How does a fan work?
How exactly does a fan work. The Science of Wind Energy
Have you ever been in front of a fan on a hot day and thought, “How does a fan work? And this thing cool me off?” Sounds easy — you flip the switch, blades start to whirl, and boom, you’ve got a refreshing breeze. Hidden beneath this common household appliance is an incredible world of physics. In this blog post, we’ll break down how a fan works with kid-friendly vocabulary and concepts, so you can get to the heart of what makes that cool breeze so magical.
Join us to learn about the promising new technologies and how they are being used to make AVs safer and smarter. And how does a fan work?
What is an RAISE Fan
A fan is literally a machine with rotating blades. These blades move air, generating a cooling breeze that either makes us feel cooler or helps ventilate a room. Fans take many forms — from little ones built into your portable computers to huge ones used in factories — but all operate on the same fundamental principles.
How does a fan work? And to cool people off?
The Major Components of a Ceiling Fan
Before we dive deep into some physics, though, let’s first familiarize ourselves with the key components of a standard electric fan.
1.Electric Motor –
The brains of the fan. This is because it uses electrical energy to create mechanical motion.
2. Blades (or impellers) –
Blades are the parts that are spinning around and physically moving the air.
3. Housing (the frame or skin) –
This piece ties everything together and can heavily impact airflow.
4. Control System –
The buttons on your unit, or a remote, that operate the rollers and adjust speed and power.
How does a fan function, anyway? — Julie Conley, National Organizing Coordinator
Stage 1: Electric Power to Movement – The Motor
When you connect a fan to an electric circuit and turn it on, electricity moves into the electric motor. The motor operates on the principle of electromagnetism — one of the four fundamental forces that is underlying all of physics. How does a fan work?
Inside the motor, wire coils and magnets grab on to one another. When an electric current flows through the wire, it generates a magnetic field. This magnetic field interacts with other magnets in the motor, causing a part known as the rotor to rotate.
This motion around an axis is known as rotational kinetic energy — the energy of something that spins. Since the fan blades are attached to the rotor, as the rotor spins the blades also.
Step 2.Moving Air - Newton's Laws in Action
Once the blades start to spin, they begin to push air. This is when Newton’s Third Law of Motion plays a role.
“For every action, there is an equal and opposite reaction.” The blades of a fan are usually pitched the same way (with a slant), like wings of a plane. As they spin, they cut through the air and push it forward. In turn, the air moves — that’s the breeze you feel.
This is also a function of Bernoulli’s Principle – Bernoulli’s principle explains how air pressure is altered when air moves faster. The spinning blades are causing the air to move, but also the movement of air causes a change in pressure that creates a spot of low pressure. Air will naturally flow from a higher pressure to a lower pressure, affecting where airflow goes. How does a fan work?
Step 3. Why It's Cool - Evaporation and Heat Transfer
You may be asking: “If the fan does not cool air, why do I feel cooler?”
That’s a great question – and the answers physics presents is elegant.
Here is what is happening:
Your body is always giving off heat.
On a hot day, your skin sweats to lower your body temperature.
The air from fan increases evaporation of the sweat.
Evaporation is a cooling process – it is removing heat from your skin.
In the world of physics, we refer to this process as heat transfer – the fan is helping to move heat away from your body faster, so you perceive a cooler sensation. Although the air temperature isn’t less, your body perceives a cooler sensation because it is transferring heat away from your body more quickly.
Building upon the idea of wind chill, wind, and temperature; let’s look at:
Step 4: Controlling Air Movement - Speed and Blade Configuration
Fans typically can be operated at different speeds and fan designs can vary significantly. How does a fan work? When you increase the speed of the fan, the motor spins faster, meaning the blades will displace more air. Two of the factors that influence how much air the fan will be able to move include the following:
The rate of rotation (measured in revolutions per minute, or RPM)
The size and shape/design of the blades
The angle (pitch) of the blades
Regardless, the fans’ ability to produce airflow can come down to the combined influence of all these factors, and airflow is measured in cubic feet per minute (CFM).
More speed → means faster blade spin → means more air → means better breeze. How does a fan work?
Types of Fans - All Based on Same Physics
There are countless fans out there to use, and many types available, but they all use the same base physics. Here are a few common fan types:
Axial Fans -
Typically like most table-fans, axial fans have blades that rotate around a central hub and push displaced air in a straight path (as you can see).
Centrifugal Fans -
These blow air outward (there are many instances like vacuum cleaners, or air conditioners where the fan will move extreme air outward). How does a fan work?
Bladeless Fans –
Similar to Dyson fans. It has motor and blades hidden inside a ringed frame that forces air through the frame using air multiplication.
Regardless of the shape, it’s still electromagnetism + motion + differential air pressure = wind
Fun Physics Titbit: Fans in Space?
You might be shocked to learn that a fan won’t do what it normally does in outer space. Why not?
Because there is no air in outer space! A fan needs air molecules to push, in order to create a breeze. When there is no air — the blades spin — and nothing happens. This shows how much the medium (air) matters in the physics of fans.
Conclusion –
The Science of a Fan in Layman’s Terms
Now you can understand how does a fan work and Behind theory of Physics. A fan converts electrical energy in to spinning motion with a motor (due to electromagnetism);
The spinning blades push air forward, which creates a breeze (due to Newton’s laws and a pressure difference); and, The airflow assists the evaporation of your sweat, which cools you down (due to the physics of heat transfer);A range of different designs and speeds produces different amounts of air.
Simple, no? How does a fan work? Yet, it is all powered by some incredible physics. How does a fan work?
Frequently Asked Questions: The Physics of a Fan
Q1: Is a fan actually cooling the air?
A: No, a fan does not cool the air, it generates air movement which ultimately helps move the sweat off of your body. The process of evaporation removes heat from your body and therefore you feel cooler while air temperature remains consistent.
Q2: What is the principle of how a fan blade pushes air?
A: A fan blade pushes air because of Newton’s Third Law of Motion — for every reaction there is an equal and opposite reaction. As the blades push the air forward, the air can do nothing but move in response.
Q3: What is rotational kinetic energy?
A: It is energy for something that is spinning. In a fan, the blades are spinning because of the motion of the fan’s motor. The spinning motion of the blades is rotational kinetic energy.
Q4: How does electromagnetism fit into the function of a fan?
A: Electromagnetism is the force behind the motor in the fan. As electricity flows through coils of wire in the motor, it creates a magnetic field which in turns causes the rotor to spin, turning the blades.
Q5: Why are fan blades angled or pitched?
A: Fan blades are angled or pitched so that they can change the direction of the airflow out of the fan more effectively. The pitch of the fan blades allows the blades to push more air as they turn, thus creating a stronger breeze or flow.
Q6: What is Bernoulli’s Principle and how does it apply to fans?
A: Bernoulli’s Principle states that when the air moves faster, it creates less pressure. When fan blades move the air quickly, an area of low pressure is created and thus creates airflow from the higher pressure area to the lower pressure area.
Q7: Can a fan work in a vacuum or in space?
A: No a fan cannot work in a vacuum. A fan relies on moving air, and in a vacuum of space there are no air molecules to move at all.
Q8: How does a change in fan speed change air flow?
A: A change in fan speed actually increases the speed of the fan blades, which increases the amount of air moved by the blades. Increasing the air movement creates stronger airflow or a stronger breeze.
Q9: What is CFM in terms of fans?
A: CFM stands for Cubic Feet per Minute, and is a measure of the amount of air the fan moves. A larger CFM means more airflow and often better cooling or ventilation.