Transcript Fluid Power Resistance - University High School

Resistance in Fluid Systems
Mr. Andracke
Principles of Technology
Daily Objectives
Each student will be able accurately
complete the following:
Understand and define the types of drag
and its applications
• Define laminar and turbulent flow
• Explain viscosity and how it is measured
•
Drag
What is Drag??
Drag
Drag is defined as the force found
when a solid object moves through a
fluid, also there is a force that
opposes the motion.
Example: When an airplane moves through
air.
What is another example of drag?
Understanding Drag
Thrust = Drag
Drag is an
aerodynamic force
that resists the
motion of an
object moving
through a fluid.
Laminar Flow
Laminar or streamlined flow is a slow,
smooth flow over a surface, in which the
paths of individual particles do not cross.
These particle follow theoretical layers of
fluid.
Laminar Flow creates frictional drag
What is an example of Laminar Flow on an object?
Turbulent Flow
Turbulent flow is an irregular flow that is
disrupted causing fluid to move in
different directions.
Turbulence causes a wake behind a moving
object.
Turbulent flow creates pressure drag
What is an example of Turbulent Flow on an
object?
Frictional Drag
Frictional Drag is produced by the
friction between successive or
laminated layers of fluid, with
increasing speed away from the
surface.
When does Frictional Drag take place?
Pressure Drag
The pressure difference found in
turbulent flow causes a force to act
on the object in the direction
opposite its relative velocity.
When does Pressure Drag take place?
Understanding Drag
Both Frictional and Pressure Drag
increase as the speed of an object
increases.
When turbulence is created, pressure
drag increases more rapidly than
friction drag.
Viscosity
What is Viscosity??
Viscosity
Friction between two solid surfaces
causes a resistance to movement
between the surfaces.
Viscosity is the property of a fluid
that describes its internal friction.
Viscosity
What are some items that might
have a higher viscosity? A lower
viscosity?
Viscosity
Different fluids resist motion
differently, and therefore have
different viscosities.
Gum and Molten Lava have high viscosities
Air and Water have a much lower viscosity
Review Questions
What is one type of drag and give an
example?
What is the main difference between
laminar and turbulent flow?
Explain viscosity and give an example.