Experimental Verifications of a Theoretical Procedure for Propeller-Induced Hull Pressure Calculations

1984 ◽  
Vol 21 (02) ◽  
pp. 119-133
Author(s):  
A. Colombo ◽  
B. Chilo'
Keyword(s):  
Computer Program ◽  
Full Scale ◽  
Pressure Amplitude ◽  
Towing Tank ◽  
Ship Model ◽  
Single Screw ◽  
Propeller Design ◽  
Experimental Values ◽  
New Generation ◽  
Theoretical Procedure

This paper describes the methodologies adopted by the Italian Ship Research Center to predict propeller-induced pressures. An outline of the developed computer program is given, and calculated pressure amplitude results for two ships are compared with the experimental values obtained from full-scale measurements. In particular, calculated pressure results, produced by three different propeller design solutions at several points on the stern of a new-generation single-screw roll-on/roll-off containership, are discussed and compared with the same quantities measured both on a ship model in the Depressurized Towing Tank of the Netherlands Ship Model Basin and on the full-scale ship fitted with the selected propeller.

Ship-Model Correlation of Powering Performance on USS Oliver Hazard Perry, FFG-7 Class

1983 ◽  
Vol 20 (01) ◽  
pp. 35-52
Author(s):  
Everett L. Woo ◽  
Gabor Karafiath ◽  
Gary Borda
Keyword(s):  
Performance Prediction ◽  
Prediction Method ◽  
Model Tests ◽  
Trial Data ◽  
Full Scale ◽  
Ship Model ◽  
Single Screw ◽  
Post Trial ◽  
Model Correlation

Standardization trials were conducted on USS Oliver Hazard Perry (FFG-7) in May 1978. From the results of the trial data and the post-trial model correlation experiments which simulated the trial conditions, the powering correlation allowance of 0.00045 was obtained for the FFG-7. It should be noted that the pretrial model tests used the design correlation allowance of 0.0005 to predict full-scale powering performance. In addition, the powering performance was predicted using the "1978 ITTC Performance Prediction Method for Single Screw Ships."

scholarly journals Application of Measurement Sensors and Navigation Devices in Experimental Research of the Computer System for the Control of an Unmanned Ship Model

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1312 ◽  
Author(s):  
Tadeusz Szelangiewicz ◽  
Katarzyna Żelazny ◽  
Andrzej Antosik ◽  
Maciej Szelangiewicz
Keyword(s):  
Computer Program ◽  
Computer System ◽  
Autonomous Control ◽  
Maritime Transport ◽  
Control Software ◽  
Ship Model ◽  
Steering Characteristics ◽  
Unmanned Ship ◽  
Transport Vessel ◽  
Navigation Equipment

Unmanned autonomous transport vessels (MASS) are the future of maritime transport. The most important task in the design and construction of unmanned ships is to develop algorithms and a computer program for autonomous control. In order for such a computer program to properly control the ship (realizing various functions), the ship must be equipped with a computer system as well as measurement sensors and navigation devices, from which the recorded parameters are processed and used for autonomous control of the ship. Within the framework of conducted research on autonomous ships, an experimental model of an unmanned ship was built. This model was equipped with a propulsion system not commonly used on transport vessels (two azimuth stern thrusters and two bow tunnel thrusters), but providing excellent propulsion and steering characteristics. A complete computer system with the necessary measuring sensors and navigation devices has also been installed in the model of the ship, which enables it to perform all functions during autonomous control. The objective of the current research was to design and build a prototype computer system with the necessary measurement sensors and navigation devices with which to autonomously control the unmanned ship model. The designed computer system is expected to be optimal for planned tasks during control software tests. Tests carried out on open waters confirmed the correctness of the operation of the computer system and the entire measurement and navigation equipment of the built model of the unmanned transport vessel.

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.

THE INFLUENCE OF CENTRE BOW LENGTH ON SLAMMING LOADS AND MOTIONS OF LARGE WAVE-PIERCING CATAMARANS

2021 ◽  
Vol 160 (A1) ◽  
Author(s):  
J R Shahraki ◽  
G A Thomas ◽  
M R Davis
Keyword(s):  
Wave Height ◽  
Full Scale ◽  
Bending Moments ◽  
Regular Waves ◽  
Large Wave ◽  
Towing Tank ◽  
Segmented Model ◽  
Model Experiments ◽  
Slamming Load ◽  
Wave Induced

The effect of various centre bow lengths on the motions and wave-induced slamming loads on wave-piercing catamarans is investigated. A 2.5 m hydroelastic segmented model was tested with three different centre bow lengths and towed in regular waves in a towing tank. Measurements were made of the model motions, slam loads and vertical bending moments in the model demi-hulls. The model experiments were carried out for a test condition equivalent to a wave height of 2.68 m and a speed of 20 knots at full scale. Bow accelerations and vertical bending moments due to slamming showed significant changes with the change in centre bow, the longest centre bow having the highest wave-induced loads and accelerations. The increased volume of displaced water which is constrained beneath the bow archways is identified as the reason for this increase in the slamming load. In contrast it was found that the length of centre bow has a relatively small effect on the heave and pitch motions in slamming conditions.

scholarly journals A comparative review of the resistance of a 37,000 dwt Chemical Tanker based on experimental tests and calculations

2020 ◽  
Vol 1 ◽  
pp. 59-66
Author(s):  
Liviu Crudu ◽  
Radu Bosoancă ◽  
Dan Obreja
Keyword(s):  
Energy Efficiency ◽  
Experimental Tests ◽  
Full Scale ◽  
The Other ◽  
Towing Tank ◽  
Ship Resistance ◽  
Comparative Review ◽  
Cfd Applications ◽  
Energy Efficiency Design Index ◽  
Comparison Of The Results

The evaluation of ship resistance is of paramount importance having a decisive impact on the economic performances and efficiency depending on mission. If new IMO requirements through the Energy Efficiency Design Index (EEDI) are taken into account the necessity to have more and more accurate tools capable to consider the influences of different parameters became mandatory. The availability of towing tank facilities and the full scale trials are the practical means in order to be able to confirm the accuracy of theoretical formulations and to define the limits of CFD applications. Based on the results of the towing tank tests, a direct comparison with the results provided by classical methods and CFD computations can be systematically can be performed. On the other hand, the influences of the modifications operated on the fore part of the ship aretheoretically evaluated and compared with the towing tank results. Consequently, the paper is focused on the comparison of the results evaluated using different tools which have been carried out for a Chemical Tanker built by Constanta Shipyard Romania.

scholarly journals Full-scale self-propulsion simulation with a discretized propeller

2021 ◽  
Vol 4 (398) ◽  
pp. 15-23
Author(s):  
Zhang Qingshan ◽  
◽  
Chen Weimin ◽  
Du Yunlong ◽  
Dong Guoxiang ◽  
...  
Keyword(s):  
Boundary Layer Thickness ◽  
Polynomial Interpolation ◽  
Flow Characteristics ◽  
Uncertainty Assessment ◽  
Full Scale ◽  
The Self ◽  
High Fidelity ◽  
Cfd Simulations ◽  
Towing Tank ◽  
Grid Application

A comparison between towing tank testing and full-scale CFD simulations is presented at three different target speeds. For the current self-propulsion simulation, the self-propulsion point was obtained using polynomial interpolation. The studies of boundary layer thickness, a basic grid uncertainty assessment and verification were performed to give some confidence of grid application to current self-propulsion simulation. All simulations are performed using a commercial CFD software STAR-CCM+. It is concluded that with high-fidelity numerical methods, it’s possible to treat hull roughness and directly calculate full-scale flow characteristics, including the effects of the free surface, none-linearity, turbulence and the interaction between propeller, hull and the flow field.

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.

An Introduction to Ethnotechnology for Naval Architects: Sea Kayak Design of Yesterday and Tomorrow

1994 ◽  
Vol 31 (04) ◽  
pp. 305-314
Author(s):  
Peter Noble ◽  
Michael Wadden ◽  
Timothy Bourke ◽  
David Williams ◽  
Knut Nordbo
Keyword(s):  
Full Scale ◽  
Design Development ◽  
Towing Tank

The skin-covered kayaks and baidarkas of the Inuit and Aleut peoples are elegant examples of naval architectural technology developed over centuries of experimental refinement. This paper describes the ethnotechnology which lies behind the design of modern sea kayaks and discusses the development of the DeCourcy Duet, a two-hole kayak, which utilizes numerical lines fairing, extensive computer stability calculations and full-scale towing tank testing as part of its design development.

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