scholarly journals Experimental Study of Air Layer Drag Reduction with Bottom Cavity for A Bulk Carrier Ship Model

2019 ◽  
Vol 33 (5) ◽  
pp. 554-562
Author(s):  
Hao Wu ◽  
Yong-peng Ou
Keyword(s):  
Experimental Study ◽  
Drag Reduction ◽  
Bulk Carrier ◽  
Ship Model ◽  
Bottom Cavity ◽  
Air Layer Drag Reduction

Experimental Study of Ship Response due to Internal Viscous Cargo Motions

2018 ◽  
Author(s):  
Virginie Baudry ◽  
Jean-Marc Rousset
Keyword(s):  
Experimental Study ◽  
Free Surface ◽  
Viscous Fluid ◽  
Fresh Water ◽  
Iron Ore ◽  
Experimental Approach ◽  
Viscous Fluids ◽  
Maritime Industry ◽  
Bulk Carrier ◽  
Ship Model

Potential liquefaction of some cargoes (Nickel ore, iron ore, ...) is a major risk for the maritime industry. The difficulties to simulate accurately the behaviour of these materials as well as their interaction with a bulk carrier model leaded us to use a non-Newtonian highly viscous fluid to model a liquefied ore. An experimental approach is presented in this paper. Roll responses of a ship model as well as details on the internal free surface behaviours are investigated for different loading conditions: solid cargo, fresh water and viscous fluids.

Drag Reduction of Recess Type Moonpool Under Vessel’s Forward Speed

2008 ◽  
Author(s):  
Hye-Jong Son ◽  
Soon-Ho Choi ◽  
Man-Hwan Kim ◽  
Seung-Myun Hwangbo
Keyword(s):  
Experimental Study ◽  
Drag Reduction ◽  
Relative Motion ◽  
Reduction Method ◽  
Flow Behavior ◽  
Forward Speed ◽  
Vertical Wells ◽  
Ship Model

Recess type moonpools are vertical wells with step frequently found in Samsung drillship. The recess moonpool was originally invented in order to move the drilling equipments without hull interferences. It was also verified that the recess type moonpool had good performance on reduction of relative motion inside the moonpool during zero speed operation. However, once the ship is under forward speed, the moonpool brings a large drag due to the oscillation of water inside the structure. In this research, a drag reduction method of the moonpool was investigated through analyzing the flow behavior inside the moonpool at the Samsung Ship Model Basin. As a result, the moonpool was modified through numerical and experimental study, which was obtained more than ten percents of drag reduction compared to normal rectangular moonpools.

Experimental Study of a Tanker Ship Squat in Shallow Water

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Mohammadreza Fathi Kazerooni ◽  
Mohammad Saeed Seif
Keyword(s):  
Experimental Study ◽  
Shallow Water ◽  
Experimental Approach ◽  
Model Tests ◽  
Ship Hull ◽  
Experimental Results ◽  
Shallow Waters ◽  
Towing Tank ◽  
Ship Model

One of the phenomena restricting the tanker navigation in shallow waters is reduction of under keel clearance in the terms of sinkage and dynamic trim that is called squatting. According to the complexity of flow around ship hull, one of the best methods to predict the ship squat is experimental approach based on model tests in the towing tank. In this study model tests for tanker ship model had been held in the towing tank and squat of the model are measured and analyzed. Based on experimental results suitable formulae for prediction of these types of ship squat in fairways are obtained.

scholarly journals Resistance reduction on trimaran ship model by biopolymer of eel slime

2015 ◽  
Vol 12 (2) ◽  
pp. 95-102
Author(s):  
Y. Yanuar ◽  
G. Gunawan ◽  
M. A. Talahatu ◽  
R. T. Indrawati ◽  
A. Jamaluddin
Keyword(s):  
Drag Reduction ◽  
Frictional Resistance ◽  
Skin Surface ◽  
Fish Skin ◽  
Total Drag ◽  
Towing Tank ◽  
Ship Model ◽  
Resistance Reduction ◽  
Towing Tank Test ◽  
Tank Test

Resistance reduction in ship becomes an important issue to be investigated. Energy consumption and its efficiency are related toward drag reduction. Drag reduction in fluid flow can be obtained by providing polymer additives, coating, surfactants, fiber and special roughness on the surface hull. Fish skin surface coated with biopolymers viscous fluid (slime) is one method in frictional resistance reduction. The aim of this is to understanding the effect of drag reduction using eel slime biopolymer in unsymmetrical trimaran ship model. The Investigation was conducted using towing tank test with variation of velocity. The dimension of trimaran model are L = 2 m, B = 0.20 m and T = 0.065 m. The ship model resistance was precisely measured by a load cell transducer. The comparison of resistance on trimaran ship model coated and uncoated by eel slime are shown on the graph as a function of the total drag coefficient and Froude number. It is discovered the trimaran ship model by eel slime has higher drag reduction compared to trimaran with no eel slime at similar displacement. The result shows the drag reduction about 11 % at Fr 0.35.

scholarly journals 710 Experimental Study on Friction Drag Reduction Effect of Flexible Tube(1)

2006 ◽  
Vol 2006 (0) ◽  
pp. _710-a_
Author(s):  
Zhigang GAO ◽  
Masatomo OHWAKI ◽  
Motoyuki ITOH ◽  
Shinji TAMANO ◽  
Kazuhiko YOKOTA
Keyword(s):  
Experimental Study ◽  
Drag Reduction ◽  
Friction Drag ◽  
Flexible Tube ◽  
Reduction Effect ◽  
Friction Drag Reduction

Air Layer on Superhydrophobic Surface for Frictional Drag Reduction

2020 ◽  
Vol 64 (02) ◽  
pp. 118-126
Author(s):  
Bradley C. Peifer ◽  
Christopher Callahan-Dudley ◽  
Simo A. Makiharju
Keyword(s):  
Drag Reduction ◽  
Superhydrophobic Surface ◽  
Energy Savings ◽  
Surface Hydrophobicity ◽  
Net Energy ◽  
Frictional Drag ◽  
Gas Flux ◽  
Still Images ◽  
Painted Surface ◽  
Air Layer Drag Reduction

We examined the feasibility of combining a superhydrophobic surface (SHS) and air layer drag reduction (ALDR) to achieve the frictional drag reduction (DR) shown achievable with traditional ALDR, but at a reduced gas flux to increase the achievable net energy savings. The effect of a commercial SHS coating on the gas flux required to maintain a stable air layer (AL) for DR was investigated and compared with that of a painted non-SHS at Reynolds numbers up to 5.1 X 106. Quantitative electrical impedance measurements and more qualitative image analysis were used to characterize surface coverage and to determine whether a stable AL was formed and maintained over the length of the model. Analysis of video and still images for both the SHS and painted surface gives clear indications that the SHS is able to maintain AL consistency at significantly lower gas flux than required on the non-SHS painted surface. Hydrophobicity of the surfaces was characterized through droplet contact angle measurements, and roughness of all the flow surfaces was measured. The results from these preliminary experiments seem to indicate that for conditions explored (up to Rex = 5.1 X 106), there is a significant decrease in the amount of gas required to establish a uniform AL (and hence presumably achieve ALDR) on the SHS when compared with a hydraulically smooth painted non-SHS.

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