Download Applications of Bernoulli`s Principle

Applications of Bernoulli’s
Principle
Georgia CTAE Resource Network
Curriculum Office
Philip Ledford and Dr. Frank Flanders
Daniel Bernoulli
Daniel Bernoulli was a Dutch-Swiss mathematician who is most known
for his work in fluid mechanics and for his boom Hydrodynamica.
Bernoulli came up with the equitation
where:
– is the fluid flow speed at a point on a streamline,
– is the acceleration due to gravity,
– is the elevation of the point above a reference plane, with the
positive z-direction pointing upward — so in the direction opposite to
the gravitational acceleration,
– is the pressure at the point, and
– is the density of the fluid at all points in the fluid.
Bernoulli’s Equation
What does it mean?
In a simplified non-mathematical explanation, Bernoulli’s equation
basically means that if velocity (the speed of motion) of a fluid
increases, the pressure within (the force per unit area applied to
an object) the fluid decreases.
Bernoulli’s principle is used in aerodynamics and help explains how
airplane get lift, and how race cars stay on the ground. It also has
uses in lots of different machines such as a Hozon for agricultural
use.
Hozon – Siphon Mixer
A Hozon siphon mixer is used agriculturally
to fertilize plants.
This device operates somewhat with
Bernoulli’s principle.
Water flows through the device at a certain
velocity. As you can see the water flows
over tube where fertilizer is projected into
the water.
Hozon – Siphon Mixer (con’t)
This is where Bernoulli’s principle steps in.
Because the water is flowing over the top
of the fertilizer tube it creates pressure
around the stream of moving water.
This pressure around the stream of water
causes the fertilizer to be projected
upwards towards the stream of water.
Hozon – Siphon Mixer (con’t)
Why doesn’t the water just
spray into the fertilizer tube?
The pressure of the stream is very
low since it’s velocity is very high.
But, the velocity around the out side
of the stream of water is very low,
thus causing the pressure outside
the stream of water to be very high.
The high pressure that is projecting
fertilizer into the water doesn’t allow
the water to enter the fertilizer tube.
Racecars!
Notice the shape of the
spoiler.

The spoiler starts out thin
and gradually curves
upward.
This causes the velocity to
decrease and pressure to
increase on the top.
Racecars designs such as the ones the perform in the Indianapolis 500 use Bernoulli’s
principle to keep the car on the ground, and allow the car to make sharper turns.
Racecars! (con’t)
The spoiler of the car is shaped so that the velocity of air on the top of the spoiler is
moving slower, thus creating more pressure on the top of the car pushing the car
downward. The velocity of air on the bottom of the spoiler is much faster, thus having less
pressure pushing upward on the car.
Airplanes
Notice the shape of the
airplanes wings.
They are shaped
opposite of a racecars
spoiler.
The top of an airplane’s wings are shaped so that the velocity of air moves faster
over the top and slower on the bottom. Since the velocity of air is faster on top that
means the pressure on top is low. The velocity of air is slower on the bottom so the
pressure on bottom is greater helping give lift (the force that pulls an object outward,
or upward.) to the airplane keeping it up in the air.
Airplane Wing
The top of an airplane’s wing is shaped so
that the velocity of air moves faster over
the top and slower on the bottom. Since
the velocity of air is faster on top that
means the pressure on top is low.
The velocity of air is slower on the bottom
so the pressure on bottom is greater
helping give lift to the airplane keeping it
up in the air.
* The same concept of low velocity and high pressure on the bottom of an
airplane’s wings also applies to the wings of flying birds.
Summary
What did we learn?
Daniel Bernoulli was a Dutch-Swiss mathematician who came up
with the principle of fluid mechanics known as Bernoulli’s Principle.
Bernoulli’s principle basically states that as a fluid’s velocity
increases the pressure within that fluid decreases.
Summary (con’t)
Devices such as Hozon siphon mixers use Bernoulli’s principle to
cause fertilizer to mix with water by the pressure of the water it is
being mixed with.
Racecars use a spoiler shaped so that pressure stays on top of the
car holding down.
Airplane wings are shaped opposite of racecars to have pressure on
the bottom of the wing to give it lift.