Reduction of Drillship’s Moonpool Drag during Transit

2015 ◽  
Author(s):  
Hye Son ◽  
Kyung Pak ◽  
Suhyung Kim ◽  
Booki Kim
Keyword(s):  
Drag Reduction ◽  
Fuel Consumption ◽  
Experimental Methods ◽  
Model Tests ◽  
Total Resistance ◽  
Ship Model ◽  
Lower Fuel Consumption ◽  
Transit Speed ◽  
In Transit ◽  
Excessive Water

Due to unrestricted ocean operations of a drillship, the importance of its transit speed is increasing in the viewpoint of reducing the downtime of offshore operations to a minimum. The open moonpool in a drillship induces additional drag when the ship is in transit. As an unfavorable moonpool design may cause the excessive drag, various ways to reduce the drag have been studied in theoretical and experimental methods. In this paper, an efficient way to reduce the drag due to moonpool and consequently increase the transit speed has been proposed. The reduction of moonpool drag has been focused as the moonpool drag is around 30% of total resistance of the drillship. A simple and efficient shape to mitigate excessive water motion inside the moonpool during drillship's transit is developed and verified through a series of model tests at SSMB (Samsung Ship Model Basin). Based on the observation during the model tests, it is found that a remarkable drag reduction can be achieved by the devised moonpool shape. Thus, it is concluded that more economical operation of a drillship such as the lower fuel consumption and increase of working time can be expected.

Light-Weight Tire Concept

1996 ◽  
Vol 24 (2) ◽  
pp. 119-131
Author(s):  
F. Lux ◽  
H. Stumpf
Keyword(s):  
Fuel Consumption ◽  
Automobile Industry ◽  
Rolling Resistance ◽  
Performance Standards ◽  
Light Weight ◽  
Production Methods ◽  
Lower Fuel Consumption ◽  
Material Resources ◽  
The Past ◽  
Tire Production

Abstract Current demands by the consumer, the automobile industry, and the environment have determined the basis of this investigation. In the past, the requirements—ever faster, ever sportier—were accepted as decisive parameters for the development of our study. In the future, rational and safety-related tire characteristics as well as environmental consciousness will increase, whereas purely performance-related parameters will diminish in their importance. Through our light-weight tire project, we have paved the way for future tire generations. The first priority is the minimal use of material resources; this means a reduction of materials and energy in tire production by using advanced design and production methods without sacrificing performance standards. This benefits the consumer—the final judge of all of our activities—by considerably reducing the rolling resistance, leading to lower fuel consumption. Further design targets include the improvement of rolling behavior and increased comfort by reducing tire weight, and therefore a reduction in unsprung masses on the vehicle.

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.

Performance Improvements in Cooker-Top Gas Burners for Small Aspect Ratio Changes

2017 ◽  
Vol 9 (4) ◽  
Author(s):  
Robson L. Silva ◽  
Bruno V. Sant′Ana ◽  
José R. Patelli ◽  
Marcelo M. Vieira
Keyword(s):  
Energy Conversion ◽  
Fuel Consumption ◽  
Conversion Efficiency ◽  
Minimum Energy ◽  
Energy Conversion Efficiency ◽  
Energy Performance ◽  
Operating Conditions ◽  
Lower Fuel Consumption ◽  
Performance Improvements ◽  
Aspect Ratios

This paper aims to identify performance improvements in cooker-top gas burners for changes in its original geometry, with aspect ratios (ARs) ranging from 0.25 to 0.56 and from 0.28 to 0.64. It operates on liquefied petroleum gas (LPG) and five thermal power (TP) levels. Considering the large number of cooker-top burners currently being used, even slight improvements in thermal performance resulting from a better design and recommended operating condition will lead to a significant reduction of energy consumption and costs. Appropriate instrumentation was used to carry out the measurements and methodology applied was based on regulations from INMETRO (CONPET program for energy conversion efficiency in cook top and kilns), ABNT (Brazilian Technical Standards Normative) and ANP—National Agency of Petroleum, Natural Gas (NG) and Biofuels. The results allow subsidizing recommendations to minimum energy performance standards (MEPS) for residential use, providing also higher energy conversion efficiency and/or lower fuel consumption. Main conclusions are: (i) Smaller aspect ratios result in the same heating capacity and higher efficiency; (ii) higher aspect ratios (original burners) are fuel consuming and inefficient; (iii) operating conditions set on intermediate are lower fuel consumption without significant differences in temperature increases; (iv) Reynolds number lower than 500 provides higher efficiencies.

Experimental Investigation of Roughness Effect on Ship Resistance Using Flat Plate and Model Towing Tests

2017 ◽  
Vol 61 (02) ◽  
pp. 75-90
Author(s):  
Evangelia D. Kiosidou ◽  
Dimitrios E. Liarokapis ◽  
Georgios D. Tzabiras ◽  
Dimitrios I. Pantelis
Keyword(s):  
Flat Plate ◽  
Resistance Coefficient ◽  
Extrapolation Method ◽  
Total Resistance ◽  
Roughness Effect ◽  
Towing Tank ◽  
Ship Model ◽  
Rough Model ◽  
Smooth Model ◽  
Flow Stimulation

Towing tests on a thin flat plate of 3-mm thickness and on a ship model in smooth and rough condition were performed and extrapolation to ship scale was attempted. A newly designed experimental setup was constructed for the examination of the thin plate. The experiments on smooth flat plate included examination of a series of trip wires for flow stimulation, among which the optimum was 1.3 mm. In rough condition, the plate was covered with sandpapers of 40 and 80 grit. Both calculated roughness functions exhibited Nikuradse behavior, verifying the validity of the experiments. The equivalent sand roughness height was 1.7 times the average sandpaper roughness, as calculated by the Schlichting diagram for sand-roughened plates. Both roughness functions indicated transitionally rough regime, except for the last two data of the rougher sandpaper that lay on the fully rough regime. The results were extrapolated to ship scale using Granville method. Extrapolation of smooth model results in ship scale revealed that the traditional Froude method predicts higher resistance coefficient compared to the International Towing Tank Conference (ITTC) 78 method. Rough model results were extrapolated to ship scale by applying a newly proposed extrapolation method, using Schlichting resistance formula for rough plates as the friction correlation line, according to Froude method and for two length scales, namely the plate and ship length. The two versions of the proposed extrapolation method provided an upper and lower limit for the predicted rough hull total resistance coefficient.

Studies on Resonant Water Motion Between a Ship and a Fixed Terminal in Shallow Water

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Trygve Kristiansen ◽  
Odd M. Faltinsen
Keyword(s):  
Shallow Water ◽  
Vertical Wall ◽  
Model Tests ◽  
Ship Model ◽  
Wave Flume ◽  
Wave Elevation ◽  
Resonant Behavior ◽  
Liquid Natural Gas ◽  
Sharp Corners ◽  
Hydrodynamical Problem

This work focuses on the hydrodynamical problem of a Liquid Natural Gas (LNG) carrier near a Gravity Based Structure (GBS) -type offshore terminal subject to incoming waves in medium deep to shallow water conditions. The work is restricted to 2D, and the ship is restrained from moving. The resonant behavior of the fluid in the gap between the ship and the terminal is investigated. The problem is investigated by means of a numerical model and model tests. Potential theory is assumed, and a linear as well as a nonlinear time-domain numerical wavetank based on a boundary element method with a mixed Eulerian–Lagrangian approach is implemented for this purpose. Model tests (near 2D) of a midship section near a vertical wall are carried out in a 26.5m long and 0.595m wide wave flume in model scale 1:70. In full scale the ship beam is 45m and the ship draft is 12m. The ship model is constructed in such a way as to avoid flow separation, i.e., no sharp corners. Several parameters are varied: water depth, wave period, and wave steepness. Wave elevation is measured at 12 locations.

scholarly journals Ground Effect Aerodynamics of Race Cars

2006 ◽  
Vol 59 (1) ◽  
pp. 33-49 ◽  
Author(s):  
Xin Zhang ◽  
Willem Toet ◽  
Jonathan Zerihan
Keyword(s):  
Numerical Modeling ◽  
Drag Reduction ◽  
Ground Effect ◽  
Vital Role ◽  
Review Article ◽  
Model Tests ◽  
Force Enhancement ◽  
Rear Wing ◽  
Physical Features ◽  
Race Cars

We review the progress made during the last 30years on ground effect aerodynamics associated with race cars, in particular open wheel race cars. Ground effect aerodynamics of race cars is concerned with generating downforce, principally via low pressure on the surfaces nearest to the ground. The “ground effect” parts of an open wheeled car’s aerodynamics are the most aerodynamically efficient and contribute less drag than that associated with, for example, an upper rear wing. While drag reduction is an important part of the research, downforce generation plays a greater role in lap time reduction. Aerodynamics plays a vital role in determining speed and acceleration (including longitudinal acceleration but principally cornering acceleration), and thus performance. Attention is paid to wings and diffusers in ground effect and wheel aerodynamics. For the wings and diffusers in ground effect, major physical features are identified and force regimes classified, including the phenomena of downforce enhancement, maximum downforce, and downforce reduction. In particular the role played by force enhancement edge vortices is demonstrated. Apart from model tests, advances and problems in numerical modeling of ground effect aerodynamics are also reviewed and discussed. This review article cites 89 references.

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