# Calculating Torque for Fan Speed

• violin_writer
In summary, calculating torque for fan speed involves determining the rotational force applied to the fan blades. This can be done by multiplying the force applied to the blades by the distance from the center of rotation to the point where the force is applied. The resulting torque value is crucial for determining the fan's speed and power requirements. Additionally, factors such as blade size, shape, and air resistance must also be taken into account when calculating torque for fan speed.
violin_writer
Hello, I need figure out the torque is required to spin a fan blade at a certain speed. I know it doesn't particularly matter how big the fan is, but how heavy it is. I know a 1gm fan is much easier to turn than a 2gm fan.

Can anyone help me?

At a constant speed, it's not the weight that matters, it's the size of the fan (well, its design).

Get a fan curve from the manufacturer, this shows you the power required to drive the fan at a range of speeds.

...and the speed of the fan doesn't actually have a direct impact, it's the operating conditions: the pressure and airflow.

There are three Fan Laws or Affinity Laws that may help you get started:
http://www.nrmurphy.com/fans_laws.html

## 1. How do you calculate torque for fan speed?

Torque for fan speed can be calculated using the formula: Torque = Force x Radius, where force is the amount of energy exerted on the fan blades and radius is the distance from the center of the fan to the edge of the blades.

## 2. What units are used to measure torque for fan speed?

Torque is typically measured in Newton-meters (N·m) or pound-feet (lb-ft) for fan speed calculations.

## 3. How does torque affect fan speed?

The higher the torque, the faster the fan blades will rotate and the faster the fan speed will be. Similarly, a decrease in torque will result in a decrease in fan speed.

## 4. Are there any other factors that can impact torque for fan speed?

Other factors that can affect torque for fan speed include the weight of the fan blades, the type of motor being used, and any external forces acting on the fan, such as air resistance.

## 5. How can torque for fan speed be adjusted?

Torque for fan speed can be adjusted by changing the amount of force or the radius of the fan blades, or by altering the speed of the motor that is powering the fan. Additionally, using different types of fan blades or motors can also affect torque and fan speed.

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