Over the years of working at EXAIR, I have spoken to thousands of customers. The applications we discuss can run the full range that is showcased in the Solutions section of our website. It is always fun to approach applications when we have to think outside of the box for a solution. Throughout the Application Engineering department, our level of experience here combined with the customer’s knowledge of their setup, sometimes results in a solution that is not straightforward. Sometimes, we have to think outside of the box.
What kind of application may we have encountered where the obvious solution wasn’t the one that worked? One of the best applications that came to mind for me is when a customer was attempting to lift/pick up a very porous piece of filter media like the pre-filter from a Heavy Duty HEPA Vac. This material is extremely lightweight and porous. When hearing from a customer, I want to pick this material up, my mind quickly goes to the E-Vac Vacuum generators which are used to generate vacuum to operate suction cups.
With this material however, the vacuum flow needed is quite extensive and there is another product which is going to be a more efficient use of compressed air. That product, the Super Air Amplifier. As you can see in the photo below, a 2″ Super Air Amplifier easily lifts the porous material and because the suction side is a nominal hose size a hose can easily be attached if needed. The image shows a single amplifier lifting a larger sheet from a bench, these could be organized in an array like suction cups to pick materials up.
The moral of the story is to keep an open mind for solutions, while one path will always work other paths may become a more efficient manner. These solutions don’t always fit inside a box nice and neat. The Super Air Amplifier fit this because the amount of air entrained is tremendous and can easily be utilized to pull low vacuum force/high flow applications. This is very similar to fume evacuation which would be a “normal” application for the Super Air Amplifier.
If you want to discuss any point of use compressed air application with us, contact an Application Engineer and let us help you determine the solution your job needs.
How did a past inventor help generate efficient compressed air products for EXAIR? In the early 20th century, Henri Coanda who was a Romanian aeronautical engineer built an experimental Coanda-1910 airplane. There are some debates if the airplane actually flew, but he invented a curved surface for a wing to generate a Coanda effect. The Coanda effect is the “tendency of a fluid jet to stay attached to a convex surface”1. Thus, a moving stream of fluid will follow the curvature of the surface rather than continuing to travel in a straight line. The Wright Brothers who flew the first airplane in the state where EXAIR is located, Ohio, used the Coanda effect to create lift. With a curved profile, the air will adhere to the surface, causing a low pressure which makes the airplane fly.
EXAIR also uses this Coanda profile to make some of our Intelligent Compressed Air Products™. Like an airplane wing, our curved surface will create a low pressure. How does this help? Well, higher pressure will always travel to lower pressure. Instead of lift, we use the low air pressure to entrain ambient air. This ratio of entrained air to compressed air is what we call the amplification ratio. The higher the amplification ratio, the higher the efficiency for a blowing device. Two main compressed air products that EXAIR manufactures use this type of profile; Air Knives and Air Amplifiers. I will cover both below.
The Air Knives that use the Coanda profile blows air along the length of the knife at a 90o angle from the exit. We offer two types; the Standard Air Knife and the Full Flow Air Knife. The Standard Air Knives are made in Aluminum or Stainless Steel with blowing widths up to 48” (1219mm). The inlet ports are at each end; so, the overall length is 1” (25.4mm) longer than the blowing length. The Full Flow Air Knives have a port, or ports, on the backside. Like the name states, the air blows out the entire length of the air knife. The maximum length is 36” (914mm). Both types use the Coanda profile to generate a low pressure as the air exits the gap and “hugs” the curve (reference photo above). This low pressure draws ambient air into the air stream at a 30:1 amplification ratio for both the Standard Air Knife and Full Flow Air Knife. So, for every one part of compressed air, we entrain 30 parts of ambient air. Besides efficiency, it also adds mass to the air stream for a hard-hitting force. With the engineered profile, the airstream is laminar which gives a consistent force across the entire length and makes them quiet. Not only will they save you money by using less compressed air, but they are also OSHA safe.
The Air Amplifiers use the Coanda profile in a circular form to pull in large amounts of free surrounding air. The Coanda effect is able to generate a low pressure in the center to blow air for cooling, cleaning or removing welding smoke and debris efficiently and quietly. The Air Knives above will blow a flat stream of air while the Air Amplifiers will blow a conical air stream. They can reach amplification ratios up to 25:1. The Super Air Amplifiers use a patented shim to increase efficiency. Unlike fans, they blow a laminar air stream for quick cooling. They do not have any moving parts or motors to wear, so they are very quiet. EXAIR manufactures five different sizes from ¾” (19mm) to 8” (203mm). The Adjustable Air Amplifiers have a plug that can be adjusted to control the blowing from a breeze to a blast. For cleaning surfaces, this is a nice feature to “dial” in the correct amount of blowing force. We also manufacture five different sizes ranging from ¾” (19mm) to 4” (102mm). Both types can be ducted to remove debris, heat or smoke.
Utilizing the Coanda effect allows for massive compressed air savings. Whether it is a flat or round air stream, EXAIR can do this with high amplification ratios. If you would like to discuss further how our Air Knives or Air Amplifiers can help you in your application, please contact us. An Application Engineer will be happy to help you replace your inefficient blowing devices. History has given us a way to increase efficiency for blowing compressed air. Thank you, Henry Coanda.
The big thing that sets engineered products like EXAIR Intelligent Compressed Air Products apart from other devices is the engineering that goes into their design. Several principles of fluidics are key to those designs:
Bernoulli’s Principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluid’s potential energy. It’s explained further here, along with details on how EXAIR products use it.
The one I wanted to discuss today, though, is the Coanda Effect, what it means for our engineered compressed air products, and what they can do for you:
The Coanda effect is named after Henri Coandă, who was the first to use the phenomenon in a practical application…in his case, aircraft design. He described it as “the tendency of a jet of fluid emerging from an orifice to follow an adjacent flat or curved surface and to entrain fluid from the surroundings so that a region of lower pressure develops.” Put simply, if fluid flows past a solid object, it keeps flowing along that surface (even through curves or bends) and pulls surrounding fluid into its flow. Here’s a demonstration, using an EXAIR Super Air Amplifier and a plastic ball:
What’s interesting here is that the Super Air Amplifier is not only DEMONSTRATING the Coanda effect, it’s also USING it:
EXAIR Standard and Full Flow Air Knives also have Coanda profiles that the primary (compressed air) flow follows, and uses, to entrain “free” air from the surrounding environment:
EXAIR Air Wipes can be thought of as “circular Air Knives” – instead of a Coanda profile along the length of an Air Knife, an Air Wipe’s Coanda profile is on the ring of the Air Wipe, which entrains surrounding air into a 360° ring of converging air flow:
So that’s the science incorporated in the design of our products. But what does it mean to the user?
Efficiency. Pulling in a tremendous amount of “free” air from the surrounding environment means minimal consumption of compressed air, while still getting a hard hitting, high velocity air flow.
EXAIR Corporation is committed to helping you get the most out of your compressed air system, and thanks to Mr. Coandă, that includes reducing your compressed air consumption and noise levels. If you’d like to find out more, give me a call.
Russ Bowman, CCASS
Application Engineer EXAIR Corporation Visit us on the Web Follow me on Twitter Like us on Facebook
Much like the popular song from decades ago that was about “money for nothing”, EXAIR can provide you with “air for free”. What we mean by this is that when you choose to use our Super Air Amplifiers, you will produce a large volume of air while only requiring a small amount of compressed air. This is because Air Amplifiers amplify total output flow up to 25 times by entraining (pulling in) ambient air.
So just how does the EXAIR’s Super Air Amplifier do this? By utilizing our patented design (Patent # 5402938) that incorporates a special shim to maintain the air slots precisely. The compressed air is released toward the center of the Super Air Amplifier which creates a constant, high velocity outlet flow across the entire cross sectional area. This
The amplification occurs by entraining most of the ambient air from the back of the Super Air Amplifier. Another small volume of air is added again as the air exits the Super Air Amplifier further increasing the amplification.
Super Air Amplifiers that have outlet diameter’s of 3/4″ (19mm), 1 1/4″ (32mm), 2” (51mm) and 4” (102mm) are supplied with a .003” (0.08mm) shim which is ideal for most applications, however there is the optional .006” (.15mm) and .009” (.23mm) if more air volume and force is needed. The 8” (203mm) Super Air Amplifier comes standard with a .009” (.23mm) shim and for increased performance we offer an optional .015” (.39mm). The chart below explains how to determine the total output flow and air consumption at different operating pressures for each Super Air Amplifier model.
When you need “air for free” or more accurately stated, to get all you can from every SCFM of compressed air you produce, put the EXAIR Super Air Amplifier to work in your facility!