scholarly journals Comparative modeling of hull form resistance for three ocean going vessels using methodical series

2015 ◽  
Vol 4 (4) ◽  
pp. 489 ◽  
Author(s):  
Nitonye Samson ◽  
Adumene Sidum
Keyword(s):  
Reynolds Number ◽  
Frictional Resistance ◽  
Comparative Modeling ◽  
Resistance Coefficient ◽  
Container Ship ◽  
Test Technique ◽  
Hull Form ◽  
Reynolds Number Increase ◽  
Friction Line ◽  
Resistance Coefficients

This paper presents a comparative estimation of the hull form resistance for Cargo ship, Ocean-going Tug and Container ship. The research study evaluates the influences of various ship hull parameters in relations to the vessel speeds and level of turbulence (Reynolds number). The modeling was done using MATLAB software and the model test technique based on the ITTC, ATTC, Granville and Hughes friction line application. The result shows that the hull form resistances follow the same trend in the ITTC, ATTC and Granville models, while the Hughes model gave a different trend with other techniques. It further revealed that as the speed increases by 10knots, the frictional resistance coefficients decrease by 11.86% for the ITTC & Granville models, and 12.03% for the Hughes model. For Ocean-going Tug and Container Ship, the frictional resistance coefficient decrease by 12.31% for the ITTC & Granville models, and 12.14% for the Hughes model. The Reynolds number increase by 62.52% for every 10knots increase in the speed of the Cargo ship and 62.23% for every 10knots increase in the speed of the Ocean going tug and Containership. At various experimental speeds, the results showed that for every 1 knots increase in the speed of the Containership, the effective power developed increases by 9.45%. This provides a technical and analytical guide on hull form resistance trend for engineers and ship operators.

The Relationship Between Frictional Resistance and Roughness for Surfaces Smoothed by Sanding

2002 ◽  
Vol 124 (2) ◽  
pp. 492-499 ◽  
Author(s):  
Michael P. Schultz
Keyword(s):  
Reynolds Number ◽  
Frictional Resistance ◽  
Resistance Coefficient ◽  
Polished Surface ◽  
Average Height ◽  
Freestream Velocity ◽  
Number Range ◽  
Test Fixture ◽  
Plate Length ◽  
The Relationship

An experimental investigation has been carried out to document and relate the frictional resistance and roughness texture of painted surfaces smoothed by sanding. Hydrodynamic tests were carried out in a towing tank using a flat plate test fixture towed at a Reynolds number ReL range of 2.8×106−5.5×106 based on the plate length and freestream velocity. Results indicate an increase in frictional resistance coefficient CF of up to 7.3% for an unsanded, as-sprayed paint surface compared to a sanded, polished surface. Significant increases in CF were also noted on surfaces sanded with sandpaper as fine as 600-grit as compared to the polished surface. The results show that, for the present surfaces, the centerline average height Ra is sufficient to explain a large majority of the variance in the roughness function ΔU+ in this Reynolds number range.

An Experimental Study of the Viscous Resistance of a 0,564-CB Form

1979 ◽  
Vol 23 (02) ◽  
pp. 140-156
Author(s):  
P. N. Joubert ◽  
P. H. Hoffmann
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Skin Friction ◽  
Resistance Coefficient ◽  
Viscous Resistance ◽  
Local Skin ◽  
Friction Resistance ◽  
Local Skin Friction ◽  
The University ◽  
Resistance Coefficients

Wind tunnel tests were performed to determine the viscous resistance and its components for a 0.564-CB model from the BSRA Trawler Series. It was found that the sum of the pressure and skin friction resistance coefficients agreed well with the viscous resistance coefficient determined from drag balance tests. The range of Reynolds number examined was from 1.15 × 106 to 5.17 × 106. The results for the viscous resistance and its components were fitted using least-squares methods to various equations. The results were also compared with the results of previous tests done at the University of Melbourne on models of Lucy Ash-. ton and a 0.80-CB tanker. It was found that the skin friction and viscous resistance coefficients had curves of quite different position and slope. Local skin friction distribution showed noteworthy differences, especially at the stern, with high values at the keel and low values approaching the waterline.

Study on the Resistance Characteristics of Heat Metering System Based on Electric Valve

2014 ◽  
Vol 492 ◽  
pp. 507-510
Author(s):  
Dong Jun Gong ◽  
Yao Zhang ◽  
Xing Ru Li ◽  
Li De Fang ◽  
Zi Hui Wei ◽  
...  
Keyword(s):  
Pressure Difference ◽  
Theoretical Calculations ◽  
Frictional Resistance ◽  
Resistance Coefficient ◽  
Experiment System ◽  
Average Value ◽  
Parallel Pipeline ◽  
Heat Metering ◽  
The Relationship ◽  
Resistance Coefficients

Through theoretical calculations and derivation, the paper obtained the relationship between resistance coefficient and pressure difference, as well as flow rate. For the series pipeline, the flow in the series pipeline is the same, as a result, all the resistance in the series pipeline is the total resistance. For the parallel pipeline, the pressure difference is same, and the all the flow in parallel pipeline is the total flow. According to the real example, the paper identified the inlet pressure difference of the indoor system, the most unfavorable ring and the ratio frictional resistance. Based on the room heat load calculation, the paper determined the most unfavorable loop diameter of each pipe section. By calculating the resistance coefficients of the electric valve at opening, the resistance coefficients of the electric valve at closing were obtained. In the experiment system, the resistance coefficient average value when the electric valve is off was 101831.65, which is basically in line with the calculable value 10719.6, indicating that the existing parameters are much more reasonable.

scholarly journals Numerical Calculation of the Tee Local Resistance Coefficient

2015 ◽  
Vol 9 (1) ◽  
pp. 876-881 ◽  
Author(s):  
Qin Zhang ◽  
Manlai Zhang ◽  
Zhihong Zhou ◽  
Shizhong Wei
Keyword(s):  
Cfd Simulation ◽  
Flux Ratio ◽  
Frictional Resistance ◽  
Resistance Coefficient ◽  
Head Loss ◽  
Local Resistance ◽  
Local Resistance Coefficient ◽  
Tee Junction ◽  
Resistance Coefficients

The local head loss of tee could be calculated with the determination of local resistance coefficient by CFD simulation and test. Based on the mesh-independent feature identified, the flow field inner tee was numerically simulated by the standard k - ε turbulent model and SIMPLEC algorithms, which has revealed the mainstream was obliged to turn to the opposite side of tee junction, and a rise in pressure drop between upstream and downstream was caused as a result. Furthermore, the frictional resistance coefficient was calculated for eliminating the frictional head loss of model, which decreased from 0.0207 to 0.0133 when the inlet velocity increased from 1 m/s to 12 m/s. Additionally, the local resistance coefficients of tee at flow conditions were attained, and the quadratic polynomial between the local resistance coefficient and flux ratio was presented due to the influence of branch on mainstream. Through the test, the simulation result has been compared and the effectiveness of simulation has been verified.

Time Dependances of the Resistance Coefficients of Polymeric Materials

INEOS OPEN ◽  
2020 ◽  
Vol 3 ◽  
Author(s):  
A. V. Matseevich ◽  
◽  
A. A. Askadskii ◽  
Keyword(s):  
Time Dependence ◽  
Physical Mechanism ◽  
Polymeric Materials ◽  
Resistance Coefficient ◽  
Constant Stress ◽  
Time To Rupture ◽  
Structure Sensitive ◽  
Material Durability ◽  
Resistance Coefficients ◽  
Extremal Character

One of the possible approaches to the analysis of a physical mechanism of time dependence for the resistance coefficients of materials is suggested. The material durability at the constant stress is described using the Zhurkov and Gul' equations and the durability at the alternating stress—using the Bailey criterion. The low strains lead to structuring of a material that is reflected in a reduction of the structure-sensitive coefficient in these equations. This affords 20% increase in the durability. The dependence of the resistance coefficient assumes an extremal character; the maximum is observed at the time to rupture lg tr ≈ 2 (s).

Prediction of Residual Resistance Coefficient of Low-Speed Full Ships Using Hull Form Variables and Machine Learning Approaches

2020 ◽  
Vol 57 (6) ◽  
pp. 312-321
Author(s):  
Yoo-Chul Kim ◽  
Kyung-Kyu Yang ◽  
Myung-Soo Kim ◽  
Young-Yeon Lee ◽  
Kwang-Soo Kim
Keyword(s):  
Machine Learning ◽  
Resistance Coefficient ◽  
Learning Approaches ◽  
Hull Form ◽  
Residual Resistance ◽  
Low Speed

Pressure, Frictional Resistance, and Flow Characteristics of the Partially Wetted Rotating Disk

1968 ◽  
Vol 90 (2) ◽  
pp. 395-404 ◽  
Author(s):  
H. N. Ketola ◽  
J. M. McGrew
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Pressure Gradient ◽  
Flow Characteristics ◽  
Frictional Resistance ◽  
Rotating Disk ◽  
Practical Applications ◽  
Stationary Wall ◽  
Spacing Ratio ◽  
Analytical Expressions

A theory of the partially wetted rotating disk is described and experimental data presented which verify the application of this theory in practical applications. Four different flow regimes may be identified according to the value of the disk Reynolds number and the spacing ratio between the disk and stationary wall. The analytical expressions for prediction of the pressure gradient developed and the frictional resistance are uniquely determined by the disk Reynolds number, spacing ratio, and the degree of wetting of the disk.

A Study on Resistance Performance for Various Trim Conditions and Bulb Shapes on a Container Ship Under Slow Steaming

2015 ◽  
Author(s):  
Hyun-Suk Park ◽  
Dae-Won Seo ◽  
Ki-Min Han ◽  
Dae-Heon Kim ◽  
Tae-Bum Ha
Keyword(s):  
Form Factor ◽  
Prediction Method ◽  
Experimental Result ◽  
Operating Efficiency ◽  
Container Ship ◽  
Power Prediction ◽  
Hull Form ◽  
Slow Steaming ◽  
Bulbous Bow ◽  
Resistance Performance

Hull form had been unavoidably optimized for a single speed condition, normally a contract speed at design draft in the past many years due to various reasons such as limited design period, less advanced data processing capacity of a computer and so on. For this reason, for maximizing present ship’s operating efficiency, additional analysis relevant to resistance performance for slow steaming condition is newly required since the original hull form for this study also was developed about 10 years ago. In this paper, the resistance performances corresponding to various trim conditions are investigated not only for ship’s original contract speed (Fn: 0.255) but for slow speed (Fn: 0.163∼0.183) by slow steaming. Through this study, it can be accomplished to identify the optimum trim condition meeting the objectives of ship operator. Further to the trim optimization, bulbous bow shape renovation was carried out for off design condition (Fn:0.173) and both of CFD results, one is from an original bulbous bow shape, the other is from a reformed bulbous bow shape by us, are compared each other to identify the concrete reason for the improvement of resistance performance. Commercial CFD code of the STAR-CCM+ was utilized to evaluate the ship’s resistance performance on a 6,800 TEU container ship. To validate of the effectiveness of Starccm+, the experimental result of the subject hull form is referred and compared with the result from STAR-CCM+. Form factor prediction method by CFD that is based on extracting form pressure resistance component from difference of two different computational domains is presented. In this study, it is investigated to compare the form factor calculated by CFD with the model test result. This approach allows hull form designer to calculate a form factor corresponding ship’s trim variation by CFD in order to separate total resistance into wave making resistance and viscous resistance for more accurate effective power prediction.

scholarly journals Analysis of trimaran-pentamaran side hull location based on clearance and staggers with stern form variations

2018 ◽  
Vol 67 ◽  
pp. 04003
Author(s):  
Yanuar ◽  
Wiwin Sulistyawati ◽  
R. Joshua Yones ◽  
Samodero Mahardika
Keyword(s):  
Surface Area ◽  
Optimum Design ◽  
High Speed ◽  
Frictional Resistance ◽  
Experimental Tests ◽  
Hull Form ◽  
Negative Interference ◽  
Friction Resistance ◽  
Resistance Reduction ◽  
Wetted Surface Area

An optimum design of ship is to achieve the required speed with minimum power requirements. On multihull, sidehull position against to mainhull influences the friction resistance and its stability. Frictional resistance of multi-hull increases due to the addition of wetted surface area of hull, but wave making resistance can be lowered by a slender hull form. This research are experimental tests of trimaran with five Wigley hulls on a combination transom and without transom. The test varied on stagger, clearance and trim at several speeds. A ship with formation arrow tri-hull on forward was given to prove the resistance reduction due to cancellation wave which was indicated by negative interference. The influence diverse position of sidehull has shown that model non-transom (NT) stern moreover give beneficial resistance than model with transom (WT) at high speed. Similarly, in the trim conditions that NT more favorable on trim specifically for high speed depending on the position of the sidehull to the mainhull.

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