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
The big thing that sets engineered products like EXAIR Intelligent Compressed Air Products apart from other devices is the engineering that goes into their design. Several principles of fluidics are key to those designs:
Bernoulli’s Principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluid’s potential energy. It’s explained further here, along with details on how EXAIR products use it.
The one I wanted to discuss today, though, is the Coanda Effect, what it means for our engineered compressed air products, and what they can do for you:
The Coanda effect is named after Henri Coandă, who was the first to use the phenomenon in a practical application…in his case, aircraft design. He described it as “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.” Put simply, if fluid flows past a solid object, it keeps flowing along that surface (even through curves or bends) and pulls surrounding fluid into its flow. Here’s a demonstration, using an EXAIR Super Air Amplifier and a plastic ball:
What’s interesting here is that the Super Air Amplifier is not only DEMONSTRATING the Coanda effect, it’s also USING it:
Air Amplifiers use the Coanda Effect to generate high flow with low consumption.
EXAIR Standard and Full Flow Air Knives also have Coanda profiles that the primary (compressed air) flow follows, and uses, to entrain “free” air from the surrounding environment:
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.
EXAIR Air Wipes can be thought of as “circular Air Knives” – instead of a Coanda profile along the length of an Air Knife, an Air Wipe’s Coanda profile is on the ring of the Air Wipe, which entrains surrounding air into a 360° ring of converging air flow:
Air Wipe – How it works
So that’s the science incorporated in the design of our products. But what does it mean to the user?
Efficiency. Pulling in a tremendous amount of “free” air from the surrounding environment means minimal consumption of compressed air, while still getting a hard hitting, high velocity air flow.
Sound reduction. This air entrainment also creates a boundary layer in the air flow, resulting in a much quieter air flow than you get from a simple open-end blow off.
EXAIR Corporation is committed to helping you get the most out of your compressed air system, and thanks to Mr. Coandă, that includes reducing your compressed air consumption and noise levels. If you’d like to find out more, give me a call.
Russ Bowman, CCASS
Application Engineer EXAIR Corporation Visit us on the Web Follow me on Twitter Like us on Facebook
The Venturi Effect was discovered by Italian physicist Giovanni Battista Venturi who lived between 1746 and 1822. In practice, there were a number of other physicists who were involved in the Venturi Effect but Giovanni Venturi is generally accepted as the first person to discover and explain the effect. So, what is the Venturi Effect, and how does it affect practical everyday living?
“A Venturi is a system for speeding the flow of the fluid by constricting it in a cone shape tube. In the restriction, the fluid increases its velocity, which reduces its pressure and produces a partial vacuum. As the fluid leaves the constriction, its pressure increases back to the ambient or pipe level.”
Any substance that flows is considered a fluid. This includes such things as water, shampoo, sunscreen, and even honey. Although not necessarily obvious, even gases, such as air, can be classified as fluids. So why would someone at EXAIR be talking about Venturi? Our E-Vacs use the Venturi Effect to create vacuum
For most people the Venturi Effect is difficult to understand because you might expect the pressure to increase when a fluid is pushed through a restricted area. The fact that the increase in velocity is greater than any potential increase in pressure means that there is a net increase in velocity and a net reduction in pressure. The ability to mix-and-match certain fluids and gases via this process is relatively straightforward because the reduced pressure allows other substances to be sucked in through a connecting pipe at a rate of your choice.
EXAIR uses the Venturi Effect and other principles within the development of our engineered products. If you have questions or need a solution please call 800.903.9247 or visit us on www.EXAIR.com and let us help you.
