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EN400 – Principles of Ship Performance

EN400 – Principles of Ship Performance. An Introduction to Naval Architecture (Alias “Boats”) Associate Professor Paul H. Miller. INTRODUCTION. Course Objectives (Why Study Boats?) Personal Introductions Name Major Service Selection Syllabus/Course Policy

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EN400 – Principles of Ship Performance

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  1. EN400 – Principles of Ship Performance An Introduction to Naval Architecture (Alias “Boats”) Associate Professor Paul H. Miller

  2. INTRODUCTION • Course Objectives (Why Study Boats?) • Personal Introductions • Name • Major • Service Selection • Syllabus/Course Policy • Lecture #1! - Engineering Fundamentals

  3. Some of my projects…

  4. Plots, Graphs, and Sketches (1.1) ENGINEERING FUNDAMENTALS • Plots or Graphs - Generally the most effective format for displaying and conveying the interrelation of experimental variables. • Sketches - Quick and informal method of sharing ideas with others or clarify concepts for yourself. Free body diagrams (FBDs) are an example.

  5. Plots and Graphs (1.1) ENGINEERING FUNDAMENTALS

  6. Sketches (1.1) – A Free Body Diagram ENGINEERING FUNDAMENTALS

  7. Plots, Graphs, and Sketches (1.1) ENGINEERING FUNDAMENTALS • Means of Communicating Ideas Concisely • Axes • X-axis (horizontal (independent variable)) • Y-axis (vertical (dependent variable)) • Divide major axes into divisions of 1, 2, or 5 times 10 to the nth power • Label with words, symbols, and units • Minor axes should be distributed evenly

  8. Area Under and Instantaneous Slope of a Curve (1.3) ENGINEERING FUNDAMENTALS Dependent

  9. Units (1.4) ENGINEERING FUNDAMENTALS   the unit system used in EN200

  10. miles 1 hour 8 x 30 min x 60 min hour Engineering Fundamentals Unit Analysis (1.4.1) • A “fool proof” method of determining the correct units! • Example: Speed x Time = Distance = 4 miles

  11. Significant Figures (1.5) ENGINEERING FUNDAMENTALS • The number of accurate digits in a number • Example: 2.65 has 3 significant figures • Example: 10 has 1 or 2 , 10.0 has 3 • Example: 0.25 has 2 (note 0.25, not .25!) • Multiplication / Division: Use the same # of • significant figures as the number with the least # of significant figures • Example: 20 x 3.444 = 69 • Addition / Subtraction: Use the same # of • decimal places as the number with the least # of decimal places • Example: 3.6 + 1.212 = 4.8

  12. Forces, Moments, and Couples (1.7) ENGINEERING FUNDAMENTALS • FORCE - a vector quantity (i.e. a magnitude and a direction) • MOMENT – a force times a distance with respect to a given origin (M=FxD) • COUPLE - A special case of moment causing pure rotation and no translation

  13. ENGINEERING FUNDAMENTALS Static Equilibrium 1.7.5 If an object is neither accelerating or decelerating then it is because… • Sum of the forces = 0 • Sum of the moments = 0 • Why? • F=ma • (This is very important in “hydrostatics”)

  14. Hydrostatic Pressure 1.7.6 • “Pressure” is the amount of force applied to a given area (p=F/A) • In English units it is pounds/sq. ft. or pounds/sq. in., or “psi” Air pressure is ~ 15 psi. At 440 ft below sea level it is ~ 195 psi!

  15. Question: If a ship follows this path, at a constant speed, is it static or dynamic? Quick Physics Review Static: No acceleration Dynamic: Has acceleration

  16. ENGINEERING FUNDAMENTALS The Mathematical First, Second and Third Moments (1.7.7) • These integrals are used in mathematical descriptions of physical problems Where: s = some distance db = some differential property = Summation

  17. ENGINEERING FUNDAMENTALS The Mathematical First, Second and Third Moments (1.7.7) • In Naval Architecture: • “b” could represent length, area, volume, or mass • “s” is a length or distance • First Moment of Mass  • Second Moment of Area 

  18. ENGINEERING FUNDAMENTALS Weighted Averages (1.7.7) In Naval Architecture we use the simplified form: to find the Longitudinal Center of Flotation (LCF), Longitudinal Center of Buoyancy (LCB), Center of Gravity (LCG, TCG, VCG)

  19. Translational and Rotational Motion (1.8) ENGINEERING FUNDAMENTALS • A ship (or plane) has 6 degrees of freedom (DOF) • Three are Translational • Heave (z) (up and down) • Sway (y) (side to side) • Surge (x) (fore and aft) • Three are Rotational • Yaw (z) • Pitch (y) • Roll (x)

  20. Bernoulli’s Equation • P = pressure • r = fluid density • V = fluid velocity • Z = depth Along a line of equal energy (a streamline) in a fluid, the above is a constant.

  21. ENGINEERING FUNDAMENTALS Bernoulli Equation (1.9) • total pressure is constant in a fluid, if: • inviscid flow (no viscosity) • incompressible flow • steady flow This gives us hydrostatic and hydrodynamic pressure. These are the water loads on the vessel.

  22. Pressure Prediction • Vertical pressure supports the vessel (lift versus weight) • Horizontal pressure is thrust and drag These are the same as an aircraft!

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