Henri Coanda and his Effect on Compressed Air

Henri defined the Coanda Effect – the tendency of a jet of fluid emerging from an orifice to follow an adjacent flat or curved surface and to entrain fluid from the surroundings so that a region of lower pressure develops.

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.

Henri-Marie Coanda (1885-1972) discovered the Coanda Effect in1930. He observed that a stream of air (fluid) emerging from a nozzle tends to follow a nearby curved surface, if the curvature of the surface or angle the surface makes with the stream is not too sharp. For example, if a stream of fluid is flowing along a solid surface which is curved slightly from the stream, the fluid will tend to follow the surface.

A number EXAIR products are designed to utilize the Coanda Effect and aid their performance. In some products, the Coanda Effect aids to create an amplification area where additional ambient air is drawn into the total airflow to increase total volume of air upon a target. This creates a more efficient and effective product. Also, since not as much compressed air is required, the noise levels decrease for products like EXAIR’s air knives, air nozzles, air jets and air amplifiers. EXAIR has been successful with positive impact for compressed air energy savings and noise reductions helping us meet or exceed OSHA Standard 29 CFR-1910.95 9(a) Maximum Allowable Noise Exposure.

Please contact EXAIR with regards to our Intelligent Compressed Air Products. We can help you with your next cooling, blow-off, drying or any compressed air needs.

Eric Kuhnash
Application Engineer
Email: erickuhnash@exair.com
Twitter: @EXAIR_EK

1- Spoon Coanda image- https://creativecommons.org/licenses/by-sa/2.5/deed.en

Adjustable Vacuum Levels for Different Materials from These Vacuum Generators

When determining a single vacuum generator that will fit a variety of demands, whether it be varying weights, surface finishes or materials, the Adjustable E-Vacs can make quick work of the task at hand. This minimizes the number of parts needed for a variable product line. It also means each application can be adjustable as well. So why would this be needed?

Let’s look at a custom woodworking shop. They could be lifting slabs of lumber that may be rough cut, maybe they are lifting a smooth epoxy river slab, or even sheet of MDF. Each one of these materials will require some adjustment on the vacuum end. The reason being the surface finish and porosity of each material is considerably different.

MDF, expanded out as Medium Density Fiberboard is a common material for woodworkers to use. This material looks and feels smooth and fairly solid. The trick is, it is actually a porous material. You can hook a vacuum hose to one side of it and hold a piece of notebook paper to the other side because the vacuum flow will be pulling through the MDF. This presents a problem when trying to use vacuum to pick and place the board. You will need a higher vacuum flow in order to compensate for the leakage of air when pulling a vacuum. An epoxy coated slab on the other hand, is generally a smooth surface that is non-porous and will require less vacuum flow.

Adjustable E-Vac: How it works

The greatest benefit to the Adjustable E-Vac is being able to easily adapt to meet the needs for both of these materials with a tool-free adjustment. A great example of this is in the video below.

If you would like to discuss which of the Adjustable E-Vacs is right for your variable application, reach out an Application Engineer today. We can all help you determine which of the 4 Adjustable E-Vacs will best fit your application and even help you understand what kind of adjustments will need to be made.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Benefits of Working with EXAIR

30 Day Guarantee

Consider EXAIR as the source of your problem solving products for the following reasons. Our Application Engineers are waiting for your call, e-mail or live chat. They have over 70 years manufacturing experience between them and have experience with an impressive number of different industries and process problems. Add our customer service staff to that mix and you will experience orders that are shipped the same or next day (orders received by 2pm EXAIR time ship same day), with a fast and accurate order confirmation. EXAIR shipped products on-time 99.8% in 2021, and we continue that into 2022.

Our website and catalog include 16 problem solving product lines and thousands of products, technical data, photos and drawings to help you with your project. When reviewing our website or catalog, chances are you will find the answers to some of your industrial/production problems. Our catalog products are stock items, so in most cases we will process and ship orders the same day! Having the capability to get our products to your facility allows you to begin familiarizing yourself with our product(s) and perform trial(s). Since we manufacture these products locally, in Cincinnati, OH, we have the ability to make custom solutions if any of our stock products do not meet your needs.

EXAIR has competitive prices but you will also see cost savings from the efficiencies you realize with our Intelligent Compressed Air Products. Reducing your SCFM usage will decrease your energy cost. Our products also come with EXAIR’s 5 year Built to Last Warranty!

EXAIR leads the way in standards compliance by making certain our products meet the standards set forth by many organizations. You will see CE, RoHS, REACH, Conflict Mineral Free and OSHA compliance are common for our products. When considering safety, our products meet or exceed OSHA Standards 29 CFR-1910.95 (a) maximum allowable noise exposure and OSHA standard CFR 1910.22 (b) harmful dead end pressure.

Please visit www.EXAIR.com or request a catalog.

Eric Kuhnash
Application Engineer
E-mail: EricKuhnash@EXAIR.com
Twitter: @EXAIR_EK

The Venturi Effect: Discovered by Giovanni Battista Venturi

Giovanni Battista Venturi was born in 1746 to an affluent family in Reggio, Italy. An aspiring student, Giovanni was ordained as a priest and a professor by the age of 23. An avid historian of science at the University of Modena, he was the first to emphasize Leonardo da Vinci as a scientist rather than just an artist as he’s more commonly known. Despite his love for history, it wasn’t long before the University of Modena became aware of his talents in mathematics where they appointed him as professor of geometry and philosophy in 1774. During his tenure at the University of Modena, Giovanni was promoted to the Professor of Experimental Physics, served as the Duke of Modena as the State engineer and auditor, later serving diplomatic roles in both France and Switzerland.

Giovanni is most well-known for his work in developing what is now known as the venturi effect. In 1797, he published a study on the flow of water through short cylindrical tubes. It wasn’t until 1888 that Venturi’s design was applied to something practical when a man named Clemens Herschel received a patent for the first commercial venturi tube. The original purpose of the venturi tube was to measure the amount of water used in individual water mills and is still used to this day as a means of measuring fluid flows.

Venturi tube.jpg
Venturi Tube

The venturi effect is a principle in fluid dynamics and states that a fluid’s velocity must increase as it passes through a constricted pipe. As this occurs, the velocity increases while the static pressure decreases. The pressure drop that accompanies the increase in velocity is fundamental to the laws of physics. This is known as Bernoulli’s principle. Below is an illustration of how the venturi effect works inside of a constricted tube.

venturi

In everyday life, the venturi principle can be found inside of many small engines such as lawn mowers, gas powered scooters, motorcycles and older style automobiles. Inside the carburetor, there is a small tube through which filtered air flows from the intake. Inside of this tube is a short narrowing. When the air is forced to constrict, its velocity increases and creates a vacuum. This vacuum draws in fuel and mixes with the air stream causing it to atomize.  As the throttle valve is opened further, more fuel is forced into the engine. This increases the RPM and creates more power.

inlineworks
In-Line E-Vac

This principle is also applied to EXAIR’s line of E-Vac products to create vacuum. The .gif below illustrates how an In-Line E-vac works. (1) Compressed air flows through the inlet (2) and is directed through a nozzle, constricting the flow of air. (3) As the air stream exhausts, it expands causing a decrease in pressure and an increase in velocity prior to passing through the venturi. (4) A vacuum inlet tangential to the primary airflow is located at the suction point between the orifice and the venturi. (5) The airflow that is drawn through the vacuum inlet mixes with the primary airstream, then exhausts on the opposite end.

The venturi effect is used in a variety of other EXAIR products used for cooling, drying and cleaning, in addition to the vacuum generators. If you have a process in your facility that may benefit from an Intelligent Compressed Air solution, give us a call. We’d be happy to discuss your application and implement a solution to both reduce your compressed air costs and improve worker safety.

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

Photo: Venturi Tube with labels by ComputerGeezer and Geof.  GNU Free Documentation License