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

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
Email: johnball@exair.com
Twitter: @EXAIR_jb

Henri Coanda: June 7, 1886 – November 25, 1972

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.

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.    

Super Air Amplifier – flow region

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. 

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

1note – Wikipedia – Coanda effect

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