How EXAIR Uses Fluidics To Make Efficient, Quiet, and Safe Compressed Air Products

EXAIR Intelligent Compressed Air Products incorporate several distinct principles of fluidics into our engineered designs. To be clear, these principles aren’t exclusive to making quiet and efficient compressed air products. I personally have used them all for business and pleasure over the years. In the Navy, for example, the air ejectors that pulled vacuum on the main condensers where our turbines dumped their ‘used’ steam were basically great big Venturis – they restricted the diameter through which a fluid (steam, in this case) flowed, gradually increased that diameter, and doing so, changed the velocity so that a low pressure area (or vacuum) developed in the throat:

Graphic representation of the Venturi effect.

EXAIR E-Vac Vacuum Generators use the Venturi effect to draw vacuum of up to 27″Hg. They’re typically used with Vacuum Cups for pick-and-place material handling applications.

Here are a few examples of Mr. Venturi’s discovery, implemented in modern industry.

I first learned about the Bernoulli principle on a grade school field trip to the National Air Force Museum at Wright Patterson Air Force Base, about an hour from where I grew up. See, this Bernoulli guy discovered that when there is an increase in the speed of a fluid, a simultaneous decrease in fluid pressure occurs at the same time. That’s why airplane wings are shaped like they are – flat on the bottom and curved on top…when the air flowing that extra distance over the top speeds up to get to the back of the wing as fast as the air that’s simply flowing underneath the wing does, the decrease in pressure on top causes the wing (and the plane it’s attached to) rise in the air.

Bernoulli’s Equation: this is the math that proves it works.

The Bernoulli principle is incorporated in to the design & operation of EXAIR engineered Air Knives, Air Wipes, Air Amplifiers, and Air Nozzles.

The Coanda effect is the third fluidics principle that’s incorporated into the design & operation of many EXAIR engineered compressed air products. Its namesake, Henri Coanda, was an early 20th Century aeronautical engineer who discovered that if a jet of fluid exiting an orifice flows across a surface, it’ll tend to not only adhere to and follow that surface (even if it curves or bends), but also entrain fluid from the surrounding area.

EXAIR Intelligent Compressed Air Products such as (left to right) the Air Wipe, Super Air Knife, Super Air Nozzle, and Air Amplifier all use the Coanda effect to entrain enormous amounts of air from the surrounding environment.

There are a couple of easy – and interesting – experiments that demonstrate the Coanda effect, both of which I used when I was a Cub Scout leader and our Pack’s Webelos den was earning their Science Activity Pin:

Turn a faucet on and let the running water flow over the convex ‘bottom’ of a spoon. Everything we know about the laws of gravity say that when the water reaches the ‘bottom-most’ point on the spoon’s convex surface, it ought to fall straight down…but it doesn’t:

Another experiment that defies everything we think we know about gravity can be performed with a ball, and a source of air flow. Here’s a short video, showing how the air flow from an Air Amplifier ‘wraps’ around a ball and holds it in that jet of air:

The Webelos den did this with a leaf blower and a playground ball. Unlike a lot of things I’ve done, I DEFINITELY encourage you to try THAT at home.

For forty years now, EXAIR has been putting these principles of fluidics into practice by engineering & manufacturing the most efficient, quietest, and safest compressed air products on the market. If you’d like to find out how we can help you get the most out of our products – and your compressed air system – give me a call.

Russ Bowman, CCASS

Application Engineer
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Bed Coffee and the Coanda Profile

Photo by Stocksnap and licensed by Pixabay

Every weekend my wife craves her “bed coffee”. I do my best to bring her some coffee in bed at least one, if not both weekend days. It makes her happy, and when she’s happy… The only thing I truly despise about this act of kindness is the actual pouring of the coffee. Now, I’m a decently smart guy but pouring this weekend coffee is a mess. Every time I end up with coffee on the counter, and many times on the mug. And when it gets on the mug it’s over, because it goes to the bottom of the mug and if I forget to wipe that off? Well, it gets on the sheets, because she inevitably rests her coffee on the sheets, and somehow this is my fault, and now she’s not happy anymore… (in fairness, she is still happy and just busts my chops about this part). But why does this happen to me?

It is a little refreshing to realize that I am just a victim of this scientific phenomenon called the Coanda profile. When I start to pour the coffee, the stream adheres to the outer wall of the coffee pot. This causes the coffee to run down the pot and onto the counter, where the cups are sitting (getting that mug bottom soaked in coffee). This is partially caused by the Coanda effect, and partially caused by me not being awake enough to outsmart a coffee pot. The simple solution is to simply increase the flow rate, right? This is correct however, this does not eliminate the Coanda Effect. In fact, even if you are smarter than me you will notice, after you pour the coffee, there is liquid on the side of the pot. That liquid may only be in the form of steam but it’s there, just to a lesser degree. The solution to avoid the mess, is to adjust the pot so that the pour angle is such that gravity overpowers the majority of the Coanda effect. Many times, in my case, this adjustment is too late…

The Coanda phenomena closely depends on several factors, the speed of the jet flow (pouring at a steeper angel), the flow rate (pouring more or less volume over time), and the profile of the container. I believe that a mad scientist invented my particular coffee pot with full intention of messing up countertops all over the world. In fact, he may be a super villain.

At EXAIR, we utilize the Coanda Profile to our benefit on most products. Here are 2 products that are perfect examples of how we use the Coanda Profile to maximize the performance of our products.

Air Amplifiers use the Coanda Effect to generate high flow with low consumption.
Compressed air flows through the inlet (1) to the Full Flow (left) or Standard (right) Air Knife, into the internal plenum. It then discharges through a thin gap (2), adhering to the Coanda profile (3) which directs it down the face of the Air Knife. The precision engineered & finished surfaces optimize entrainment of air (4) from the surrounding environment.

As you can see above, using the Coanda Profile correctly, dramatically increases the efficiency and the entrainment of air in our products. Between the Coanda effect, and the air entrainment, some of our products like the Super Air Amplifiers can output up to 25 times the amount of air that they consume.

Please contact us at anytime to see how the intelligent compressed air products of EXAIR can assist you in your application. And, don’t forget about bed coffee, it’s a win win for you and your spouse…

Thank you for stopping by,

Brian Wages

Application Engineer

EXAIR Corporation
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Cover Photo by monileoni and licensed by Pixabay

Villain image by chrismaguirang and licensed by Pixabay

Coanda Profiles: Who, What and How

Henri Coanda was a Romanian aeronautical engineer most known for his work developing what is today known as the Coanda effect. The Coanda effect is the propensity of a fluid to adhere to the walls of a curved surface. A moving stream of fluid will follow the curvature of the surface rather than continuing to travel in a straight line.  This effect is used in the design of an airplane wing to produce lift. The top of the wing is curved whereas the bottom of the wing remains straight. As the air comes across the wing, it adheres to the curved surface, causing it to slow down and create a higher pressure on the underside of the wing. This  is referred to as lift and is what allows an airplane to fly.

The Coanda effect is also the driving force behind many of EXAIR’s Intelligent Compressed Air Products. Throughout our catalog and website you’ll see us talking about air amplification ratios. EXAIR products are designed to take advantage of this phenomenon and entrain ambient air into the primary air stream. Compressed air is ejected through the small orifices creating air motion in their surroundings. Using just a small amount of compressed air as the power source, Super Air KnivesAir Nozzles, and Air Amplifiers all draw in “free” ambient air amplifying both the force and the volume of airflow.

EXAIR Intelligent Compressed Air Products such as (left to right) the Air Wipe, Super Air Knife, Super Air Nozzle, and Air Amplifier are engineered to entrain enormous amounts of air from the surrounding environment.

Super Air Knives provide the greatest amount of air amplification at a rate of 40:1, one part being the compressed air supply and 40 parts ambient air from the environment. The design of the Super Air Knife allows air to be entrained at the top and bottom of the knife, maximizing the overall volume of air. Super Air Nozzles and Super Air Amplifiers also use this effect to provide air amplification ratios of up to 25:1, depending on the model.

Air Amplifiers use the Coanda Effect to generate high flow with low consumption.

The patented shim design of the Super Air Amplifier allows it to pull in dramatic amounts of free surrounding air while keeping sound levels as low as 69 dBA at 80 psig! The compressed air adheres to the Coanda profile of the plug and is directed at a high velocity through a ring-shaped nozzle. It adheres to the inside of the plug and is directed towards the outlet, inducing a high volume of surrounding air into the primary air stream.

Utilizing the Coanda effect allows for massive compressed air savings. If you would like to discuss further how this effect is applied to our Super Air Knives, Air Amplifiers, and Air Nozzles give us a call. We’d be happy to help you replace an inefficient solution with an Engineered Intelligent Compressed Air Product.

Jordan Shouse
Application Engineer

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Video Blog: Venturi and Coanda Effects

In this video, I will be demonstrating the Bernoulli’s equation and how low pressure can be generated with either the Venturi effect or the Coanda effect. EXAIR uses this principle to make our products very efficient and very effective.

If you have any questions about how EXAIR uses Bernoulli’s phenomenon to create the most efficient products in the compressed air industry, you can contact an Application Engineer. We will be happy to help you.

John Ball
Application Engineer
Twitter: @EXAIR_jb