WATERJET PROPULSION SYSEM FOR HIGH SPEED CRAFTS

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1 ARAB ACADEMY FOR SCIENCE, TECHNOLOGY AND MARITIME TRANSPORT COLLEGE OF ENGINEERING AND TECHNOLOGY WATERJET PROPULSION SYSEM FOR HIGH SPEED CRAFTS Thesis Submitted to The Marine Engineering Department In Partial Fulfillment of the Requirements for the Degree of Masters of Science In Marine Engineering Submitted by Abdel Monem Mohamed Omar Abul-Fadl BSc. In Marine Engineering College Of Engineering And Technology Arab Academy For Science, Technology And Maritime Transport Alexandria, Egypt. AUGUST 2006

2 ARAB ACADEMY FOR SCIENCE, TECHNOLOGY AND MARITIME TRANSPORT COLLEGE OF ENGINEERING AND TECHNOLOGY WATERJET PROPULSION SYSEM FOR HIGH SPEED CRAFTS Thesis Submitted to The Marine Engineering Department In Partial Fulfillment of the Requirements for the Degree of Masters of Science In Marine Engineering Submitted by Abdel Monem Mohamed Omar Abul-Fadl BSc. In Marine Engineering College Of Engineering And Technology Arab Academy For Science, Technology And Maritime Transport Alexandria, Egypt. Supervised by Prof. Dr. Ahmad Abd-AlAziz Albadan Professor of Naval Architecture and Marine Engineering Marine Engineering Department Faculty of Engineering-Alexandria University Ass. Prof. Dr. Mohamed Abbas Kotb Professor of Naval Architecture and Marine Engineering Marine Engineering Department Faculty of Engineering-Alexandria University AUGUST 2006

3 DECLARATION We certify that we have read the present work and that in our opinion it is fully adequate in scope and quality as a dissertation towards the fulfillment of the Master degree requirements in Mechanical and Marine engineering from the Arab academy for Science and Technology and Maritime Transport. External Examiners Prof. Dr. Mohamed A. A. Mosaad Vice Dean of the Engineering Department of Qanat El Suez University Prof. Dr. Ahmad Mohammad Rashwan Professor Doctor in the Marine Engineering Department of Alexandria University Signature Signature Supervisors Prof. Dr. Ahmad Abd- AlAziz El-Badan Professor Doctor in the Marine Engineering Department of Alexandria University Prof. Dr. Mohamed Abbas Kotb Professor Doctor in the Marine Engineering Department of Alexandria University Signature Signature

4 Dedication To My Parents and Grand Parents ii

5 Acknowledgment I would like to express my deep and sincere thanks to Prof. Dr/ Ahmed El Badan for proposing the subject of this thesis. His never ending support and helpful suggestions have been of great value in the accomplishment of this work. I also owe a special debt of cordial gratitude to Prof. Dr/ Mohamed Abbas Kotb who dedicated much of his time and effort for this work to be achieved. His instructive supervision, constructive criticism, enlightening thoughts and laborious efforts have made this thesis a reality. I would like to express my deep thanks to Dr. Mohammed El Ghamry for his efforts, constructive criticism and support to achieve this thesis. I also like to thank my professors and staff members at the Arab Academy for Science and Technology and Maritime Transport for their help, support and encouragement throughout my studies. And also my friends and colleagues especially at work for their help, encouragement and support Finally, I will always hold the deepest gratitude for my parents, grand parents and family for their never ending support, help and encouragement especially my wife for her help, dedication, constructive criticism and care. i

6 ABSTRACT The use of waterjet as a mean for propulsion is a non-conventional way to propel ships. There is an increasing demand for waterjet propulsion systems world wide for use in high-speed crafts and that requiring low draft, relatively low noise, high maneuverability and less power demand at high speeds. This research aims to study the principals of waterjet as a propulsion device. The use of waterjet propulsion devices on different hull types, mission and characteristics are presented. The study discusses the basic components of a waterjet propulsion device and composing materials. Basic equations regarding waterjet component calculations and performance characteristics are presented and discussed. The current work deals with the fact that waterjet propulsion devices are not designed and built by a single manufacturer. The pump, engine and transmissions are designed and matched together to give the optimum efficiency. The design and matching criteria are applied to a case, where a suitable waterjet propulsion system was selected for use on a fast response fire fighting boat. The selection process concentrated on the merits of using a single unit or a multi unit propulsion system and determining the power requirements of each case. The research ends with the conclusions drawn from the research and study. iii

7 LIST OF CONTENTS Acknowledgement... i Dedication...ii Abstract...iii List of symbols... iv List of content... ix List of figures...xii List of tables... xvi CHAPTER ONE INTRODUCTION Historical Background Literature Review Objective of This Study Framework of Thesis... 4 CHAPTER TWO WATER JET AS A MEANS FOR PROPULSION General Description Theory of Operation Classification of Waterjet Systems Waterjet Applications Hull Classification Waterjet Propulsion System Loads CHAPTER THREE DETAILED DESCRIPTION OF WATER JET PROPULSION SYSTEM COMPONENTS Inlets Cavitation Inlet Losses Pumps Water Jet Pumps Centrifugal Pumps Mixed Flow Pumps Axial Flow Pumps ix

8 Inducer Pumps Water Jet Pump Characteristics Nozzle Steering and Reversing Gear Reverse and Braking Prime Movers (Engines) Gear Boxes Other Components Shaft, Bearings, Thrust Block and Water Seal Pump Casing Steering and Reversing Mechanisms Materials CHAPTER FOUR BASIC EQUATIONS AND PERFORMANCE CHARACERISTICS theoretical basis Newton s Second Law Continuity Equation Energy Principle Gross Thrust Momentum Drag Inclusion of Inlet Losses Inclusion of Different Parameters Inlet Losses Effect of Nozzle Elevation Water Jet Hull Interaction Effects Pumps and Inlets Pump Performance Desirable Pump Characteristics for Water Jet Propulsion Flow Considerations Cavitation Considerations Performance Coefficients Speed-Power Coefficient Speed-Thrust Coefficient x

9 4.8.3 Power-RPM Coefficient CHAPTER FIVE CASE STUDY WATER JET SELECTION Selection Parameters Description Ship Design and Hydrostatics Model Maker Program Auto Hydro Program Resistance Calculations Savitsky Method Equations Calculating Procedure Water Jet Selection CHAPTER SIX CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE STUDIES Conclusions Recommendations for Future Studies REFRENCES.127 xi

10 LIST OF FIGURES Figure (2-1) Basic components of a water jet propulsion system... 6 Figure (2-2) Flow through a typical waterjet system Figure (2-3) Flow exiting a typical waterjet system... 8 Figure (2-4) A waterjet propulsion system containing two waterjet units with deflector buckets and a middle waterjet booster unit Figure (2-5) Fully retracted deflector buckets showing a steerable nozzle Figure (2-6) A waterjet system in the shop, with the reverse buckets fully retracted Figure (2-7) A waterjet system with fully extended deflector buckets indicating full reverse mode Figure (2-8) performance curve of a 432 millimeter single stage axial flow impeller input power and speed operating ranges Figure (2-9) Shape and physical size of the waterjet unit, using a 432 millimeter axial impeller Figure (2-10) 216 millimeter single axial flow impeller input power and speed operating ranges Figure (2-11) Performance curve for different pump sizes of the same series. (292, 322, 364, and 403) represent the impeller outer diameter in millimeters Figure (2-12a) A displacement chart, illustrating the relation between the maximum recommended displacement of the ship, the number of waterjet units and the size of the waterjet as a series number Figure (2-12b) Recommended waterjet characteristic curves Figure (2-13) Manufacturers recommendations for two different types of hulls Figure (2-14) Manufacturer recommendations for a larger waterjet unit Figure (2-15a) A typical waterjet Figure (2-15b) dimensions and weight of waterjets of the same series Figure (3-1) 3-D CAD drawing of a 115 type waterjet intake 23 Figure (3-2) Partial Section revealing an installed water jet system with a Flush Inlet 23 Figure (3-3) Cross Section of a Pod type Inlet Figure (3-4) Bottom view of a dry docked boat with an installed water jet system, revealing the intake with a mesh guard and two auxiliary boosters xii

11 Figure (3-5) A Schematic of an installed water jet system with a Pod Inlet. Dotted lines mark the flow of water to the pump Figure (3-6) A hydrofoil ferry at maximum speed completely air borne Figure (3-7) A cross section in a pod inlet shows the effect of different inlet velocity ratios on cavitation Figure (3-8) A curve representing model test results predicting the cavitation bucket for a 100 knot ship Figure (3-9) Section view of different types of impellers Figure (3-10) A section view showing a radial flow water jet pump Figure (3-11) Schematic of a centrifugal pump installed in a water jet system and flow of water through the system Figure (3-12) Typical characteristic curves of a centrifugal pump verses the system curves Figure (3-13) Upper Schematic of an installed mixed flow pump water jet. Bottom a section showing the internals of a mixed flow water jet Figure (3-14) Size comparison between Axial and radial flow pumps Figure (3-15) Inducer pump impeller, (A) front view, (B) Cross section Figure (3-16) Two views showing a horizontally mounted prime mover and a vertically mounted prime mover Figure (3-17) A front view of a Mixed flow impeller Figure (3-18) Relation between ship s speed, suction specific speed and thrust Figure (3-19) The relation between the pump delivered capacity, total head rise and power required in relation to pump efficiency Figure (3-20) The relation between flow orientation, specific speed, capacity and the expected efficiency Figure (3-21) A schematic of a water jet pump with a Pelton type nozzle Figure (3-22) An installed Pelton type nozzle during a shop test Figure (3-23) A water jet system with an installed axial flow pump and a well rounded tapered nozzle Figure (3-24) Velocity distribution of the discharge flow of a water jet nozzle Figure (3-25) (a) Steering sleeve deflecting thrust to the starboard side, (b) Reversing bucket in the three modes of operation Figure (3-26) A schematic showing the flow reduction concept xiii

12 Figure (3-27) Reversing \ Braking bucket fully deployed in an installed water jet system Figure (3-28) In-line arrangement of a diesel powered water jet system Figure (3-29) A water jet system powered by a marine gas turbine (upper) and installed on a navy hydrofoil (lower) Figure (3-30) shows a V-shape diesel engine installed on a water jet unit in a small size 12-foot pleasure boat Figure (3-31) A water jet unit with a vertically mounted engine Figure (3-32) Performance curve of a reduction gear, showing the relation between input power and engine speed (rpm) Figure (3-33) A step-up gear box with the top cover removed Figure (3-34) A typical gear box Figure (3-35) A six bladed impeller and a thrust block Figure (3-36) Hydraulic power pack and lubricating oil system Figure (3-37) Hydraulic connections at the after section of the water jet system Figure (4-1) Representing the forces acting on the ship when changing the direction of the nozzle Figure (4-2) A generic relation between side force and reduction in forward thrust (Gross Thrust = 20000N) Figure (4-3) A generic relation between gross thrust reduction percentage and steering degrees Figure (4-4) relation between jet efficiency, inlet losses and velocity ratio Figure (4-5) Effect of pump and jet elevation above ship bottom plating Figure (4-6) A schematic showing the lift force at ship high speed Figure (4-7) Schematic of a propeller powered ship, showing the propeller influence effect on the stern of the ship Figure (4-8) Waterjet inlet flow patterns Figure (4-9) Transom-mounted waterjet propulsion Figure (4-10) Lifting force due to pressure on the bottom plating and inlet for a KaMeWa waterjet installation Figure (4-11) Generic pump characteristics curve Figure (4-12) Approximate relative impeller shapes and efficiency variations with specific speed xiv

13 Figure (4-13) Generic non-dimensional pump characteristics Figure (5-1) An outboard profile and deck plans Figure (5-2) Command format used in the Model Maker program to draw the ship s lines Figure (5-3) Body Plan view Figure (5-4) Plan view Figure (5-5) Profile view Figure (5-6) Isometric view, looking aft Figure (5-7) Isometric view, looking forward Figure (5-8) List of commands to calculate ship s hydrostatics Figure (5-9) A schematic indicating the general forces acting on the boat Figure (5-10) nomograph for equilibrium conditions when ( ) Deadrise angle equals zero and all forces act through CG and for given values of Cv and p/b Figure (5-11) Curve representing the total drag (resistance) verses ship s speed Figure (5-12) Thrust/Resistance curve verses ship velocity Figure (5-13) A typical thrust/resistance curve Figure (5-14) Actual Thrust/resistance curve verses ships speed for two waterjets Figure (5-15) Curve representing the required effective power at various ship speeds122 Figure (5-16) Typical Power-RPM curves xv

14 LIST OF TABLES Table (2-1) Types and classification of boats and ships with installed waterjet propulsors Table (2-2) Waterjet applications and propulsion characteristics Table (3-1) Approximate correlation between flow orientation and values of specific speed Table (3-2) Different Component Materials Table (5-1) Fast response fire boat characteristics Table (5-2) Propulsion/ pumping requirements Table (5-3) List of weights Table (5-4) Given and calculated data Table (5-5) Inputs and results for LCG = 3.5 meters Table (5-6) Inputs and results for LCG = 4 meters Table (5-7) Inputs and results for LCG = meters Table (5-8) Inputs and results for LCG = 5.5 meters Table (5-9) Selection Results xvi

15 LIST OF SYMBOLS A pi A pt pump inlet area Projected area above waterline b BWL Beam Beam at water line C air Still air resistance coefficient C Di Inlet drag coefficient C fo Friction coefficient C l Lift force coefficient C Lb Flat plat lift force coefficient C Lβ Lift force coefficient for a finite dead rise C p C v d D i D i ehp " E EP E r F nb F s Pressure coefficient Speed Coefficient Impeller diameter Inlet lip drag Impeller diameter Effective horse power Useful energy supplied to pump Effective power Inlet energy Froude number based on beam Side force 2 g Gravity acceleration ( = 9.81m s ) H AT Atmospheric head H BEP pump head at best efficiency point h DD Inlet head loss due to the installation of a diffuser h Di Intake head loss H i Elevation of pump shaft above sea level iv

16 h j HP H p Jet elevation (height above bottom plating) Horse Power Pump head h pi Static head at pump inlet H v Vapor pressure ID IVR J K Kts k T KW LCB LCF Inner diameter (Inside Diameter) Inlet velocity ratio Flow coefficient Coefficient Knots Pressure coefficient Kilowatt Longitudinal center of buoyancy Longitudinal center of floatation L cg Longitudinal center of gravity LCG L m LWL m Longitudinal center of gravity Wetted length Length at water line water mass flow rate m i Mass flow rate through entrance mm Millimeter m n Mass flow rate through nozzle MT n N N N s Metric ton Rotational speed Newton pump operating speed pump specific speed N ss pump suction specific speed NPSH OD Net positive suction head Outer diameter v

17 OPC P P Peff P i P p P t P v Q Overall propulsive coefficient Pump discharge pressure Longitudinal Center of Gravity Effective power Static inlet pressure Power required to drive the pump Total Power Vapor pressure Flow rate Q BEP pump flow rate at best efficiency point R air Total air resistance R f Rn RPM R T shp t TCB T e T G T N U m U t V 1 V a VCB Vel V i V j Air friction resistance Reynold s Number Revolutions per minute Total resistance Shaft horse power thrust deduction fraction Transverse center of buoyancy Effective thrust Gross thrust Net thrust Axial velocity of water entering the impeller Impeller tip speed Bottom average velocity Speed of advance Vertical center of gravity Velocity Water inlet velocity water jet exit velocity vi

18 V pi Water velocity at pump entrance V ri V s V t V w W WD W e Relative inlet velocity Ship velocity Impeller tip speed wake velocity Underwater volume Underwater volume Ship weight Work done Work done to elevate water Greek letters α β pump shaft vertical inclination Deadrise angle ε ΔΕ Ratio between entrance and exit areas of diffuser Change in energy Δ T Loss in forward thrust ζ Inlet loss coefficient η D η D Diffuser efficiency Quasi propulsive efficiency η H Hull efficiency η j Jet efficiency η n η p η r η t θ λ λ k μ Nozzle efficiency pump efficiency Relative rotational efficiency Transmission efficiency Steering angle Wetted length to beam ratio Keel wetted-length ratio Velocity ratio vii

19 π ρ ρ a Ratio of circumference to diameter of a circle Mass density of water Mass density of air σ H Thorma s parameter τ υ φ Trim angle Kinematic viscosity of water pump shaft horizontal inclination ψ ω Nozzle loss coefficient Taylor wake factor Infinity viii

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