ON THE MACRO HYDRODYNAMIC DESIGN OF HIGHLY EFFICIENT MEDIUM- SPEED CATAMARANS WITH MINIMUM RESISTANCE

2021 ◽  
Vol 154 (A3) ◽  
Author(s):  
M Haase ◽  
J Binns ◽  
G Thomas ◽  
N Bose ◽  
G Davidson ◽  
...  
Keyword(s):  
High Speed ◽  
Preliminary Design ◽  
Total Resistance ◽  
Hull Form ◽  
Transport Efficiency ◽  
New Class ◽  
Highly Efficient ◽  
Medium Speed ◽  
Resistance Curves ◽  
Minimum Resistance

A new class of fuel-efficient and environmentally friendly twin-hull vessels is currently under development. Compared to high-speed catamarans, a significant reduction in speed combined with an increase in deadweight tonnes will lead to a highly efficient medium-speed catamaran design. Recently-built conventional and high-speed ferries are compared to each other in terms of length, speed, deadweight and transport efficiency to classify the new design. The goal of this study is to find a preliminary macro design point for minimum total resistance by considering the main particulars of the catamaran vessel: block coefficient, prismatic coefficient and slenderness and separation ratios of the demihulls. Publications containing recommendations towards the optimum hull form parameters for moderate Froude numbers are reviewed and existing experimental data analysed to identify parameters for this new class of vessel. Designs with varied L/BOA-ratios and constant deck area are compared to find configurations of low total resistance for carrying a nominated deadweight at a particular speed, the associated change of the light ship weight has been taken into account. Two different model test series of catamaran models have been considered and their resistance curves agreed to each other. Recommendations are made; with the most important being the vessel should not exceed a speed of Fr = 0.35, with optimal prismatic coefficients around CP ≈ 0.5 and low transom immersion. This study presents the preliminary design of medium-speed single and twin-hull vessels for operations close to hump speed.

On The Macro Hydrodynamic Design Of Highly Efficient Medium-speed Catamarans With Minimum Resistance

2012 ◽  
Vol 154 (A3) ◽  
Keyword(s):  
High Speed ◽  
Preliminary Design ◽  
Total Resistance ◽  
Hull Form ◽  
Transport Efficiency ◽  
New Class ◽  
Highly Efficient ◽  
Medium Speed ◽  
Resistance Curves ◽  
Minimum Resistance

A new class of fuel-efficient and environmentally friendly twin-hull vessels is currently under development. Compared to high-speed catamarans, a significant reduction in speed combined with an increase in deadweight tonnes will lead to a highly efficient medium-speed catamaran design. Recently-built conventional and high-speed ferries are compared to each other in terms of length, speed, deadweight and transport efficiency to classify the new design. The goal of this study is to find a preliminary macro design point for minimum total resistance by considering the main particulars of the catamaran vessel: block coefficient, prismatic coefficient and slenderness and separation ratios of the demihulls. Publications containing recommendations towards the optimum hull form parameters for moderate Froude numbers are reviewed and existing experimental data analysed to identify parameters for this new class of vessel. Designs with varied L/BOA-ratios and constant deck area are compared to find configurations of low total resistance for carrying a nominated deadweight at a particular speed, the associated change of the light ship weight has been taken into account. Two different model test series of catamaran models have been considered and their resistance curves agreed to each other. Recommendations are made; with the most important being the vessel should not exceed a speed of Fr = 0.35, with optimal prismatic coefficients around CP ≈ 0.5 and low transom immersion. This study presents the preliminary design of medium-speed single and twin-hull vessels for operations close to hump speed.

The Design of an Eight-Oared Rowing Shell

1993 ◽  
Vol 30 (02) ◽  
pp. 84-99
Author(s):  
Carl A. Scragg ◽  
Bruce D. Nelson
Keyword(s):  
Shallow Water ◽  
High Speed ◽  
Hull Form ◽  
Model Scale ◽  
Minimum Drag ◽  
Final Design ◽  
Minimum Displacement ◽  
Resistance Curves ◽  
Hull Forms ◽  
Minimum Resistance

Rules governing the design of rowing shells do not restrict basic hull parameters. In designing a new eight-oared rowing shell for international ard Olympic competition, the authors sought a high speed, minimum drag hull form, subject only to the constraints on minimum displacement and roll stability. An investigation of optimum hull parameters using analytically determined resistance curves was made. Optimum hull parameters for both deep and shallow water racing are presented. Using the hull parameters determined for minimum resistance at racing speeds in shallow water, several new hull forms were created and analyzed in both deep and shallow water. Two promising final design candidates were proposed for model-scale testing. Results of both steady and unsteady towing tests are presented.

Filtration of Lubrication Oil in Railway Applications

2006 ◽  
Author(s):  
Stefan Schmitz ◽  
Ru¨diger Lennartz
Keyword(s):  
Diesel Engines ◽  
High Speed ◽  
State Of The Art ◽  
Abrasive Particles ◽  
Highly Efficient ◽  
Medium Speed ◽  
High Speed Diesel ◽  
Oil Flow ◽  
Flow Filtration ◽  
Filtration Surface

Traditional designs, using cartridge filters for full-flow filtration, protect medium speed and high speed diesel engines from wear and keep the concentration of abrasive particles in the oil system down by collecting them out of the circulating oil flow. After several hundred running hours the filtration surface is saturated, the cartridges get exchanged and disposed. State of the art automatic filters protect the engines against wear with the same efficiency as the cartridge filters but the backflushing mechanism keeps the filtration surface clean and the lubrication circuit remains maintenance free. The lifetime of filter elements lasts during time before overhaul (TBO) of the engine itself and is at least 24,000 hrs. The job to discharge the particles out of the system is done by highly efficient centrifugal oil cleaners in by-pass operation which separate not only the particles retained by the automatic filter but also very fine solids like soot. Figure 1 shows an automatic filter in cooperation with two centrifugal oil cleaners build into the silhouette of the engine.

Optimization on Resistance Performance of High Speed Unmanned Surface Vehicle in Middle-Low Speed

2011 ◽  
Vol 311-313 ◽  
pp. 2389-2392
Author(s):  
Wei Jia Ma ◽  
Hua Wei Sun ◽  
Yong Jie Pang
Keyword(s):  
High Speed ◽  
Optimization Method ◽  
Resistance Coefficient ◽  
Total Resistance ◽  
Hull Form ◽  
Unmanned Surface Vehicle ◽  
Low Speed ◽  
Non Linear Programming ◽  
Hull Forms ◽  
Resistance Performance

Unmanned surface vehicle has been the concern of the researchers at home and abroad as a new kind of unmanned platform ,especially for the middle-low speed resistance performance .An optimization method is proposed in this paper to find a hull form with perfect resistance performance in middle-low speed .This paper combines wave resistance and non-linear programming , Moreover, some hull forms are optimized to meet the combination of optimization punishing function with practical requirements and objective function to obtain Optimization form. The paper compared wave-making resistance coefficient and Total resistance (Newton) of Unit displacement (ton) between patent form and Optimization form to Show the feasibility of this method .The optimization results can provide reference for the subsequent hull form.

High speed and highly efficient Si optical modulator with strained SiGe layer

2015 ◽  
Author(s):  
Junichi Fujikata ◽  
Masataka Noguchi ◽  
Younghyun Kim ◽  
Shigeki Takahashi ◽  
Takahiro Nakamura ◽  
...  
Keyword(s):  
High Speed ◽  
Sige Layer ◽  
Optical Modulator ◽  
Highly Efficient ◽  
Strained Sige

Development and Assessment of a Total Resistance Optimized Bow for the AE 36

1994 ◽  
Vol 31 (02) ◽  
pp. 149-160
Author(s):  
Donald C. Wyatt ◽  
Peter A. Chang
Keyword(s):  
Experimental Data ◽  
Optimization Procedure ◽  
Wave Resistance ◽  
Scale Model ◽  
Optimization Approach ◽  
Nonlinear Constraints ◽  
Total Resistance ◽  
Hull Form ◽  
Final Design ◽  
Resistance Data

A numerically optimized bow design is developed to reduce the total resistance of a 23 000 ton ammunition ship (AE 36) at a speed of 22 knots. An optimization approach using slender-ship theory for the prediction of wave resistance is developed and applied. The new optimization procedure is an improvement over previous optimization methodologies in that it allows the use of nonlinear constraints which assure that the final design remains within practical limits from construction and operational perspectives. Analytic predictions indicate that the AE 36 optimized with this procedure will achieve a 40% reduction in wave resistance and a 33% reduction in total resistance at 22 knots relative to a Kracht elliptical bulb bow design. The optimization success is assessed by the analysis of 25th scale model resistance data collected at the David Taylor Research Center deepwater towing basin. The experimental data indicate that the optimized hull form yields a 51% reduction in wave resistance and a 12% reduction in total resistance for the vessel at 22 knots relative to the Kracht bulb bow design. Similarly encouraging results are also observed when comparisons are made with data collected on two other conventionally designed AE 36 designs.

Some Guidance for Hull Form Selection for SWATH Ships

1988 ◽  
Vol 25 (04) ◽  
pp. 239-252
Author(s):  
G. Robed Lamb
Keyword(s):  
High Speed ◽  
Early Stage ◽  
The United States ◽  
Practical Application ◽  
Hull Form ◽  
Stage Design ◽  
Seakeeping Performance ◽  
The World ◽  
Selection For ◽  
Early Stage Design

Even though in 1987 there were only a dozen SWATH (smali-waterplane-area twin-hull) craft and ships afloat around the world, word of their markedly superior seakeeping performance is spreading rapidly. The number of SWATH vessels is likely to double within five years. As in many other areas of technology, the United States and Japan are the acknowledged leaders in the development and practical application of the SWATH concept. This paper reviews the characteristics of existing SWATH craft and ships from the standpoint of the stated seakeeping objective. Hull form differences between four SWATH craft and ships, including the Navy's SSP Kairnalino, are analyzed and interpreted. Important considerations for the early-stage design of a SWATH ship are discussed. Differences in the range of feasible hull form geometries for coastal areas and unrestricted ocean operations, and for low-speed versus moderately high-speed applications, are pointed out.

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