Fan blade shapes

Material: The material used in industrial propellers or fan blades is generally fabricated steel, cast or fabricated aluminum, fabricated stainless steel or other exotic metals. Plastic propellers have become common, but typically only in commercial or residential fans. Fiberglass is also available for corrosion or chemicals resistance. Number of Blades: The number of fan blades is generally only limited by the size diameter of the propeller. Props will generally have as few as 2 blades, up to 16 blades.

Some even have an odd number of blades such as 3, 5 or 7. The most common are 4 and 6 blade props. Blade Shape: The shape of the fan blade can be almost anything from square to round to rectangular.

The corners are typically always rounded for greater efficiency and less noise. In most cases, large square blades are used to obtain the highest volume with the lowest noise. Blade Pitch Angle: The blade pitch angle is a critical factor in the overall performance of the propeller. In general, the greater the pitch angle, the slower the fan can turn. Some propellers or fan blades are made with adjustable blade pitch angles either set at the factory or adjustable while operating in-flight adjustable.

Additional Requirements Please attach any drawings or other information that may assist us. There are typically four criteria used in the design of propeller blades or fan blades. The material it is made from. The number of blades. The blade shape. The blade pitch angle.

fan blade shapes

What's it like to work with Cincinnati Fan? Our customers and reps describe their experience in less than 2 minutes.The size of an outdoor fan is based on the size of the fan blades. The blades are critical to the amount of cooling you can expect from your fan. Not only their size but also their number, shape, speed of rotation, even their angle can affect the cooling ability of an outdoor fan.

We discuss all of that here, plus the materials they're made of. A smart choice of fan blades can maximize the fan's air flow and cooling ability. It's good to know if the fan you want to buy will do a good job of cooling an area, or if it will just look good. Understanding a little about the fan blades can help you know that before you buy. Also, more and more ceiling fan retailers are making it possible for you design your own fan by choosing the fan's blades. You can avoid making a mistake if you just know a little about them, first.

The size of an outdoor fan is measured straight across from blade tip to blade tip. The longer and the wider the fan blades the more air they will move. The size of the area you need to cool will help determine the size of fan to use. The following outdoor ceiling fan size chart shows some typical outdoor fan sizes and their recommended areas for cooling. Fan size is based on the measurement of the outdoor ceiling fan blades.

This chart is just to give you a general idea -- the numbers are extremely flexible depending on the configurations of any one fan its CFM, efficiency and wattage and of any one area.

Large areas may require more than one fan. Rectangular, odd-shaped areas, or partially divided areas are best cooled by multiple smaller fans. This chart doesn't apply to wall-mount or standing fans. Most standing fans blades are simply not that large. Plus standing fans of comparable sizes generally move more air than ceiling fans.

To size wall mount fans and floor or standing fans, use the standards of CFM, efficiency and wattage, and follow this rule:.

How to Optimize a Propeller or Fan Design

To estimate how much airflow to look for in a fan multiply the area in square feet or square meters by 3 to 4 to estimate CFM or CMM. The fan's blades can maximize the fan's air flow. Its often better to use several smaller outdoor fans than one large fan.Hot Threads. Featured Threads. Log in Register. Search titles only. Search Advanced search…. Log in. Forums Engineering Mechanical Engineering.

JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding. Thread starter kach22i Start date Jul 13, Air or Water: I'm looking for information on fan and propeller shapes ducted and non-ducted which might lead to more quiet if not more efficient shapes. Noise is lost energy just as heat is lost energy in a mechanical system, right?

I have a thread which contains many bits of information for the context of this request. It also has many pictures which if you cannot see tell me and I'll repost all the links here. I'm no engineer, pretty pictures tell me a lot. However if you have recommended text books, graphs, charts or other information you feel you can share, please add it to this thread. Last edited by a moderator: May 3, Related Mechanical Engineering News on Phys. DaveC Gold Member. And cavitation.

Big problem in propellors. That's why they're curved. FredGarvin Science Advisor. Do realize that fan shape is an extremely active area of research. We are always looking for ways to tweak our fan blade designs to achieve exactly what you are asking about.

In regards to noise, the tip geometry is pretty much king. That's where you are sure to go supersonic and that is where the noise is generated.

For example, the forward swept tip is now the standard.

fan blade shapes

FredGarvin said:. I didn't get a chance to get down to Willow Run this time. I was bummed out. Anyways, there are certain things that fan design need to accomplish: - High thrust - Low weight - Low Noise - Structural integrity It's difficult to say exactly what each fan designer had in mind with each specific piece of geometry. As I mentioned before. That means noise. So pretty much any design is an effort to increase the efficiency and decrease the noise at the tips.

Industrial Fan Blades, Axial Fan Blades, or Propellers

From page 12 of the Random Picture thread in the O.All fan and compressor blades in a turbofan engine are airfoils, meaning they have an elliptical leading edge like a conventional propeller blade. Turbofan blades are also long and wide, giving them a large surface area. When 20 blades with a six-metre foot diameter are spinning at the same time, they can move around 1, kilograms 2, pounds of air per second, producing signifi cant thrust.

Ducted fans have the advantage of reducing a drag effect called wingtip vortices. When an elliptical wing cuts through the air, it leaves a spinning trail of air called a vortex.

That vortex increases drag, vibration and noise. Ducted fans prevent this and, as a result, are quieter, run smoother and can create the same amount of thrust with shorter blades.

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Fan & Propeller shapes: Sickle and Curved

Latest offer. Recent posts Why do rabbits have long ears? How do concrete mixers work?The pressure head of different types of fans with equal periphery speed of the wheel are compared in the capacity diagram below:. Centrifugal fans with forwarded blades are suited for application with higher air flow volumes and pressures. Axial propeller fans are more suited for applications with lower volumes and pressures.

fan blade shapes

In an axial fan the air flows in parallel to the shaft. It is common to classify axial fans upon their wheel like:. Axial fans are suited for relatively large volumes compared to pressure. In a centrifugal fan the air flows is in a radial direction relative to the shaft. Centrifugal fans can be classified by their wheel like:.

In a mixed flow fan the air flows in both axial and radial direction relative to the shaft. Mixed flow fans develops higher pressures than axial fans. In a cross flow fan the air flows in an inward direction and then in an outward radial direction. Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro.

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Axial and Propeller Fans In an axial fan the air flows in parallel to the shaft. It is common to classify axial fans upon their wheel like: C-wheel - Blades can be adjusted when running. High efficiency, small dimensions, variable air volume A-wheel - Blades can be adjusted only when the fan is standing still. High efficiency, small dimensions, adaptive to recommended air volume K-wheel - Blades can not be adjusted. Centrifugal fans Radial fans In a centrifugal fan the air flows is in a radial direction relative to the shaft.

Centrifugal fans can be classified by their wheel like: F-wheel - Curved forward blades. High efficiency, small dimensions, changing in pressure have little influence on pressure head. B-wheel - Curved backward blades. High efficiency, low energy consumption, changing in pressure have little influence on air volume.

Fan types and blade efficiency

Low noise emission, stable in parallel running. P-wheel - Straight backward blades. High efficiency, self cleaning, changing in pressure have little influence on air volume T-wheel - Straight radial blades. Self cleaning. Suitable for material transport Types of blades used in centrifugal fans are Straight steel plate paddle wheel Forward multi-vane multi-blade Backward turbo-vane The different blades can be characterized as shown in the capacity diagram below: Mixed flow fans In a mixed flow fan the air flows in both axial and radial direction relative to the shaft.

Cross-flow fans In a cross flow fan the air flows in an inward direction and then in an outward radial direction.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics.

It only takes a minute to sign up. How is the shape of the blades of an air fan determined? Trial and error, or is there a theory behind it?

What are they trying to maximize, volume of air dislocated per rotation? A combination of Computational Fluid Dynamics modelling how the air flows over the blade and Finite Element Modelling how the stresses in the metal behave.

Both of these are complex areas - and when they come to together you need a lot of expensive computers and some even more expensive engineers. Since the part of the blade moves slower the closer to the center, the angle of attack needs to increase to provide the same wind speed. Keeping an even velocity profile is probably important in order to minimize losses due to turbulence. There is probably a lot to be done with the wing-tips that is not done due to aesthetic reasons.

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Active 6 years, 6 months ago. Viewed 4k times. Abhimanyu Pallavi Sudhir 5, 4 4 gold badges 28 28 silver badges 46 46 bronze badges. Active Oldest Votes. A combination of Computational Fluid Dynamics modelling how the air flows over the blade and Finite Element Modelling how the stresses in the metal behave Both of these are complex areas - and when they come to together you need a lot of expensive computers and some even more expensive engineers.

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