-bernoulli principle in fan-

In summary, the fan will start up faster at the bottom of the fan because the air is moving faster. The Bernoulli principle is involved in this. The higher pressure is found at the top of the fan because the air is moving slower.
  • #1
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----bernoulli principle in fan----

when a fan is started, why is there more air flow at the bottom of the fan and not at the upper region of fan...:confused:

>>Also explain if bernoulli principle is involved in this


thx an regards

arun
 
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  • #2
When a fan is started?Explain what time interval do you think of.
Probably,the effect has something to do with low rotating speeds of various
parts of a fan during the start-up phase.
 
Last edited:
  • #3
And what kind of fan?
 
  • #4
arunk8186 said:
when a fan is started, why is there more air flow at the bottom of the fan and not at the upper region of fan...:confused:

>>Also explain if bernoulli principle is involved in this


thx an regards

arun

Arun,
tell me bottom refers to center? and upper refers to tip of the blades? the fan axis is verticle or horizontal?
I ll get you correct answer.
 
  • #5
i mean a ceiling fan...by bottom i mean the region below the blades (may be the the entire area where we feel cool air ) and by upper region, i mean the area above the blades...

thx
 
  • #6
because when the air passes blades, air gets kinetic energy added from blades to it and moves faster than the suction side air.

Faster moving air makes you feel cool.

I hope, now you yourself can apply bernoulis eqn.

U R FROM TAMILNADU?
 
  • #7
@ ramesh
thanks for ur reply ...ok i agree that the surroundin air gains kinetic energy ...we also know from bernoulli that as velocity increases,pressure decreases.
Now my question is how do we relate this ...in which region is there higher and lower pressure?? and y don we feel the cool air at the upper region of the ceilin fan?

yes sir, i am from Tamil Nadu ...nice seein u . BTW whr r u from in TN

regards,

arun
 
  • #8
arunk8186 said:
@ ramesh
thanks for ur reply ...ok i agree that the surroundin air gains kinetic energy ...we also know from bernoulli that as velocity increases,pressure decreases.
Now my question is how do we relate this ...in which region is there higher and lower pressure?? and y don we feel the cool air at the upper region of the ceilin fan?

yes sir, i am from Tamil Nadu ...nice seein u . BTW whr r u from in TN

regards,

arun

Replied in your PM.
 
  • #9


I presume fan is a room cooling fan with no duct or cowl. If it is close to a table top or floor then that surface will have a partial ducting effect for airflow from bottom part of fan where that restriction will reduce the dispersion, mixing, and thus slowing of volumes of air in that region. The moving air will tend to follow close to a surface (see Coanda Effect). Bernoulli effect can be demonstrated at that surface eg by an open book or small pile of paper sheets just as wind from an open window will scatter papers from a desk.

From Darmog
 

1. What is the Bernoulli Principle?

The Bernoulli Principle is a fundamental concept in fluid dynamics that states that as the speed of a fluid increases, the pressure exerted by the fluid decreases. This principle is based on the law of conservation of energy, which states that the total energy of a closed system remains constant.

2. How does the Bernoulli Principle apply to fans?

In the context of fans, the Bernoulli Principle explains how the blades of the fan push air in one direction, causing a decrease in pressure behind the blades. This decrease in pressure creates a pressure difference between the front and back of the fan, which in turn causes air to flow from the back to the front.

3. What factors influence the Bernoulli Principle in fans?

The Bernoulli Principle in fans is influenced by several factors, including the speed of the fan blades, the shape and angle of the blades, and the density of the fluid (air) being moved. These factors can also be adjusted to control the amount of air flow and the direction of the air flow from the fan.

4. How is the Bernoulli Principle used in designing fans?

The Bernoulli Principle is a key concept used in the design of fans, as it allows engineers to create efficient and effective fan blades that can move air with minimal energy input. By understanding how the Bernoulli Principle works, fan designers can optimize the shape, size, and speed of the blades to achieve the desired air flow and pressure difference.

5. Are there any limitations to the Bernoulli Principle in fans?

While the Bernoulli Principle is a useful concept in understanding how fans work, it is important to note that it is not the only factor that influences air flow in fans. Other factors, such as air viscosity and turbulence, also play a role and can affect the performance of fans. Additionally, the Bernoulli Principle applies to ideal fluids, which may not always accurately represent real-world conditions.

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