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Resistance And Propulsion Of Ships Harvald Pdf

resistance and propulsion of ships harvald pdf

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Resistance and propulsion of ships

To browse Academia. Skip to main content. By using our site, you agree to our collection of information through the use of cookies. To learn more, view our Privacy Policy. Log In Sign Up. Download Free PDF. Miguel Santos. Stephen Turnock. Bill Erick Castillo. Download PDF. A short summary of this paper.

Stephen R. Professor Turnock lectures on many subjects, including ship resistance and propulsion, powercraft performance, marine renewable energy and applications of CFD. His research encompasses both experimental and theoretical work on energy efficiency of shipping, performance sport, underwater systems and renewable energy devices, together with the application of CFD for the design of propulsion systems and control surfaces.

Dominic A. Hudson lectures on ship resistance and propulsion, powercraft performance and design, recreational and high-speed craft and ship design. His research interests are in all areas of ship hydrodynamics, including experimental and theoretical work on ship resistance components, seakeeping and manoeuvring, together with ship design for minimum energy consumption.

PrefaceNew ship types and applications continue to be developed in response to economic, societal and technical factors, including changes in operational speeds and fluctuations in fuel costs.

These changes in ship design all depend on reliable estimates of ship propulsive power. There is a growing need to minimise power, fuel consumption and operating costs driven by environmental concerns and from an economic perspective.

The estimation of ship propulsive power is fundamental to the process of designing and operating a ship. Knowledge of the propulsive power enables the size and mass of the propulsion engines to be established and estimates made of the fuel consumption and likely operating costs.

The methods whereby ship resistance and propulsion are evaluated will never be an exact science, but require a combination of analysis, experiments, computations and empiricism. This book provides an up-todate detailed appraisal of the data sources, methods and techniques for establishing propulsive power.

Notwithstanding the quantity of commercial software available for estimating ship resistance and designing propellers, it is our contention that rigorous and robust engineering design requires that engineers have the ability to carry out these calculations from first principles.

This provides a transparent view of the calculation process and a deeper understanding as to how the final answer is obtained. An objective of this book is to include enough published standard series data for hull resistance and propeller performance to enable practitioners to make ship power predictions based on material and data contained within the book. A large number of fully worked examples are included to illustrate applications of the data and powering methodologies; these include cargo and container ships, tankers and bulk carriers, ferries, warships, patrol craft, work boats, planing craft and yachts.

The book is aimed at a broad readership, including practising professional naval architects and marine engineers and undergraduate and postgraduate degree students. It should also be of use to other science and engineering students and professionals with interests in the marine field.

The book is arranged in 17 chapters. The first 10 chapters broadly cover resistance, with Chapter 10 providing both sources of resistance data and useable xv xvi Preface data.

Chapters 11 to 16 cover propellers and propulsion, with Chapter 16 providing both sources of propeller data and useable data. Chapter 17 includes a number of worked example applications. For the reader requiring more information on basic fluid mechanics, Appendix A1 provides a background to the physics of fluid flow. Appendix A2 derives a wave resistance formula and Appendices A3 and A4 contain tabulated resistance and propeller data.

References are provided at the end of each chapter to facilitate readers' access to the original sources of data and information and further depth of study when necessary. These provide an invaluable source of reviews and developments of ship resistance and propulsion. The University of Southampton Ship Science Reports, referenced in the book, can be obtained free from www.

The authors acknowledge the help and support of their colleagues at the University of Southampton. Thanks must also be conveyed to national and international colleagues for their continued support over the years.

Particular acknowledgement should also be made to the many undergraduate and postgraduate students who, over many years, have contributed to a better understanding of the subject through research and project and assignment work.

Many of the basic sections of the book are based on notes of lectures on ship resistance and propulsion delivered at the University of Southampton. In this context, particular thanks are due to Dr. John Wellicome, who assembled and delivered many of the original versions of the notes from the foundation of the Ship Science degree programme in Southampton in Finally, the authors wish especially to thank their respective families for their practical help and support.

A knowledge of the propulsive power enables the size and mass of the propulsion engines to be established and estimates made of the fuel consumption and operating costs. The estimation of power entails the use of experimental techniques, numerical methods and theoretical analysis for the various aspects of the powering problem. The requirement for this stems from the need to determine the correct match between the installed power and the ship hull form during the design process.

An understanding of ship resistance and propulsion derives from the fundamental behaviour of fluid flow. The complexity inherent in ship hydrodynamic design arises from the challenges of scaling from practical model sizes and the unsteady flow interactions between the viscous ship boundary layer, the generated free-surface wave system and a propulsor operating in a spatially varying inflow. HistoryUp to the early s, little was really understood about ship resistance and many of the ideas on powering at that time were erroneous.

Propeller design was very much a question of trial and error. The power installed in ships was often wrong and it was clear that there was a need for a method of estimating the power to be installed in order to attain a certain speed.

In , W. Froude initiated an investigation into ship resistance with the use of models. He noted that the wave configurations around geometrically similar forms were similar if compared at corresponding speeds, that is, speeds proportional to the square root of the model length. He propounded that the total resistance could be divided into skin friction resistance and residuary, mainly wavemaking, resistance.

He derived estimates of frictional resistance from a series of measurements on planks of different lengths and with different surface finishes [1. Specific residuary resistance, or resistance per ton displacement, would remain constant at corresponding speeds between model and ship.

His proposal was initially not well received, but gained favour after full-scale tests had been carried out. HMS Greyhound ft was towed by a larger vessel and the results showed a substantial level of agreement with the model predictions Powering: Overall ConceptThe overall concept of the powering system may be seen as converting the energy of the fuel into useful thrust T to match the ship resistance R at the required speed V , Figure 1.

It is seen that the overall efficiency of the propulsion system will depend on:Fuel type, properties and quality. The efficiency of the engine in converting the fuel energy into useful transmittable power.

The efficiency of the propulsor in converting the power usually rotational into useful thrust T. The following chapters concentrate on the performance of the hull and propulsor, considering, for a given situation, how resistance R and thrust T may be estimated and then how resistance may be minimised and thrust maximised.

Accounts of the properties and performance of engines are summarised separately. Thisis the traditional breakdown and allows the assessment of the individual components to be made and potential improvements to be investigated.

Improvements in EfficiencyThe factors that drive research and investigation into improving the overall efficiency of the propulsion of ships are both economic and environmental. The main economic drivers amount to the construction costs, disposal costs, ship speed and, in particular, fuel costs.

These need to be combined in such a way that the shipowner makes an adequate rate of return on the investment. The main environmental drivers amount to emissions, pollution, noise, antifoulings and wave wash. Whilst NOx and SOx mainly affect coastal regions, carbon dioxide CO 2 emissions have a The following chapters describe the basic components of ship powering and how they can be estimated in a practical manner in the early stages of a ship design.

The early chapters describe fundamental principles and the estimation of the basic components of resistance, together with influences such as shallow water, fouling and rough weather. The efficiency of various propulsors is described including the propeller, ducted propeller, supercavitating propeller, surface piercing and podded propellers and waterjets.

Attention is paid to their design and off design cases and how improvements in efficiency may be made. Databases of hull resistance and propeller performance are included in Chapters 10 and Worked examples of the overall power estimate using both the resistance and propulsion data are described in Chapter References are provided at the end of each chapter.

Further more detailed accounts of particular subject areas may be found in the publications referenced and in the more specialised texts such as [1.

Surface ship total resistance prediction based on a nonlinear free surface potential flow solver and a Reynolds-averaged Navier-2 Propulsive Power Components of Propulsive PowerDuring the course of designing a ship it is necessary to estimate the power required to propel the ship at a particular speed.

This allows estimates to be made of: a Machinery masses, which are a function of the installed power, and b The expected fuel consumption and tank capacities. The power estimate for a new design is obtained by comparison with an existing similar vessel or from model tests. In either case it is necessary to derive a power estimate for one size of craft from the power requirement of a different size of craft.

That is, it is necessary to be able to scale powering estimates. The different components of the powering problem scale in different ways and it is therefore necessary to estimate each component separately and apply the correct scaling laws to each.

One fundamental division in conventional powering methods is to distinguish between the effective power required to drive the ship and the power delivered to the propulsion unit s. The main components considered when establishing the ship power comprise the ship resistance to motion, the propeller open water efficiency and the hullpropeller interaction efficiency, and these are summarised in Figure 2.

Ship power predictions are made either by 1 Model experiments and extrapolation, or 2 Use of standard series data hull resistance series and propeller series , or 3 Theoretical e. Propulsion SystemsWhen making power estimates it is necessary to have an understanding of the performance characteristics of the chosen propulsion system, as these determine the operation and overall efficiency of the propulsion unit.

Propeller chatacteristics in open water Self-propulsion Hull-propeller interaction Propeller 'boat' or cavitation tunnel Each type of propulsion engine and propulsor has its own advantages and disadvantages, and applications and limitations, including such fundamental attributes as size, cost and efficiency. All of the these propulsion options are in current use and the choice of a particular propulsion engine and propulsor will depend on the ship type and its design and operational requirements.

Propulsors and propulsion machinery are described in Chapters 11 and The overall assessment of the marine propulsion system for a particular vessel will therefore require: 1 A knowledge of the required thrust T at a speed V , and its conversion into required power P , 2 A knowledge and assessment of the physical properties and efficiencies of the available propulsion engines, 3 The assessment of the various propulsors and engine-propulsor layouts.

The total installed power will exceed the delivered power by the amount of power lost in the transmission system shafting and gearing losses , and by a design power margin to allow for roughness, fouling and weather, i. Main hull naked resistance. Resistance of appendages such as shafting, shaft brackets, rudders, fin stabilisers and bilge keels.

Air resistance of the hull above water. The QPC depends primarily upon the efficiency of the propulsion device, but also depends on the interaction of the propulsion device and the hull.

Harvald, Resistance and Propulsion of Ships

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Harvald, Resistance and Propulsion of Ships

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Harvald, Resistance and Propulsion of Ships

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Harvald, Resistance And Propulsion Of Ships

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SHIP RESISTANCE AND PROPULSION

Еще только начинало светать, но движение уже было довольно оживленным: молодые жители Севильи возвращались после ночных пляжных развлечений. Резко просигналив, пронесся мимо мини-автобус, до отказа забитый подростками. Мотоцикл Беккера показался рядом с ним детской игрушкой, выехавшей на автостраду.

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Harvald, Resistance and Propulsion of Ships

Грубость Джаббы была недопустима, но директор понимал, что сейчас не время и не место углубляться в вопросы служебной этики.

2 Comments

  1. Paiperdelef

    19.04.2021 at 03:50
    Reply

    Harvald gives additional correction for these parameters. The residual resistance coefficient curves must be corrected for. • Position of LCB (∆.).

  2. Merlin S.

    21.04.2021 at 06:20
    Reply

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