250 likes | 507 Views
Introduction to Fluid Mechanics. Bellagio Fountain. Lecture 9: Introduction to Fluid Mechanics Approximate Running Time - 33 minutes Distance Learning / Online Instructional Presentation Presented by Department of Mechanical Engineering Baylor University Procedures:
E N D
Introduction to Fluid Mechanics Bellagio Fountain
Lecture 9: • Introduction to Fluid Mechanics • Approximate Running Time - 33 minutes • Distance Learning / Online Instructional Presentation • Presented by • Department of Mechanical Engineering • Baylor University • Procedures: • Select “Slide Show” with the menu: Slide Show|View Show (F5 key), and hit “Enter” • You will hear “CHIMES” at the completion of the audio portion of each slide; hit the “Enter” key, or the “Page Down” key, or “Left Click” • You may exit the slide show at any time with the “Esc” key; and you may select and replay any slide, by navigating with the “Page Up/Down” keys, and then hitting “Shift+F5”.
Introduction Dr. Carolyn Skurla Speaking
Aerodynamics Forces On An Airplane • What causes drag and lift? ldaps.ivv.nasa.gov/physics/lift.html
Drag • Drag is a function of friction • F = drag force • CD = drag coefficient • = density of the fluid • A = characteristic area • depends on body shape • v = free-stream velocity
Characteristic Area • The shape of the silhouette of the object • If you were a molecule of water flowing toward the object • And there was a light behind the object • What would the object look like to you?
L d Characteristic Area • Cylinder with fluid flow perpendicular to length of cylinder?
L Characteristic Area • Cylinder with fluid flow parallel to length of cylinder? d
Drag On A Cylinder - Why? No Flow Separation Stagnation Point Stagnation Point
Friction, that’s why! Drag On A Cylinder
Better streamlining of cars over the years Lower drag force & better fuel efficiency! Why Do We Care About Drag?
Example Of Friction http://www.dfrc.nasa.gov/gallery/photo/SR-71/
Fluid Exerts a Force • Drag -> Acts in the direction opposite to the motion of the object. • Lift -> Acts at right angles to the drag. (http://www.titleist.com/technology/aerodynamics.asp)
Example of Lift • Lift caused by pressure differential between top and bottom of wing. ldaps.ivv.nasa.gov/physics/lift.html
How Does a Curveball Work? • A spinning ball curves in flight • Magnus effect • Stitches are NOT required to make a baseball curve http://popularmechanics.com/science/sports/1997/4/breaking_pitch/print.phtml
Lift On A Golf Ball • How does a golf ball generate lift? (www.titleist.com/htm/tech/aero_main.asp)
Why are Golf Balls Dimpled? Dimples No Dimples (www.titleist.com/htm/tech/aero_main.asp)
Drag Force on Dimpled vs. Smooth Golf Balls • Dimpled golf balls generate less drag! • Increases angle of separation for transition to turbulence. (www.titleist.com/htm/tech/aero_main.asp)
Lift Force on Dimpled vs. Smooth Golf Balls • Backspin generates lift! • Dimpled golf balls have slightly improved lift. (www.titleist.com/htm/tech/aero_main.asp)