Henri Coanda: Founder of The Coanda Effect (1886-1972)

EXAIR uses the Coanda effect in many of our products. Henri Coanda is an important figure in the world of fluid dynamics and aerodynamics.

Henri Coanda was a prominent Romanian Inventor and aerodynamics pioneer is known for the creation of the Coanda-1910 experimental plane as well as discovering the Coanda effect. On June 7, 1886 Henri was born in Bucharest Romania to General Constantin Coanda and Aida Danet. In 1899 Henri’s father who desired him to have a military career had him transfer to a Military High School for additional years of schooling, where he graduated with the rank of Sergeant Major. Continuing his studies, he went on to technical school back in Bucharest for Artillery, Military, and Naval Engineering. In 1904 he was sent to an artillery regiment in Germany where he would enroll in Technische Hochshule. Henri did not give up on studying and in 1907 went to Montefiore Institute in Liege, Belgium, where he met Gianni Caproni.

In 1910 Henri and Gianni began a partnership to construct an experimental aircraft which was later called the Coanda-1910. The Coanda-1910 was unlike any other aircraft of its time as it had no propeller; instead it sported an oddly shaped front end with built-in rotary blades arranged in a swirl pattern. These blades were driven by an internal turbine screw that would suck air in through the turbine while exhausting the gases out of the rear, propelling the plane forward. This initial jet engine was quite impressive for the time, but sadly nobody believed it would ever fly and is believed that it never did achieve flight. Coanda is not credited with the invention of the jet engine, but his technology spurred the future of aviation into the future.

During World War 2 Henri spent his time developing the turbo-propeller drive system from his 1910 Biplane. After World War 2 had ended Henri began furthering his research on the Coanda Effect which would become the basis for several investigations into entrained and augmented flow of fluids. Later on in 1969 Henri would spend the last of his days in Romania serving as Director of the Institute for Scientific and Technical Creation. Coanda died on November 25, 1972 in his home town of Bucharest.

Here at EXAIR we have taken Henri Coanda’s, Coanda Effect and applied it to a number of our products to help amplify total airflow and save on compressed air.  The most notable product lines are our Air Amplifiers, Air Nozzles, and Air Knives – which are some of the most efficient products of their kind. These products can help lower your compressed air demand. 

If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Calculating CFM of Air Needed for Cooling

It’s easy to know that EXAIR’s vortex tubes can be used to cool down parts and other items, but did you know that our air knifes can be used to cool down these same things? It’s the same process that we do every day to cool down hot food by blowing on it. Every molecule and atom can carry a set amount of energy which is denoted by physical property called Specific Heat (Cp); this value is the ration of energy usually in Joules divided by the mass multiplied by the temperature (J/g°C). Knowing this value for one can calculate the amount of air required to cool down the object.

Starting out you should note a few standard values for this rough calculation; these values are the specific heat of Air and the specific heat of the material. Using these values and the basic heat equation we can figure out what the amount of energy is required to cool. The specific heat for dry air at sea level is going to be 1.05 J/g*C which is a good starting point for a rough calculation; as for the specific heat of the material will vary depending on the material used and the composition of the material.

Heat Flow Equation
Using the standard heat equation above add in your variables for the item that needs to be cooled down. In the example I will be using a steel bar that is 25 kg in mass rate and cooling it down from 149 °C to 107 °C. We know that the specific heat of steel is 0.466 J/g°C therefore we have everything needed to calculate out the heat load using air temperature of 22 °C.
Calculating Joules/min
Using the heat rate, we can convert the value into watts of energy by multiplying the value by 0.0167 watts/(J/min) which gives us 16,537.18 watts. Furthermore, we can then convert our watts into Btu/hr which is a standard value used for cooling applications. Watts are converted into Btu/hr by multiplying by 3.41 Btu/hr/watt, giving us 56,391.77 Btu/hr.
Converting Joules to Btu/hr
Once you have Btu/hr you can plug the information into a re-arranged Cooling power formula to get the amount of CFM of air required for cooling.
Calculating CFM
As you can see in order to cool down this steel bar you only need to 343 CFM of air at 72°F. This can be done very easily and efficiently by using one of EXAIR’s Air Amplifiers or Air Knife. Sometimes you don’t need to use a vortex tube to cool down an object; sometimes simply blowing on it is good enough and its pretty simple to calculate out which product would fit your application the best.

If you have any questions about compressed air systems or want more information on any EXAIR’s of our products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Usefulness of a Coanda Profile

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 that 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.

Standard Air Knife

Super Air Amplifier with shims

EXAIR uses this Coanda profile to make some of our Intelligent Compressed Air Products™.   Like the airplane wing, our curved surface will also create a low pressure.  How does this help?  Well, high pressure will always travel to low pressure.  Instead of lift, we use the low air pressure to entrain ambient air.  This ratio 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.

Compressed air flows through the inlet (1) to the Standard 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.

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” (25mm) longer.  The Full Flow Air Knives have the port or ports on the back.  The air blows out the entire length of the air knife.  The maximum length is 36” (914mm).

Both types of air knives 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 this engineered profile, the air stream is laminar which gives a consistent force across the entire length and reduces noise levels.  Not only will they save you money,  but they are also OSHA safe.

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

The Air Amplifiers use the Coanda profile in a circular form to pull in dramatic amounts of free surrounding air.  The Coanda effect is able to generate a low pressure to blow air for cooling, cleaning or removing smoke and debris efficiently and quietly.  The Air Knives above 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 force from a breeze to a blast.  For cleaning surfaces, this is a nice feature to “dial” in to exactly what you need.  We also manufacture five different sizes in aluminum and stainless steel ranging from ¾” (19mm) to 4” (102mm).  Both Air Amplifiers can be attached to ducts to remove debris, heat or smoke from the area.

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 applications, please contact us. An Application Engineer will be happy to help you.  History has shown us a way to increase efficiency when using compressed air.  And you can take advantage of it with the Coanda profile.  Thank you Mr. Henri Coanda.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

 

1note – Wikipedia – Coanda effect

Products Built to Last and Maintenance Free

As an avid outdoors man, I have learned a lot about myself during these days of quarantine and social distancing; mainly I don’t quarantine very well. With all the climbing gyms closed, traveling strongly discouraged, and social distancing in place my  lifestyle has been brought to a grinding halt much like many of us. opening up, which will be good for all of us. 

So, in place I have taken upon myself to learn a new hobby that I can do solo and safely. In the past weeks I have spent learning about mountain biking and all that comes with it. This includes the maintenance required to work on a bike, specifically the front derailleur which controls the front major gear changes (and gets damaged if crashed). Realigning the front derailleur is one of the hardest fixes that one can do on a bike as it has three different adjustments that need to be made at the same time. Thus, I embarked on a week long project of learning how to make the adjustment and man was it frustrating.

Performing tricky maintenance can be one of the most frustrating and stress inducing things when all you really want is for something to work without any hassle. Whether its hours just trying to figure out what the issue is or actually fixing it, let’s be honest, it never goes as planned. The same can be said for maintenance on things such as compressors, cars, and production equipment. Here at EXAIR we strive to eliminate this frustration and hair pulling maintenance and replace it with maintenance free products.

EXAIR’s lines of compressed air products such as our Vortex Tubes, Super Air Amplifiers, and Super Air Knives have no moving parts. No moving parts means no wear down parts and no wear down parts means little to no maintenance. Besides the occasional air filter element change out or something getting lodged inside the product EXAIR’s compressed air products will run almost indefinitely as long as they are supplied with a source of compressed air, typically run through a standard 5 micron filter separator. 

Although you cannot really prevent dirt from collecting in a filter separator (that is, in fact what they are meant to do) you can prevent dirt, dust, and debris from getting into your products by using one of EXAIR’s Filter Separators. Filter Separators remove water condensate, dirt, dust, and debris from your compressed air line before it enters your compressed air product. This prevents the particles from disrupting small air outlets or lodging in the small pathways inside our compressed air products and keeps the product running like new.

All in all, maintenance is not fun to have to deal with and can be costly at times. By using EXAIR’s engineered compressed air products you can eliminate at least one thing to worry about on your list of maintenance that needs to be performed. With a little bit of preventive measures you can keep our products running like new for years and years.

If you have any questions or want more information on any EXAIR’s of our products, give us a call, we have a team of application engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Super Air Amplifiers and Amplification Ratio

Super Air Amplifier Family

In the pneumatic industry, there are two types of Air Amplifiers.  One type will amplify the inlet air pressure to a higher compression.  The other type uses the inlet air pressure to amplify the air volume.  EXAIR manufactures the volume type called the Super Air Amplifiers™.

This change in air volume is called the amplification ratio.  So, what does this mean?  The definition of a ratio is the relation between two amounts showing the number of times one value is contained within the other.  For the Super Air Amplifier, it is the value that shows the amount of ambient air that is contained within the compressed air.  The higher the ratio, the more efficient the blowing device is.  With the EXAIR Super Air Amplifiers, we can reach amplification ratios up to 25 to 1.  This means that 25 parts of ambient “free” air is introduced for every 1 part of compressed air.

Air Amplifiers Are Great For blowing!

Why an EXAIR Super Air Amplifier?  Like a fan, they are designed to move air.  But fans use motors and blades to push the air toward the target.  The fan blades “slap” the air which creates turbulent air flows and loud noises. The Super Air Amplifiers do not use any blades or motors to move the air.  They just use a Coanda profile and a patented shim to create a low pressure to draw in the ambient air.  In physics, it is much easier to pull than it is to push.  The process of pulling air through the Super Air Amplifiers make them a more efficient, uniform, and quiet way to blow air.

Most people think that compressed air is free, but it is most certainly not.  Because of the amount of electricity required, compressed air is considered to be the fourth utility in manufacturing plants.  To save on utility costs, it is important to use compressed air as efficiently as possible.  In reference, the higher the amplification ratio, the more efficient the compressed air product.  Manufacturing plants that use open fittings, copper tubes, and drilled pipes for blowing are not properly using their compressed air system.  These types of products generally only have between a 2:1 to 5:1 amplification ratio.  The Super Air Amplifiers can reach a 25:1 ratio.

EXAIR manufactures and stocks five different sizes ranging from ¾” (19mm) up to 8” (203mm) in diameter.  Some of the benefits that the Super Air Amplifiers have is the inlet and outlet can be ducted for remote positioning.  They are very compact and can fit into tight places.  They do not have any moving parts to wear or need electricity to run.  They only need clean compressed air to operate; so, they are maintenance-free.

Another unique feature of the EXAIR Super Air Amplifier is the patented shim which optimizes the low-pressure to draw in more ambient air.   With extracting welding smoke, increasing cooling capacities, and moving material from point A to point B; the more air that can be moved, the better the performance.  And with the patented shim inside the EXAIR Super Air Amplifiers, it provides that.  As an added bonus, they are OSHA safe and meet the standards for noise level and dead-end pressure.

Super Air Amplifier Patented Shims

To explain things in every day terms; the amplification ratio can be represented by gas mileage.  Like your car, you want to get the most distance from a gallon of gasoline.  Similarly, with your compressed air system, you want to get the most for your pneumatic equipment.  An EXAIR Super Air Amplifier has a 25:1 amplification ratio.; so, in other words, you can get 25 mpg.  If you use drilled pipes, open fittings, copper tubes, etc. for blowing, then you are only getting 2 to 5 mpg.  If you want to get the most “distance” from your compressed air system, you should check the “gas mileage” of your blow-off components.  If you need assistance, an Application Engineer at EXAIR can help you to “tune up” your compressed air system.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

People of Interest: Daniel Bernoulli

Daniel Bernoulli

Whenever there is a discussion about fluid dynamics, Bernoulli’s equation generally comes up. This equation is unique as it relates flow energy with kinetic energy and potential energy. The formula was mainly linked to non-compressible fluids, but under certain conditions, it can be significant for gas flows as well. My colleague, Tyler Daniel, wrote a blog about the life of Daniel Bernoulli (you can read it HERE). I would like to discuss how he developed the Bernoulli’s equation and how EXAIR uses it to maximize efficiency within your compressed air system.

In 1723, at the age of 23, Daniel moved to Venice, Italy to learn medicine. But, in his heart, he was devoted to mathematics. He started to do some experiments with fluid mechanics where he would measure water flow out of a tank. In his trials, he noticed that when the height of the water in the tank was higher, the water would flow out faster. This relationship between pressure as compared to flow and velocity came to be known as Bernoulli’s principle. “In fluid dynamics, Bernoulli’s principle states that an increase in the speed of fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluids potential energy”1. Thus, the beginning of Bernoulli’s equation.

Bernoulli realized that the sum of kinetic energy, potential energy, and flow energy is a constant during steady flow. He wrote the equation like this:

Equation 1:

Bernoulli’s Equation

Not to get too technical, but you can see the relationship between the velocity squared and the pressure from the equation above. Being that this relationship is a constant along the streamline; when the velocity increases; the pressure has to come down. An example of this is an airplane wing. When the air velocity increases over the top of the wing, the pressure becomes less. Thus, lift is created and the airplane flies.

With equations, there may be limitations. For Bernoulli’s equation, we have to keep in mind that it was initially developed for liquids. And in fluid dynamics, gas like air is also considered to be a fluid. So, if compressed air is within these guidelines, we can relate to the Bernoulli’s principle.

  1. Steady Flow: Since the values are measured along a streamline, we have to make sure that the flow is steady. Reynold’s number is a value to decide laminar and turbulent flow. Laminar flows give smooth velocity lines to make measurements.
  2. Negligible viscous effects: As fluid moves through tubes and pipes, the walls will have friction or a resistance to flow. The surface finish has to be smooth enough; so that, the viscous effects is very small.
  3. No Shafts or blades: Things like fan blades, pumps, and turbines will add energy to the fluid. This will cause turbulent flows and disruptions along the velocity streamline. In order to measure energy points for Bernoulli’s equation, it has to be distant from the machine.
  4. Compressible Flows: With non-compressible fluids, the density is constant. With compressed air, the density changes with pressure and temperature. But, as long as the velocity is below Mach 0.3, the density difference is relatively low and can be used.
  5. Heat Transfer: The ideal gas law shows that temperature will affect the gas density. Since the temperature is measured in absolute conditions, a significant temperature change in heat or cold will be needed to affect the density.
  6. Flow along a streamline: Things like rotational flows or vortices as seen inside Vortex Tubes create an issue in finding an area of measurement within a particle stream of fluid.

Super Air Knife has 40:1 Amplification Ratio

Since we know the criteria to apply Bernoulli’s equation with compressed air, let’s look at an EXAIR Super Air Knife. Blowing compressed air to cool, clean, and dry, EXAIR can do it very efficiently as we use the Bernoulli’s principle to entrain the surrounding air. Following the guidelines above, the Super Air Knife has laminar flow, no viscous effects, no blades or shafts, velocities below Mach 0.3, and linear flow streams. Remember from the equation above, as the velocity increases, the pressure has to decrease. Since high-velocity air exits the opening of a Super Air Knife, a low-pressure area will be created at the exit. We engineer the Super Air Knife to maximize this phenomenon to give an amplification ratio of 40:1. So, for every 1 part of compressed air, the Super Air Knife will bring into the air streamline 40 parts of ambient “free” air. This makes the Super Air Knife one of the most efficient blowing devices on the market. What does that mean for you? It will save you much money by using less compressed air in your pneumatic application.

We use this same principle for other products like the Air Amplifiers, Air Nozzles, and Gen4 Static Eliminators. Daniel Bernoulli was able to find a relationship between velocities and pressures, and EXAIR was able to utilize this to create efficient, safe, and effective compressed air products. To find out how you can use this advantage to save compressed air in your processes, you can contact an Application Engineer at EXAIR. We will be happy to help you.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

  1. Wikipedia https://en.wikipedia.org/wiki/Bernoulli%27s_principle

Two Types of Air Amplifier: Pressure vs Volume Amplifiers

In the compressed air world, when we talk about an “air amplifier” it can mean one of two things: either a pressure air amplifier, or a volume air amplifier. How do we differentiate the two and what types of applications does each serve?

A pressure air amplifier works as an air pump to increase the pressure of the supplied air, generating pressures ranging from 30 psi up to as much as 1500 psi in some specialized types of pressure amplifiers. Pressure air amplifiers operate only off of the supplied compressed air and do not require a source of electricity to drive the piston amplifying the pressure. They are available in both single-acting and double-acting varieties with the double-acting being the most efficient.

Pressure-type air amplifiers are used in applications where a specific product or process must have a higher pressure than the compressor system can deliver. This includes applications such as: air clamps, presses, pressure testing, air brakes, and also blow molding. The drawback to these products is that the increase in pressure does result in a reduction in volume of air. A point of use receiver tank and over-sizing of the overall system is generally a good practice to ensure sufficient operation.

salapp

On the other side of the amplifier spectrum lies EXAIR with our volume amplifying amplifiers. EXAIR manufactures two different styles of volume air amplifier: The Super Air Amplifier and Adjustable Air Amplifier. These products utilize Bernoulli’s Principle and the coanda effect to draw in large amounts of ambient air that mixes with the supplied compressed to project a hard hitting force of laminar airflow, much greater than what is supplied.

EXAIR’s Adjustable Air Amplifiers are available in both Stainless Steel and Aluminum from sizes ranging from ¾”-4” on the air outlet. The outlet can be ducted or it can be used as-is. The air gap of the Adjustable Air Amplifier is infinitely adjustable, allowing you to regulate both the air consumption and outlet flow from a “breeze” to a “blast”. In addition to the standard Adjustable Air Amplifiers, we also have a High Temperature Air Amplifier available that is capable of withstanding temperatures as high as 700°F.

aalapp4

aal-vacuum

 

 

 

 

 

 

 

 

 

EXAIR’s Super Air Amplifiers utilize a patented shim design to maintain critical positioning of component parts. This allows a precise amount of compressed air to be released at exact intervals toward the center of the Super Air Amplifier. This creates a constant, high velocity outlet flow across the entire cross-sectional area. Free, ambient air is entrained through the unit, resulting in high amplification ratios. The balanced outlet airflow minimizes wind shear to produce sound levels far lower than other similar air movers.

Volume air amplifiers can be used in a variety of blowoff, conveying, drying, cooling, and venting applications. With a range of different sized Super Air Amplifiers and Adjustable Air Amplifiers, EXAIR has a solution for you if you need to move A LOT of air for a variety of reasons. Reach out to an Application Engineer today if you have an application that you believe could be served with a low-cost, simple solution!

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter:@EXAIR_TD