Air entrainment is a term that we bring up quite often here at EXAIR. It’s this concept that allows many of our products to dramatically reduce compressed air consumption. The energy costs associated with producing compressed air make it an expensive utility for manufacturers. Utilizing engineered compressed air products that will entrain ambient air from the environment allow you to reduce the compressed air consumption without sacrificing force or flow.
Products such as the Super Air Knife, Super Air Nozzle, Air Amplifier, and Super Air Wipe all take advantage of “free” air that is entrained into the primary supplied airstream. This air entrainment occurs due to what is known as the Coanda effect. Named after renowned Romanian physicist, Henri Coanda, the Coanda effect is used in the design of airplane wings to produce lift. As air comes across the convex surface on the top, it slows down creating a higher pressure on the underside of the wing. This creates lift and is what allows an airplane to fly.
This is also the same principle which is allowing us to entrain ambient air. As the compressed air is ejected through a small orifice, a low-pressure area is created that draws in additional air. Our products are engineered to maximize this entrained air, creating greater force and flow without additional compressed air. Super Air Amplifiers and Super Air Nozzles are capable of up to a 25:1 air entrainment ratio, with just 1 part being the supplied air and up to 25 times entrained air for free!! The greatest air entrainment is achieved with the Super Air Knife at an incredible ratio of 40:1!
This air entrainment principle allows you to utilize any of these products efficiently for a wide variety of cooling, drying, cleaning, or general blowoff applications. In addition to reducing your compressed air consumption, replacing inefficient devices with engineered products will also dramatically lower your sound level in the plant. Sound level in some applications can even be reduced down to a point that would eliminate the need for hearing protection with the OSHA maximum allowable exposure limits set at 90 dBA for an 8-hour shift.
If you have inefficient blowoff devices in your facility, give us a call. An Application Engineer will be happy to help you select a product that will “quietly” reduce your compressed air consumption!
Henri Coanda was a Romanian aeronautical engineer best known for his work on the fluid dynamic principle with his namesake, the Coanda effect. Before this, Henri patented what he labeled as a jet engine.
Henri’s patent (French patent No. 416,54, dated October 22, 1910) gives more information into how he envisioned the motor working. When air entered the front, it passed through different cavities that caused the air stream to first contract and then expand. In Henri’s opinion this contraction and expansion converted the air’s kinetic energy into potential energy. The air ultimately was channeled to a diffuser where it was discharged.
Henri stated that the efficiency of this engine could be improved by heating the air in the cavities, Henri’s logic was that this would increase the pressure of the air passing through.
What is obviously lacking in the patent (including identical ones taken out in England and the United States) is any mention of injecting fuel, which in a true jet engine would combust with the incoming air. Judging only by Henri’s patent, it was little more than a large ducted fan and it could not have flown. Throughout Henri’s career he changed his story many times on whether this plane actually flew or not.
Not to cast too much shade on Henri’s accomplishments he did discover the Coanda effect. The Coanda effect states that a fluid will adhere to the surface of a curved shape that it is flowing over. One might think that a stream of fluid would continue in a straight line as it flows over a surface, however the opposite is true. A moving stream of fluid will follow the curvature of the surface it is flowing over and not continue in a straight line. This effect is what causes an airplane wing to produce lift, and enhance lift when the ailerons are extended while at lower air speeds such as occurs during takeoff and landing.
EXAIR uses the Coanda effect to offer you highly engineered, intelligent and very efficient compressed air products. Our designs take a small amount of compressed air and actually entrain the surrounding ambient air with the high velocity exiting compressed air stream to amplify the volume of air hitting a surface.
When you are looking for expert advice on safe, quiet and efficient point of use compressed air products give us a call. We would enjoy hearing from you.
There are a number of fascinating facts about jets…both the aircraft engines and the EXAIR Intelligent Compressed Air Products:
Because they don’t require dense air to engage spinning blades (like their propeller driven counterparts,) they can operate at much higher altitudes. (Jet aircraft engines only)
They provide a high thrust, directed airstream, which makes them great for part ejection, chip removal, and part drying. (EXAIR Air Jets only)
With few or no moving parts, they are extremely reliable, durable, and safe. (Both jet aircraft engines and EXAIR Air Jets)
They use the Coanda effect (a principle of fluidics whereby a fluid flow tends to attach itself to a nearby surface, and follow that surface regardless of the flow’s initial direction) to do what they do.
EXAIR Air Jets use this principle to generate a vacuum in their throat, pulling in a large amount of “free” air from the surround environment, making their use of compressed air very, very efficient.
Jet (and propeller driven) aircraft wings employ the Coanda effect to create aerodynamic lift, enabling the plane to fly.
Now, since I’m not a pilot, nor do I particularly like to fly, but I AM a fluid dynamics nerd, the rest of this blog will be about the Air Jets that EXAIR makes.
All of our Air Jet products operate on the same principle…using the Coanda effect (as described above) to generate a high volume air flow while minimizing compressed air consumption:
(1) Compressed air enters and is distributed through an annular ring, and directed towards the discharge via the Coanda effect. (2) This causes entrainment of surrounding air, both through the throat, and at the discharge. (3) The total developed flow has tremendous force and velocity, for a minimal consumption of valuable compressed air.(1) Compressed air enters and is distributed through an annular ring, and directed towards the discharge via the Coanda effect.
(2) This causes entrainment of surrounding air, both through the throat, and at the discharge.
(3) The total developed flow has tremendous force and velocity, for a minimal consumption of valuable compressed air.
Model 6013 High Velocity Air Jet is made of brass for economy and durability. The annular ring gap (see 1, above) is fixed by a 0.015″ thick shim. Performance can be modified by changing to a 0.006″ or 0.009″ thick shim, which come in the Model 6313 Shim Set.
Model 6013SS is a Type 303 Stainless Steel version, for higher temperatures – good to 400°F (204°C) – and superior corrosion resistance.
Model 6019 Adjustable Air Jet is brass construction, and dimensionally identical to the Model 6103. Instead of a shim that sets the annular ring gap, though, it has a threaded plug, with a micrometer-style indicator, to “fine tune” the gap.
Model 6019SS is the Type 303 Stainless Steel version…fine tuning adjustability, good for high heat and/or corrosive elements.
If you’d like to find out more about EXAIR’s quiet, efficient, and safe Air Jets, give me a call.
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Henri Coanda was born in Bucharest, Romania on June 7 1886 in a large family with five brothers and two sisters. His father, Constantin M. Coanda, was a decorated Romanian soldier and following in his footsteps he also enlisted in the military. He finished his military education with high honors, but his keen interest in flying and his desire to achieve this sent him down a much different path.
Coanda attended a technical university in Germany and also attended the Superior Aeronautical School in Paris where he graduated at the top of his class with the highest of honors. In less than a year, he had partnered with Gianni Caproni, another known aviator, to construct what was called the Coanda-1910. This aircraft was displayed in Paris at the Second International Aeronautical Exhibition. But, unlike other planes of this time, Coanda’s aircraft did not have a propeller. The plane had an oddly shaped front with built-in rotary blades arranged in a swirling pattern. It was driven by an internal turbine screw that would suck air in through the turbine while the exhausting gases exited from the rear, driving the plane forward by propulsion.
As impressive as this jet engine was, no one believed that it could fly. It is not believed that it ever did achieve flight, despite some contradictory claims by Coanda himself, but was instead struck by disaster. It is rumored that as Coanda injected more fuel into the engine, he was surrounded by flames, thrown from the craft and was lucky to make it out alive. Coanda is not credited as the inventor of the first jet plane, but it is his technology that sky rocketed future aviation research and provided perspective into how jet engines should be built.
Coanda is most known today for his research into what is now known as the Coanda Effect, or propensity of a fluid to adhere to the walls of a convex surface. It is this principle that creates lift on an airplane wing and is also the driving force behind many of EXAIR’s Intelligent Compressed Air Products. If you’d like to discuss how the Coanda effect is utilized in a Super Air Knife, Super Air Amplifier, or Super Air Nozzle give us a call!
Fluidics is an interesting discipline of physics. Air, in particular, can be made to behave quite peculiarly by flowing it across a solid surface. Consider the EXAIR Standard and Full Flow Air Knives:
If you’ve ever used a leaf blower, or rolled down the car window while traveling at highway speed, you’re familiar with the power of a high velocity air flow. Now consider that the Coanda effect can cause such a drastic redirection of this kind of air flow, and that’s a prime example of just how interesting the science of fluidics can be.
As fascinating as all that is, the entrainment of air that these products employ contributes to another principle of fluidics: the creation of a boundary layer. In addition to the Coanda effect causing the fluid to follow the path of the surface it’s flowing past, the flow is also affected in direct proportion to its velocity, and inversely by its viscosity, in the formation of a boundary layer.
This laminar, lower velocity boundary layer travels with the primary air stream as it discharges from the EXAIR products shown above. In addition to amplifying the total developed flow, it also serves to attenuate the sound level of the higher velocity primary air stream. This makes EXAIR Intelligent Compressed Air Products not only as efficient as possible in regard to their use of compressed air, but as quiet as possible as well.
If you’d like to find out more about how the science behind our products can improve your air consumption, give me a call.
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 the catalog 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 Knives, Air Nozzles, and Air Amplifiers all draw in “free” ambient air amplifying both the force and the volume of airflow.
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.
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. Take a look at this video below that demonstrates the air entrainment of a Super Air Amplifier with dry ice:
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.
When I think of “special” in regard to Air Amplifiers, I’m more inclined to think of the applications they can be used in. I mean, the Air Amplifier itself is about as straight-forward as an engineered compressed air product can be:
Considering the simplicity of the product itself, they can be used for a large variety of “typical” applications:
There are no shortage of “special” applications either. They’re used successfully in Air Operated Conveyance applications (when the stronger vacuum head of a Line Vac isn’t required) and we’ve even got a customer who uses one instead of an E-Vac Vacuum Generator for a “pick & place” operation…they’re picking up small, porous fiber discs (sort of like a coffee filter) one at a time, and the E-Vac wanted to pick up a good part of the whole stack, no matter how low they turned the pressure. And of course, I can’t think of anything more special about Air Amplifiers than this:
With fifteen distinct models to choose from in a range of sizes (3/4″ to 8″,) materials (aluminum or Stainless Steel) and even a High Temperature model that’s rated to 700°F (374°C), we’ve still made a fair number of Custom Air Amplifiers too…thirty-four, to be exact, as of this writing.
I won’t bore you with all the details – I can’t, actually, because some of them are proprietary* – but here are some “regular” examples of “special” accommodations:
Connections: EXAIR Air Amplifiers have smooth bores on the inlet & outlet plenums that you can hose clamp a hose (or round duct) to if you need to get air flow from, or to, one place or another. Sometimes, though, they’re going in to an existing system, so we’ve made them with flanges (150#RF and Sanitary Tri-Clamp, for example) or threads (NPT or BSPP.) If you want to use something other than a standard hose or duct line, we can help.
Material of construction: Our durable, lightweight aluminum Super & Adjustable Air Amplifiers are just fine an awful lot of the time. Our type 303 Stainless Steel Adjustable Air Amplifiers will hold up to heat and corrosives. We’ve also in PTFE (Teflon™) as well as a range of metal alloys to meet specific corrosion or wear conditions. If your environment calls for a little something extra, we can help.
Assembly: Super Air Amplifiers are fitted with a stock shim that gives you published performance. We’ve got other thicknesses, though, if you need more (or less) flow, though. Adjustable Air Amplifiers are, well, adjustable…you just thread the plug in/out of the body until you get the results you want. Sometimes the user knows what shim they want in a Super Air Amplifier, or what gap their Adjustable Air Amplifier needs to be set to, and we can assemble it accordingly. If you have a ‘tried-and-true’ performance setting and want it met right out of the box, we can help.
Assembly, part 2: Good engineering practices call for lubrication on O-rings and threaded connections, and we use high quality, general purpose compounds when assembling our Air Amplifiers. These are detrimental, however, in certain situations (silicone exclusion areas, I’m looking at you.) If certain chemicals or compounds are prohibited by your application, we can help.
*Let’s say you’ve done the “heavy lifting” to call out one (or more) of these special design features. If we make a custom product (and that’s not just Air Amplifiers, by the way) using directions based on your time and labor, we’ll treat that product as proprietary to you, and you alone.
EXAIR has 208 catalog pages worth of Intelligent Compressed Air Products on the shelf…8 of those pages are our Air Amplifiers. If you want to talk about customizing one to meet your needs, give me a call.