The Bernoulli Principle

When catapults would hurl stones and projectiles at castles there weren’t thinking of how the stones flew or what could make them fly better, often they went with the “Tim Taylor method” of MORE POWER.  It wasn’t until thousands of years later that mathematicians started to talk about gases and liquids and how they react to different scenarios. Things like how does air react to a stone being launched through it. Johann Bernoulli played a significant role and calculated a lot of this out throughout his life and discovered what is now called the Bernoulli Principle.

Bernoulli discovered that when there is an increase in the speed of a fluid, a simultaneous decrease in fluid pressure occurs at the same time. This is what explains how a plane’s wing shape matters. It also can showcase how a curveball coming into the strike zone can fall out and cause an outlandish “STTTeeerriike Three” from the umpire. It is also sometimes confused with the Coandă effect. While both effects have a tremendous impact on our modern lives, the best way I have learned these effects is through videos such as the one below.

As mentioned within the video, there are numerous effects that can closely relate to the Bernoulli effect, the best example I see is the curveball which when implemented correctly can cause a very upset batter, while the pitcher has the game of his or her career.

If you would like to talk about some scientific discoveries that have you puzzled, or if you want to figure out how we can use one of these effects to help your application, contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

Video Source: Fizzics Organization – 10/8/2014 – retrieved from https://www.youtube.com/watch?v=-c_oCKm5FLU&list=PLLKB_7Zd6leNJmORn6HHcF78o2ucquf0U

When To Ask An Expert

With the Springtime comes many outdoor activities in our house. Sometimes they are new, such as archery which just came about in our house in the last couple of weeks.  The other item that it is time for is our family garden. While we have not started any plants from seed this year, and the opportunity to get to a garden center to purchase plants may not happen, we still want to be prepared.  To do that, we prepared the same plot we have used in years past and laid down some landscaping fabric to try and kill off any unwanted weeds that have already started to sprout up through the dirt.

The next activity was to get the tiller out and perform a tune-up/maintenance on it. Sure enough, first, pull and the cord on the trusty engine lets go. The cord didn’t merely break, it looked like something from the Three Stooges as I almost fell backward from my pulling momentum and very nearly punched myself in the face. I proceeded to disassemble the pull-cord cage and found myself in unfamiliar territory.

Pull-Cord Assembly aka Punch-self-in-face-maker

Had this been another part of the engine, the carburetor, electrical kill switch, engine internals, or even the final drive to the tines, I would have been okay. Oddly enough, I have never had to replace one of these recoilers or the rope that comes on them. When you go to YouTube and search for a topic like this you will find a rather large amount of ways to perform a task like this.

Rather than doing that, I enlisted the help of a close friend who has worked for a lawn care/landscaping company for over a decade. He maintains every piece of equipment the company owns and uses. Needless to say, he has replaced quite a few pull ropes in his time.  When I called, due to social distancing we couldn’t meet in person, he, of course, asked several questions about the tiller and in the end helped me to make sure I had the correct replacement rope.

We then set off to walk through the process and the entire thing took less than 15 minutes.  When it was said and done the pull-start felt better than it had ever since I owned the piece of equipment and after sitting since last year still started on the second pull. Thank God for ethanol-free fuel that is still available at certain locations.

All repaired and ready to till!

The point of this story is, what is received and viewed as a simple task for one can be a monumental task for someone else. While my mechanical aptitude was sufficient, I lacked the training and understanding as to why you would perform this process in a given order. My friend, the expert, did not lack that at this point in time. This process was something that was second nature to him.

This is very similar to point-of-use compressed air applications and the EXAIR team. Our team has experience from a multitude of industries and we all focus on utilizing compressed air efficiently and effectively. If we don’t know the process (which is rare) we are willing to learn and ask questions until we understand enough about your application that we can make an educated recommendation for an optimal EXAIR product. We are all here to help each other and to help our customers achieve their goals, so contact us when you need an expert.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Application Database: Compressed Air Use in the Food & Beverage Industry

EXAIR uses many different methods to connect with our customers.  We have our website, social media, blogs, publications etc. We like to share solutions for some of the most common pneumatic problems in the industry.  EXAIR generated a large collection of application information where EXAIR products have already solved problems and improved processes.  We organized them by Application and by Industry.  In this blog, I will show you how to use the Application database; specifically, for the Food and Beverage Industry.

Compressed Air Systems are considered to be a fourth utility within industries because they use a large amount of energy.  Whether an air compressor uses fuel for portable units or electricity, it is important to use this system as efficiently as possible.  This would apply to the Food and Beverage industry.  EXAIR has a library of different processes in which we already improved these areas safely and efficiently.  If you are in the Food and Beverage industry, it would benefit you to take a peek at the implementations where we already improved, establish OSHA safety, and saved money.

Here is how you can find this library.  First, you will have to sign into EXAIR.  Click here: Log In.  Once you fill in the proper information, you can then retrieve a great amount of resources about EXAIR products that we manufacture.   The Application Database is under the Knowledge Base tab.  (Reference photo below).

At the Application Search Library, we have over one thousand application that we reference.  In the left selection pane, we organized then in alphabetical order under two categories, Applications and Industry.   (Reference photo below).

Scroll down in the selection pane until you come to the sub-category: Industry.  Under this Sub-category, you will find three selections that are related to this blog: Food and Beverage, Food Packaging, and Food Processing.  We have other applications that may relate to your process like; Beverage Bottling and Beverage.  You will find many applications that EXAIR has already helped to improve and it is documented.

Why is this important?  If you are a plant manager or owner, the value of the Application Database can improve your current processes with pre-qualified results.  Within the Food and Beverage industry, simple solutions can be found to address those “nagging” issues that you see every day.  For crisis situations and shutdowns, EXAIR categorized these applications in a way to reference quickly and easily.  And since EXAIR has a high volume of stocked quality items, we can get the parts to you very fast; minimizing downtime.

In today’s market, companies are always looking for ways to cut cost, increase productivity, and improve safety.  EXAIR can offer engineered products to do exactly that.  With the “been there and done that” solutions already described in the Application Database; you can have confidence in finding a way in solving pneumatic issues.  If you do not sign up at www.EXAIR.com and take advantage of these offerings, you will be missing out on a great tool in optimizing your compressed air system.

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

 

 

People of Interest: Daniel Bernoulli

Daniel Bernoulli

Whenever there is a discussion about fluid dynamics, Bernoulli’s equation generally comes up. This equation is unique as it relates flow energy with kinetic energy and potential energy. The formula was mainly linked to non-compressible fluids, but under certain conditions, it can be significant for gas flows as well. My colleague, Tyler Daniel, wrote a blog about the life of Daniel Bernoulli (you can read it HERE). I would like to discuss how he developed the Bernoulli’s equation and how EXAIR uses it to maximize efficiency within your compressed air system.

In 1723, at the age of 23, Daniel moved to Venice, Italy to learn medicine. But, in his heart, he was devoted to mathematics. He started to do some experiments with fluid mechanics where he would measure water flow out of a tank. In his trials, he noticed that when the height of the water in the tank was higher, the water would flow out faster. This relationship between pressure as compared to flow and velocity came to be known as Bernoulli’s principle. “In fluid dynamics, Bernoulli’s principle states that an increase in the speed of fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluids potential energy”1. Thus, the beginning of Bernoulli’s equation.

Bernoulli realized that the sum of kinetic energy, potential energy, and flow energy is a constant during steady flow. He wrote the equation like this:

Equation 1:

Bernoulli’s Equation

Not to get too technical, but you can see the relationship between the velocity squared and the pressure from the equation above. Being that this relationship is a constant along the streamline; when the velocity increases; the pressure has to come down. An example of this is an airplane wing. When the air velocity increases over the top of the wing, the pressure becomes less. Thus, lift is created and the airplane flies.

With equations, there may be limitations. For Bernoulli’s equation, we have to keep in mind that it was initially developed for liquids. And in fluid dynamics, gas like air is also considered to be a fluid. So, if compressed air is within these guidelines, we can relate to the Bernoulli’s principle.

  1. Steady Flow: Since the values are measured along a streamline, we have to make sure that the flow is steady. Reynold’s number is a value to decide laminar and turbulent flow. Laminar flows give smooth velocity lines to make measurements.
  2. Negligible viscous effects: As fluid moves through tubes and pipes, the walls will have friction or a resistance to flow. The surface finish has to be smooth enough; so that, the viscous effects is very small.
  3. No Shafts or blades: Things like fan blades, pumps, and turbines will add energy to the fluid. This will cause turbulent flows and disruptions along the velocity streamline. In order to measure energy points for Bernoulli’s equation, it has to be distant from the machine.
  4. Compressible Flows: With non-compressible fluids, the density is constant. With compressed air, the density changes with pressure and temperature. But, as long as the velocity is below Mach 0.3, the density difference is relatively low and can be used.
  5. Heat Transfer: The ideal gas law shows that temperature will affect the gas density. Since the temperature is measured in absolute conditions, a significant temperature change in heat or cold will be needed to affect the density.
  6. Flow along a streamline: Things like rotational flows or vortices as seen inside Vortex Tubes create an issue in finding an area of measurement within a particle stream of fluid.
Super Air Knife has 40:1 Amplification Ratio

Since we know the criteria to apply Bernoulli’s equation with compressed air, let’s look at an EXAIR Super Air Knife. Blowing compressed air to cool, clean, and dry, EXAIR can do it very efficiently as we use the Bernoulli’s principle to entrain the surrounding air. Following the guidelines above, the Super Air Knife has laminar flow, no viscous effects, no blades or shafts, velocities below Mach 0.3, and linear flow streams. Remember from the equation above, as the velocity increases, the pressure has to decrease. Since high-velocity air exits the opening of a Super Air Knife, a low-pressure area will be created at the exit. We engineer the Super Air Knife to maximize this phenomenon to give an amplification ratio of 40:1. So, for every 1 part of compressed air, the Super Air Knife will bring into the air streamline 40 parts of ambient “free” air. This makes the Super Air Knife one of the most efficient blowing devices on the market. What does that mean for you? It will save you much money by using less compressed air in your pneumatic application.

We use this same principle for other products like the Air Amplifiers, Air Nozzles, and Gen4 Static Eliminators. Daniel Bernoulli was able to find a relationship between velocities and pressures, and EXAIR was able to utilize this to create efficient, safe, and effective compressed air products. To find out how you can use this advantage to save compressed air in your processes, you can contact an Application Engineer at EXAIR. We will be happy to help you.

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

  1. Wikipedia https://en.wikipedia.org/wiki/Bernoulli%27s_principle