozzle and over a range of advance coefficient values including the bollard pull condition. In this paper, a detailed analysis of the hydrodynamic characteristics of the wake at a plane equal to a distance of 0.5 diameters downstream from the thruster, at advance coefficient values of 0, 0.4, and 0.45 are presented for both the LDV and SPIV measurements showing a comparison between the results of each technique. The effect of the duct and of changes in the advance coefficient values is presented in this paper.

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