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.

scholarly journals Experimental and Theoretical Study of the Effect of Hull Roughness on Ship Resistance

2020 ◽  
pp. 1-10 ◽  
Author(s):  
Soonseok Song ◽  
Saishuai Dai ◽  
Yigit Kemal Demirel ◽  
Mehmet Atlar ◽  
Sandy Day ◽  
...  
Keyword(s):  
Flat Plate ◽  
Rough Surface ◽  
Frictional Resistance ◽  
Total Resistance ◽  
Roughness Effect ◽  
Surface Conditions ◽  
Ship Model ◽  
Ship Resistance ◽  
Scaling Procedure ◽  
Similarity Law

Hull roughness increases ship frictional resistance and, thus, results in economic and environmental penalties. Its effect has been prevalently predicted using the similarity law scaling procedure. However, this method has not yet been validated with experimental data using a model ship. This study presents an experimental investigation into the effect of roughness on ship resistance and provides a validation of the similarity law scaling, by using tank testing of a flat plate and a model ship. Both the plate and the ship were tested in smooth and rough surface conditions, respectively. For the rough surface conditions, sand grit (aluminum oxide abrasive powder) was applied on the surfaces of the flat plate and the ship model. The roughness functions of the rough surface were derived by using the results obtained from the flat plate tests. Using the roughness function and the flat plate towing test, frictional resistance was extrapolated to the length of the model ship following the similarity law scaling procedure. The total resistance of the rough ship model was first predicted using the extrapolated frictional resistance and the result of the smooth ship model, and then compared with the results from the rough ship model. The predicted total resistance coefficients for the rough ship model showed a good agreement with the measured total resistance coefficient of the rough ship model, thus proving the validity of using Granville's similarity law scaling to extrapolate the roughness effect on ship resistance. 1. Introduction Roughness of a ship's hull, which is often caused by hull fouling (Townsin 2003) and corrosion (Tezdogan & Demirel 2014), can dramatically increase the ship resistance and hence its fuel consumption and greenhouse gas emissions, as well as the cost associated with dry-docking (Schultz et al. 2011); Granville (1958; 1978). Accordingly, there have been numerous investigations into the roughness effect on ship resistance from the earliest times to the present (e.g., McEntee 1915; Hiraga 1934; Kempf 1937; Benson et al. 1938; Watanabe et al. 1969; Loeb et al. 1984; Lewkowicz & Das 1986; Lewthwaite et al. 1985; Haslbeck & Bohlander 1992; Schultz 1998; Schultz & Swain 1999; Schultz 2002; Schultz 2004; Andrewartha et al. 2010; Schultz et al. 2011; Demirel 2015; Demirel et al. 2017a; Demirel et al. 2019).

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.

Resistance of a Ship Undergoing Oscillatory Motion

2010 ◽  
Vol 54 (02) ◽  
pp. 120-132
Author(s):  
Lawrence J. Doctors ◽  
Alexander H. Day ◽  
David Clelland
Keyword(s):  
Finite Depth ◽  
Mean Value ◽  
Wave Resistance ◽  
General Effect ◽  
Towing Tank ◽  
Ship Model ◽  
Average Value ◽  
Unsteady Effects ◽  
Oscillatory Cycle ◽  
Resistance Tests

In this paper, we describe extensions to the research of Doctors et al. (Doctors, L. J., Day, A. H., and Clelland, D., 2008, Unsteady effects during resistance tests on a ship model in a towing tank, Journal of Ship Research, 52, 4, 263–273) and Day et al. (Day, A. H., Clelland, D., and Doctors, L. J., 2009, Unsteady finite-depth effects during resistance tests in a towing tank, Journal of Marine Science and Technology, 14, 3, 387–397) in which the oscillations in the wave resistance during the constant-velocity phase of a towing-tank resistance test on a ship model were measured and predicted, in the cases of relatively deep and relatively shallow water. In the current study, the ship model was towed with a harmonic velocity component superimposed on the usual constant forward velocity. This work constitutes a first step in the understanding of the unsteady hydrodynamics of a racing shell (rowing boat). We show here that the unsteady wave resistance varies considerably from the traditional (steady) average value. Indeed, the wave resistance is frequently negative during part of the oscillatory cycle. However, the general effect is an increase in the temporal mean value of the wave resistance; this suggests that every effort should be made to reduce the unsteadiness of the motion. We also demonstrate that the unsteady wave-resistance theory provides an excellent prediction of the measured effects summarized here. These predictions are often within a few percent of the measured values of the resistance.

Computational Fluid Dynamics Applied to River Boat Hull Optimization

2021 ◽  
Vol 55 (5) ◽  
pp. 94-108
Author(s):  
Harlysson W. S. Maia ◽  
Said Mounsif ◽  
Jassiel V. Hernández-Fontes ◽  
Rodolfo Silva
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Computer Aided Design ◽  
Resistance Coefficient ◽  
Wave Profile ◽  
Total Resistance ◽  
Nsga Ii ◽  
Pressure Distributions ◽  
Aided Design ◽  
Geometric Variation

Abstract This paper extends the work of Maia and Said (“Analysis for Resistance Reduction of an Amazon School Boat through Hull Shape Modification Utilizing a CFD Tool,” 2019), proposing the optimization of a school boat hull using genetic algorithms and computational fluid dynamics (CDF) simulations. The study examines a school boat used for the transportation of children to schools in riverine communities of the Brazilian Amazon. The optimization was focused on reducing the hydrodynamic hull resistance by modifying the hull lines, using the NSGA-II (non-dominated sorting genetic algorithm II) algorithm in the CAD (computer aided design) CAESES environment. The objective of the study was to reduce the resistance coefficients: C wp (wave profile) and C wp trans (transverse wave profile), thus reducing the total resistance coefficient (C t) and the generated wave amplitude. Pressure distributions and flow lines were then evaluated to obtain an optimal modified hull with reduced wave emission (lower wave resistance) and, consequently, lower forward resistance. The proposed methodology resulted in a maximum reduction of 5% in the total resistance coefficient C t and in the identification of a trend of geometric variation of the hull for investigation in further studies.

Investigation of Environmental Effects of High Speed Boats

2020 ◽  
Author(s):  
Ahmet Dursun Alkan ◽  
Onur Usta ◽  
Alpay Acar ◽  
Elis Atasayan
Keyword(s):  
High Speed ◽  
Navier Stokes ◽  
Noise Prediction ◽  
Total Resistance ◽  
Test Results ◽  
Negative Effects ◽  
Towing Tank ◽  
Towing Tank Test ◽  
Tank Test ◽  
Propulsion Power

Luxury high-speed boats are increasingly being used for entertainment purposes. However, not only humans, but also animals are negatively affected by high-speed boats, and time is running out fast for people to do something about it. This study presents a review of current negative effects of high-speed boats to the environment. In this study, the flow around a benchmark planing Fridsma boat is simulated by CFD and resistance values for different non-dimensional Froude number (Fn) conditions are validated from the experimental results obtained from the literature. Using the same CFD methodology, a catamaran model in which the towing tank test results are available, is simulated for different Fn conditions and resistance values are predicted. In the CFD analysis, unsteady flow around the Fridsma hull model and catamaran model is simulated using overset meshing technique and turbulence is modeled by Reynolds Averaged Navier Stokes (RANS) with SST (Menter) k-omega turbulence model. Resistance values are compared with the experimental data and required propulsion powers are estimated for different Fn conditions. Then, total resistance of the catamaran for full-scale vessel is calculated using an extrapolation method and required propulsion power predictions are conducted. Noise prediction, corresponding to the required propulsion power are presented. In particular, the change of noise level and harmful gases released into the environment, when the speed of the vessel increases are examined and discussed. Consequently, it is believed that this study would lay an important foundation for the widespread investigation for the negative effects of the high-speed boats in the future.

ROUGHNESS EFFECT OF DIFFERENT GEOMETRIES ON MICRO GAS FLOWS BY LATTICE BOLTZMANN SIMULATION

2009 ◽  
Vol 20 (06) ◽  
pp. 953-966 ◽  
Author(s):  
CHAOFENG LIU ◽  
YUSHAN NI ◽  
YONG RAO
Keyword(s):  
Surface Roughness ◽  
Lattice Boltzmann ◽  
Experimental Studies ◽  
Resistance Coefficient ◽  
Lattice Boltzmann Model ◽  
Gas Flows ◽  
Fractal Boundary ◽  
Roughness Effects ◽  
Roughness Effect ◽  
Relative Roughness

The roughness effects of the gas flows of nitrogen and helium in microchannels with various relative roughnesses and different geometries are studied and analyzed by a lattice Boltzmann model. The shape of surface roughness is simulated to be square, sinusoidal, triangular, and fractal. Numerical computations compared with theoretical and experimental studies show that the roughness geometry is an important factor besides the relative roughness in the study of the effects of surface roughness. The fractal boundary presents a higher influence on the velocity field and the resistance coefficient than other regular boundaries at the same Knudsen number and relative roughness. In addition, the effects of rarefaction, compressibility, and roughness are strongly coupled, and the roughness effect should not be ignored in studying rarefaction and compressibility of the microchannel as the relative roughness increases.

Experimental Investigation of Turbulent Boundary Layer Over Smooth Flat Plate With Towing Tank: Attempt of Measurement of Frictional Stress

2007 ◽  
Author(s):  
Kiyoto Mori ◽  
Hiroki Imanishi ◽  
Yoshiyuki Tsuji ◽  
Masashi Kashiwagi ◽  
Masaru Inada ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Frictional Resistance ◽  
Reynolds Numbers ◽  
Sufficient Accuracy ◽  
Frictional Stress ◽  
Towing Tank ◽  
High Reynolds Numbers ◽  
Pressure Resistance ◽  
High Reynolds

The purpose of this study is to evaluate the frictional resistance with sufficient accuracy and to evaluate the drag coefficient at high Reynolds numbers. We have measured the resistance of flat plate with using a towing tank. Correcting the wave-making resistance, pressure resistance, and drag on turbulence simulator, it is found that the measured frictional resistance is smaller than the Karman-Schoenherr formula. But it agrees with the values suggested by Osaka et. al and Osterlund et. al.

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