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.

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.

Experimental Investigation on Resistance Reduction by Means of Air-Bubbling Technique

2018 ◽  
Author(s):  
Enrico Ravina ◽  
Sofia Guidomei
Keyword(s):  
Flow Rate ◽  
Low Cost ◽  
Frictional Resistance ◽  
Flat Plates ◽  
Research Activity ◽  
Frictional Drag ◽  
Towing Tank ◽  
Resistance Reduction ◽  
The University ◽  
Different Levels

The paper refers on a research activity, focused at DREAMS Lab of the University of Genoa (Italy) and still under development, oriented to experimental application of air-bubbling techniques on flat plates and hull models. In this study the reduction in the frictional resistance by air bubbling generated by customized pneumatic circuits is tested, both on the lower surfaces of flat plates characterized of different geometries of holes and on a hull model tested in towing tank. The effective shape of air bubbles is observed, and changes in the local frictional drag are measured, using flexible and low cost thin sensors at different levels of flow rate and pressure of injected air. In towing tank tests the experiments compare hull without and with holes on the bottom, modifying the characteristics of speed, pressure, flow rate and areas interested to the air injection. Systematic tests campaign has been developed, using also actuation pneumatic workbenches expressly designed for the experiments.

The Effect of Air Lubrication on a Flat Plate at Varying Angles of Trim With Regard to Drag Reduction

2013 ◽  
Author(s):  
Sean P. Murphy ◽  
Colin T. Spillane
Keyword(s):  
Drag Reduction ◽  
Flat Plate ◽  
Fuel Consumption ◽  
Technological Development ◽  
Frictional Resistance ◽  
Flow Volume ◽  
Resistance Reduction ◽  
Flow Speeds ◽  
Air Lubrication ◽  
Air Layer Drag Reduction

One of the driving factors of technological development in ship design is the reduction of fuel consumption. One way to reduce fuel consumption is to reduce the total resistance experienced by a vessel. The methods of resistance reduction covered in this document are Air-layer-drag-reduction (ALDR) and Bubble Drag Reduction (BDR). This research, conducted in Webb Institute’s circulating flow channel, investigates the applications of ALDR and BDR to a flat plate. These tests measured frictional resistance at varying air flow volume and angles of trim over a range of flow speeds. Results from these tests offer compelling evidence that ALDR is an effective method of reducing frictional resistance.

Slamming Events of a Planing Hull and Wedge Water Entry Experiment: Comparisons and Insights on Fluid-Structure Interaction

2021 ◽  
Author(s):  
Lauren Honey ◽  
Carolyn Q. Judge ◽  
Christine M. Gilbert
Keyword(s):  
Dimensional Analysis ◽  
Virginia Tech ◽  
Water Entry ◽  
Naval Academy ◽  
Towing Tank ◽  
Structure Interaction ◽  
Towing Tank Test ◽  
Tank Test ◽  
Free Falling ◽  
The U.S

Both towing tank experiments and wedge drop experiments are used to experimentally study slamming events on planning craft. The work presented in this paper shows a unique comparison between these two experiments. The first experiment was a towing tank test of a rigid hull in waves conducted at the U.S. Naval Academy. The second experiment was a series of free-falling water entry tests on a wedge conducted at Virginia Tech. In this paper, comparisons are drawn between the two experiments by using non-dimensional analysis and isolating similar slamming events. The non-dimensional impact velocities are chosen to be identical.

scholarly journals Nomoto Indices for Constant-Depth Zigzag Manoeuvres of an Autonomous Underwater Vehicle

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Farhood Azarsina ◽  
Christopher D. Williams
Keyword(s):  
Autonomous Underwater Vehicle ◽  
Underwater Vehicle ◽  
Test Results ◽  
Constant Depth ◽  
Simulation Code ◽  
Towing Tank ◽  
The Past ◽  
Towing Tank Test ◽  
Tank Test ◽  
Dimensional Simulation

A two-dimensional simulation code is used to study the characteristics of constant-depth zigzag manoeuvres of the axisymmetric autonomous underwater vehicle (AUV) MUN Explorer. Sea trials data for several manoeuvres with the AUV have been reported during the past four years; however, to obtain a more complete understanding of the vehicle's hydrodynamics, additional towing tank tests and computer simulation were performed. The present work, based on the towing tank test results and sea-trials data, utilizes computer simulations to predict the performance of the MUN Explorer AUV during horizontal zigzag manoeuvres. Next, the Nomoto indices for this AUV during constant-depth zigzag manoeuvres are estimated using the simulation results, and, then, Nomoto's first-order model for the rate of turn of the vehicle during horizontal zigzag manoeuvres in response to a square-wave input for the rudder deflection angle is analytically solved. The paper investigates the validity of the simplified yaw equation to predict a zigzag manoeuvre. Results of this research are a first step to understand the details of zigzag manoeuvres of an AUV such as duration of the first execute, yaw-checking ability, and duration of the overshoot.

A New Velocity Prediction Method for Post-Processing of Towing Tank Test Results

2005 ◽  
Author(s):  
Kai Graf ◽  
Christoph Bohm
Keyword(s):  
Prediction Method ◽  
Hydrodynamic Coefficients ◽  
Test Results ◽  
Towing Tank ◽  
Prediction Program ◽  
Rule Changes ◽  
Velocity Prediction ◽  
Towing Tank Test ◽  
Tank Test ◽  
The Impact

A velocity prediction program (VPP) has been developed at the UAS Kiel, which implements a new method to model the hydrodynamic forces acting on the hull and appendages of a sailing yacht. Based on linear wing theory the model allows the derivation of a set of hydrodynamic coefficients for the VPP from a limited set of towing tank test runs. This approach makes the new VPP, called AVPP, in particular suitable to serve as a towing tank post-processor. The paper describes AVPP, the hydrodynamic model and the math behind the derivation of hydrodynamic coefficients from tank test results. Two examples are shown: a study of the impact of the ACC V4/V5 rule changes and a comparison of a canting keel and a conventional keel yacht.

scholarly journals Influence of hull entrance angle “Perintis 750 DWT”, toward ship resistance: the case study for design development “Perintis 750 DWT.”

2018 ◽  
Vol 159 ◽  
pp. 01057
Author(s):  
Eko Sasmito Hadi ◽  
Parlindungan Manik ◽  
Muhammad Iqbal
Keyword(s):  
Fluid Dynamic ◽  
Ship Design ◽  
Design Development ◽  
Entrance Angle ◽  
Towing Tank ◽  
Sea Transportation ◽  
Towing Tank Test ◽  
Tank Test ◽  
Energy Efficiency Design Index

Geographically Indonesia which most of its territory consists of the sea, causing the necessity of strengthening maritime facilities and infrastructure to conduct activities of distribution of goods and sea transportation facilities, especially ships as a vehicle of sea transportation to maintain inter-island connectivity. Indonesian government builds national connectivity (sea tolls) by the development of pioneer ship design “Kapal Perintis.”. In this study, the vessel Perintis 750 DWT is still lacking in the EEDI (Energy Efficiency Design Index) aspect as required by IMO, so it is necessary to modify the hull part of the vessel to reduce the resistance. The modified hull is carried out by varying the angle of entrance bow of the ship ± 12° in step of 3°. Modifications were made using Delftship software, Computational Fluid Dynamic, called TDyn and verified by towing tank test at Indonesian Hydrodynamics Laboratory (IHL) Surabaya. Every change of the angle of entrance bow in 3 degrees, the ship's resistance will change more and less 3.5%. The smaller angle of entrance bow of the vessel the smaller ship's resistance.

scholarly journals Boundary Layer Mixture Model for a Microbubble Drag Reduction Technique

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Jing-Fa Tsai ◽  
Chi-Chuan Chen
Keyword(s):  
Boundary Layer ◽  
Drag Reduction ◽  
Flat Plate ◽  
Mixture Model ◽  
Frictional Resistance ◽  
Reduction Technique ◽  
Measuring System ◽  
Water Tunnel ◽  
Towing Tank ◽  
Reduction Effect

The boundary mixture model is derived to predict the performance of the microbubble drag reduction technique for a flat plate. The flat plate with a porous material microbubble injecting system and resistance-measuring system are set up to measure the frictional resistance of the flat plate without and with injected microbubbles. The tests are conducted in a water tunnel and a towing tank. The test results show that the boundary mixture model predicts the drag reduction well for the flat plate when testing with injected microbubbles in the water tunnel. However, the boundary mixture model overestimates the drag reduction effect for the flat plate tested in the towing tank. The possible mechanism for the overestimation of drag reduction effect in the towing tank may be due to the different behaviors of microbubbles in the velocity gradient of boundary layer.

scholarly journals Comparison of Selected Parametric Methods for Prediction of Inland Waterways Ship Hull Resistance in Towing Tank Test

2018 ◽  
Vol 25 (s1) ◽  
pp. 63-67
Author(s):  
Artur Karczewski ◽  
Janusz Kozak
Keyword(s):  
Design Stage ◽  
Preliminary Design ◽  
Parametric Methods ◽  
Test Results ◽  
Approximate Methods ◽  
Inland Waterways ◽  
Towing Tank ◽  
Preliminary Design Stage ◽  
Towing Tank Test ◽  
Tank Test

Abstract In the paper selected approximate methods for calculation of inland waterways ship resistance and their verification by towing tests, compared on the example of a small urban ferry, are presented. The test results are made for both the bare hull and the hull with appendages (skeg, azimuthal propeller). Significant differences between results of the theoretical methods and experimental ones, especially in the case of the model with skegs and propulsion, are pointed out. The purposefulness of using several parametric methods and the use of average results at the preliminary design stage were also discussed.

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