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.
1note – Wikipedia – Coanda effect