Fluidics, Boundary Layers, And Engineered Compressed Air Products

Fluidics is an interesting discipline of physics.  Air, in particular, can be made to behave quite peculiarly by flowing it across a solid surface.  Consider the EXAIR Standard and Full Flow Air Knives:

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 serve to optimize the entrainment of air (4) from the surrounding environment.

If you’ve ever used a leaf blower, or rolled down the car window while traveling at highway speed, you’re familiar with the power of a high velocity air flow.  Now consider that the Coanda effect can cause such a drastic redirection of this kind of air flow, and that’s a prime example of just how interesting the science of fluidics can be.

EXAIR Air Amplifiers, Air Wipes, and Super Air Nozzles also employ the Coanda effect to entrain air, and the Super Air Knife employs similar precision engineered surfaces to optimize entrainment, resulting in a 40:1 amplification ratio:

EXAIR Intelligent Compressed Air Products such as (left to right) the Air Wipe, Super Air Knife, Super Air Nozzle, and Air Amplifier are engineered to entrain enormous amounts of air from the surrounding environment.

As fascinating as all that is, the entrainment of air that these products employ contributes to another principle of fluidics: the creation of a boundary layer.  In addition to the Coanda effect causing the fluid to follow the path of the surface it’s flowing past, the flow is also affected in direct proportion to its velocity, and inversely by its viscosity, in the formation of a boundary layer.

High velocity, low viscosity fluids (like air) are prone to develop a more laminar boundary layer, as depicted on the left.

This laminar, lower velocity boundary layer travels with the primary air stream as it discharges from the EXAIR products shown above.  In addition to amplifying the total developed flow, it also serves to attenuate the sound level of the higher velocity primary air stream.  This makes EXAIR Intelligent Compressed Air Products not only as efficient as possible in regard to their use of compressed air, but as quiet as possible as well.

If you’d like to find out more about how the science behind our products can improve your air consumption, give me a call.

Adjustable Spot Cooler Provides Needed Cooling In Sunglass Lens Manufacturing

A little while back, I worked with a large eyeglass manufacturer on a sunglass lens cooling application. In their setup, they were dry cutting film-coated lenses with a router and after the lenses are cut, they are passed through several different rinse cycles and inspected for scratches or other damage. They were seeing a high number of reject parts and determined that the heat being generated by the tooling, was causing the irregularities. In an effort to alleviate the condition, they used a section of open flexible tubing to blow compressed air at the bit, which helped a little, but they were still concerned with the amount of scrap material.

I recommended they use our Model # 3825 Adjustable Spot Cooler System in the process. The Adjustable Spot Cooler incorporates a Vortex Tube to provide a temperature drop from the incoming supply air temperature. Using the temperature control valve, the exhausting air temperature and flow can be adjusted to fit the application. The system includes a flexible hose to focus the cold air to the desired area until re-positioned. The system also features a magnetic base that allows for easy mounting. By incorporating the filter separator included in the system, they can remove any moisture and/or contaminants in the air supply, relieving any concern with contamination or damage to the part.

Model 3825 Adjustable Spot Cooler System

If you have a cooling application you’d like to discuss or for help selecting the best product to fit your need,  give me a call at 800-903-9247.

Justin Nicholl
Application Engineer


sunglasses image courtesy of passer-by via creative common license.


People of Interest: Daniel Bernoulli – 2/8/1700 to 3/17/1782

Daniel Bernoulli was born in Groningen, Netherlands on February 8, 1700  and was part of a large family heritage of famous mathematicians – His father Johann Bernoulli, one of the first founders of calculus, his uncle Jacob Bernoulli and his older brother Nicolous. When he was only 7 years old, Daniel began to take an interest in mathematics but his father convinced him that there was no financial gain to be had in mathematics and recommended he focus his studies in business instead. Reluctant at first, Daniel would take his father’s advice under the one condition, that his father would tutor him in calculus and his theories of kinetic energy.

At 13 years old, Daniel attended Basel University where he studied logic and philosophy completing his bachelor’s degree by the age of 15 and earning his master’s degree just 1 year later. Over the years, Daniel’s relationship with his father was strained as a result of him plagiarizing his father’s findings. Eventually, his father passed without reconciling with Daniel. At 24, Daniel became a Professor of Mathematics  at a University in Venice but resigned from the position just 9 years later in 1733.

His most recognized mathematical contribution, Bernoulli’s principle, came in 1938 while performing energy conservation experiments, and he published the results in his book entitled Hydrodynamica . He discovered that when fluid travels through a wide pipe into a smaller, more narrow pipe, the fluid begins to move  faster. He determined that the volume or amount of fluid moving through the pipe remains unchanged but will conform to the shape of the pipe or container as it flows. He concluded that the higher the pressure, the slower the flow of the liquid and the lower the pressure, the faster the liquid flow.

The same principle can be applied to air. As air moves around an obstruction or object, it follows the profile of the part and begins to speed up.

Take for example our Super Air Nozzles. The compressed air exits the nozzle through a series of jets which induces a low pressure around the profile of the nozzle, drawing in ambient air. This entrainment of air, up to 25 times or more, results in a high outlet flow at minimal compressed air consumption.

Super Air Nozzle air entrainment

Many of the products offered by EXAIR incorporate this science which can lead to a more efficient operation by lowering compressed air demand ultimately reducing operating costs. To see how our products can help you save money while increasing process performance, contact an Application Engineer for assistance.

Justin Nicholl
Application Engineer


Bildnis des Daniel Bernoullius image courtesy of Universitätsbibliothek Leipzig via creative commons license


EXAIR Founder’s Day 2018

Last year we announced that EXAIR will celebrate Founder’s Day each year on February 22nd (or the closest working day) in order to commemorate the birthday of our founder, Roy Sweeney. He founded the company in 1983 and drove EXAIR to become the strong, successful and innovative company that it has over the years. Today would have been his 84th birthday.

As we plan to every year, we choose to make this day a celebration and a day to mark our ongoing commitment to the service of others in keeping with the values that Roy and his wife Jackie felt (and feel) very strongly about. It is up to us to continue that commitment.

Like last year, we have made significant donations to organizations that are making a difference right here in our area:

• Freestore Foodbank (www.freestorefoodbank.com)

• Ronald McDonald House of Greater Cincinnati (www.rmhcincinnati.org)

• Women Helping Women (www.womenhelpingwomen.org)

• Bethany House Services (www.bethanyhouseservices.org)

• Elementz (www.elementz.org)

We committed last year to expand our community involvement in 2018, and we have delivered upon that promise. I am proud to announce that EXAIR has established an Employee Volunteer Program that enables every full-time employee with at least 90 days of service to volunteer with organizations of their choice during the normal work week with full pay by EXAIR.

Through this further commitment, we expect that EXAIR and its employees will impact not just a handful, but dozens of organizations and make a much larger positive impact in the community starting this year.

So as we celebrate today with cake and funny memories, we wish Roy a happy birthday. We miss having him here. We remember what he did for all of us and for countless others. And we pledge to continue his commitment to helping those who need it.

Happy Founder’s Day from everyone at EXAIR!

Bryan Peters
EXAIR Corporation