Slowin' down I'm gettin' tired!
Slowin' down
And I envy you the valley that you've found
'Cause I'm midway down the midway
Slowin' down, down, down, down

("That Song About The Midway," by Joni Mitchell, 1969)

 

CENTRIFUGAL FORCE AND CENTRIFUGAL ACTION 

PTOA Readers and Students who are reading the PTOA Segments in the intended sequential order have been promised an explanation regarding how Centrifugal Action builds up the PV Pressure in a centrifugally-pumped liquid.

Who amongst the brilliant PTOA Readers and Students is surprised to learn that Centrifugal Force is one of the key agents that take part in Centrifugal Action?

 

Centrifugal Force is likewise harnessed to create the thrills for the crowds that attend Amusement Parks!

Without Centrifugal Force ...

 

Roller Coasters, Gravitrons, Tilt a Whirls, and even the high-flying circular swings on The Midway would not be amusing!

This PTOA Segment describes what Centrifugal Force is and how it is harnessed to create the Centrifugal Action that generates the thrills on the Midway.

And guess what?

Centrifugal Force also solved the big problem of how to build up the PV Pressure in liquids!

 

HOW CENTRIFUGAL FORCE IS CREATED

Centrifugal Force hangs out in the Universe and is generated any time an object is moving on a curved pathway.

When an object is moving on a curved pathway, Centrifugal Force invisibly originates from an invisible center of an invisible circle that would exist if the pathway could make a complete circle.

Yes Indeedo ...

The impact of Centrifugal Force on any object that is moving in a circle or arc would feel like it is being pushed outward.

In fact, the object would be flung radially outward from the center of the circle if no counteracting force is around to keep it from doing so.

For example:

The car shown in the nearby graphic is driving around a curve.

Centrifugal Force is shown as a red arrow pushing on the car.

The driver of the vehicle must steer the vehicle more consciously around the curve so that Centrifugal Force does not cause the vehicle to cross over the dotted yellow line and into oncoming traffic or else ... depending on the car's speed ... the car might even "spin out of control."

The red arrow which represents Centrifugal Force  is correctly drawn as shown.

It is easy to Imagine the origin of the red line to be the center of an invisible circle that would be on the passenger side of the turning car.

The children on the Merry Go Round shown in the nearby photo are feeling the impact of Centrifugal Force on their backsides.

Centrifugal Force is created when the Merry Go Round is made to spin around.

Although they appear to be seated, once the circular platform of the Merry Go Round is spinning, the children are moving in a circle which has the blue vertical radius.

Ergo, the children meet the definition of "objects moving on a curved pathway" ... and thus Centrifugal Force is created.

The children feel the Centrifugal Force pushing them outward from the  center of the spinning Merry Go Round.

See the vertical and circular metal bars in the photo?

Without those devices in place, the children would be flung outward and off of the Merry Go Round by Centrifugal Force.

Hey! That would not be very amusing!

The gal in the nearby photo does not look like she's having a very good time!

As they grow older, these children will seek greater thrills in an Amusement Park.

Creating Centrifugal Force is the key operating principle for most of the not-so-cheap thrills that can be found on a Midway.

 

One of the commonly found carnival rides that relies on the impact of Centrifugal Force to encourage fine folks to depart with hard earned cash is The Centrifuge (aka The Gravitron).

Eagar riders line up in a circle with their backs supported by the vertical support wall of a cylinder.

The cylinder is spun around.

Once spinning begins, Centrifugal Force smashes the riders against the vertical support ... sound like good time?

Wait! There's more fun!

When the floor of The Centrifuge starts retracting, the riders are thankful for the Centrifugal Force that keeps them plastered against the spinning wall of The Centrifuge because that prevents them from likewise falling downward.

Possibly the most common use of Centrifugal Force to create screams and thrills at the Amusement Park is the Roller Coaster.

The train of linked cars in a true roller coaster is not electrically or otherwise powered by the track they run on.

A true roller coaster is powered by how the design of the coaster uses gravity and creates Centrifugal Force.

Without Centrifugal Force, the linked cars shown in the nearby roller coaster photo would fall off the track due to gravity.

The train of cars does not fall off the track because Centrifugal Force ... originating from the middle of the circle ... is pushing outward and keeping the train adhered to the track while it completes the curves.

It is not hard to figure out that the speed of the moving object on the circular pathway ...

in this case the train of cars moving on the circular roller coaster track ...

is directly related to how much Centrifugal Force is created!

The faster the object is moving in circular motion, the greater the amount of Centrifugal Force created!

Heck ...  PTOA Readers and Students already know that because they have read PTOA Segment #170 .

So PTOA Readers and Students already know that increasing the  rpms of a Centrifugal Pump with a Variable Speed Driver will increase the TDH that the Centrifugal Pump creates.

 

 

Otherwise stated  ....

More Speed (RPMs) →

More Centrifugal Force Created  →

More Total Dynamic Head ...

which means more PV Pressure infused into the discharged liquid so that it can get to where it needs to go and do what is supposed to do!

 

CONVERTING CENTRIFUGAL FORCE INTO
CENTRIFUGAL ACTION WHILE INCREASING PV PRESSURE

The use of Centrifugal Force to inject the PV Pressure into "non-compressible fluids" ...

aka "liquids" ...

may seem boring and logical at first glance ...

yet a closer look reveals the concept to be a borderline miracle and example of Humankind genius!

Converting Centrifugal Force into the Centrifugal Action for the purpose of building up the PV Pressure in a liquid conquers the major dilemma that is specifically associated with the physical state known as "liquid."

As all PTOA Readers and Students learned in PTOA Segment #153 ...

Liquids are not compressible.

Unlike what happens with gases, decreasing the Volume of a liquid WILL NOT increase the PV Pressure of the liquid!

 

The dilemma of building up the PV Pressure in non-compressible fluids (aka liquids) is solved by combining a force found in the Universe and Humankind technology:

• Centrifugal Force is created by spinning the liquid around the vanes of a spinning Impeller.
• The liquid gains Velocity as it is flung radially outward from the Eye of the Impeller to the outer diameter of the Impeller.
• The Human-fabricated Volute ... which is the interior casing that surrounds the Impeller ... is specifically made to slow the Velocity of the radially-flung liquid down.
• The decreased Velocity of the liquid in the Volute is swapped for an increase in the PV Pressure. If that concept does not ring a bell then stop right here and reacquaint yourself with The PV Pressure ↔ Fluid Velocity Swap which was featured in PTOA Segment # 159.
• The liquid that is discharged from the Pump will be at a significantly higher Discharge Pressure.

PTOA Readers and Students ... Be Aware!

Creating Centrifugal Force alone would not build up the PV Pressure in a liquid!

Without the Volute, the liquid that spins off the outer rim of the Impeller would just radially fly into space.

 

The Volute of the Pump is intentionally fabricated to decrease the Velocity of the liquid and begin the swap of decreased Velocity into increased PV Pressure.

Ergo ...

 

The created Centrifugal Force PLUS the specially-fabricated Volute work together to generate the  Centrifugal Action that is needed to increase the PV Pressure in a liquid via the PV Pressure ↔ Fluid Velocity Swap.

 

SECOND VERSE ... SAME AS THE FIRST!

The PTOA Department of Redundancy Department shall repeat the steps and conditions that are essential to creating the Centrifugal Action that makes it possible to build up the PV Pressure in a liquid:

The pump's Suction Line piping and the Pump Suction/Inlet on the pump casing are specifically designed and bolted together such that the pumped liquid is fed directly into the Eye of the Impeller at the pump's Suction/Inlet Pressure.

The Impeller spins because it is attached to a rotating Driver of some type.

The Driver might be an electric motor or a turbine powered by steam or some hydrocarbon fuel. 

The varying size of the blue dots in the nearby Centrifugal Pump graphic represent the increasing PV Pressure in a liquid that is being pumped by a Centrifugal Pump.

A small blue dot shown at the labelled "Fluid Inlet" is at the Pump Suction/Inlet Pressure.

In Real World jargon the "Fluid Inlet" is called the Pump Suction/Inlet.

The diameter of the blue dots increases as the liquid is spun away from the outer rim of the Impeller and enters the "Diffuser Casing" section of the Volute.

The Volute captures the speedy liquid that has been radially spun outward from the Eye of the Impeller and is designed to swap the liquid's Velocity for an increase in the PV Pressure.

The liquid exits the pump at the labelled "Fluid Outlet" which in  Real World jargon is called the Pump Discharge/Outlet.

 

The Discharge Pressure at the Pump Discharge is always greater than the Suction Pressure at the Pump Suction because the Centrifugal Force supplied by The Universe and the specifically Human-made Volute have worked together to generate the Centrifugal Action that makes that desirable outcome happen.

Voila!

Humankind has solved the problem of building up the PV Pressure in liquids by creating Centrifugal Action from Centrifugal Force and Volute-fabricating expertise.

Makes you proud to be a Human, doesn't it?

 

TAKE HOME MESSAGES:  Liquids are essentially "non-compressible" which means that simply decreasing their Volume will not generate an increase in the PV Pressure as will happen with gases or vapors.

Human beings solved the problem of building up the PV Pressure in large volumes of liquid by using the technology of Centrifugal Action.

Centrifugal Action combines the Centrifugal Force that exists in the Universe with human expertise in Volute fabrication to build up the PV Pressure in liquids via the PV Pressure ↔ Fluid Velocity Swap.

Centrifugal Force:

• Will be generated any time an object is moving in a circular motion.
• Impacts the moving object as a force that will push the object radially outward from a center of an imaginary circle.
• Will be greater when the object is moving faster in the circular motion and vice versa.

Centrifugal Force in a Centrifugal Pump is generated when the vane on a spinning Impeller radially flings a liquid outward from the center to the edge of the Impeller.

The Human-Made Volute of a Centrifugal Pump converts the Velocity of the liquid that is spun and flung outward by Centrifugal Force into the PV Pressure via the PV Pressure ↔ Fluid Velocity Swap in a specially designed Diffuser Section of the Volute.

©2017 PTOA Segment 0173
PTOA Process Variable Pressure Focus Study Area
PTOA PV Pressure Rotating Equipment Focus Study

 

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