What determines ceiling fan airflow? [4 crucial parameters]
From Superfan, India’s first super energy efficient ceiling fan
The primary use of ceiling fans is to offer the desired thermal comfort by delivering sufficient airflow. There is a misconception of relating airflow to only the speed of a fan (RPM). Though, it is true that when the speed (RPM) of a fan increases by 10%, the airflow increases by 10%. Explore fan laws.
But the speed of a fan is not the only parameter that influences the airflow, and it is wrong to compare two fans by their RPM alone. There are other parameters of the fan design such as blade angles, blade size, blade area, number of blades. Also, the installation of a ceiling fan with proper placement and clearance impacts airflow.
Blade angles
The blade design is usually governed by the angle of attack, blade twist, and blade pitch. Designers play with these angles to develop a shape that delivers the required performance.
Blade size
The blade size is the length of the blade (It is typically the diameter of the fan minus the diameter of the motor). Increasing the blade length by 10% increases the airflow by 33% and the power consumed by 50%. The increase in power consumed may require a stronger motor so there is a trade-off for increasing the length of the blade. The operational RPM of the fans decreases with the increase in the blade length, making it quieter.
Blade Area
The blade area is the area of the fan blade’s face that is meeting the air while the fan is rotating. An increase in blade area increases the airflow and the power consumed. A designer usually compensates for the losses in performance in this parameter elsewhere as the aesthetics determine the shape(area) of the blade.
Number of blades
The number of blades is correlated with the blade area, a certain blade area can be split into more than one blade depending on the aesthetics and cost. The increase in the number of blades reduces the RPM required, making the fan quieter for the same airflow. Typically, the ceiling fans have 3 blades as it is the optimal number for the cost and the performance.
How does Super Q ceiling fan of Superfan delivers higher airflow than regular fans while operating at a lower RPM?
The argument above has made this question irrelevant as RPM should not be used alone to compare two fans. The question must be changed to ‘how does Super Q deliver more airflow than a regular fan?’ The answer would be the shape of Super Q blade is more efficient in moving air than a regular fan blade so for the same energy more air flow is delivered. Explore the differences between high speed and high flow ceiling fans now!
| Parameter | Values | |||||
| Span (mm) | 24″ (600mm) | 36″ (900mm) | 42″ (1050 mm) | 48″ (1200mm) | 56″ (1400mm) | 60″ (1500mm) |
| Typical speed (RPM) | 420 | 320 | 280 | 270 | 220 | 200 |
| Typical input power (Watts) | 20 | 25 | 25 | 35 | 30 | 35 |
| Air Flow (m3/min) | 120 | 150 | 210 | 260 | 300 | 330 |
| Service Value (m3/min/ watt) | 6.0 | 6.0 | 8.4 | 7.4 | 10.0 | 9.4 |
| Rated Supply | 230Vac (48Hz-52Hz) | |||||
| Power parameter | >0.9 |
Talk to our fan experts to help choose the right ceiling fan for you.
Contact us at 1800 425 78737 or email at superfan@superfan.in
2 thoughts on “What determines ceiling fan airflow? [4 crucial parameters]”
Hello, could I ask how to measure the effective area of the ceiling fan in order to determine the airflow of the fan? Thank you
We use the anemometer measurement to measure the airflow, if the airflow is below a certain cut-off value the radial measurement is stopped. This radius is the coverage of the fan, given that it mounted at the ideal height of 9 feet from the floor.