Air Cannon Air Speed Calculations

[BriggsFz]

I am working on an Air Blast Cannon for work and am having trouble finding the proper formulas to calibrate it. This Cannon needs to have a barrel with about a 4 inch bore. It will only be used to generate high speed air blasts, so it will not have a projectile. Are there any formulas or online calculators I can use to adjust the Air Reservoir pressures and volumes, relative to the the Barrel size, in order to zero in on my target air speed? I have found a few formulas that seem like they should work, but all of them require a projectile mass (which I don't have) and don't provide units, so I am unsure how to proceed. Additionally, these calculations don't have to be super precise, only accurate enough to give a rough idea on the materials I'll need to use. I am hoping you guys can provide formulas (with units preferably), useful website links, or even data from similar projects. I am looking forward to your responses. Thanks!

 

[jrmichler]

This sounds like a class project, yes? Everything you need is in your fluids book. Start with entrance losses. There will be good information under entrance losses, orifices, and flow nozzles. Then study turbulent flow in pipes, especially the part about how to deal with high velocity flows where the pressure drop is greater than about 10% of the absolute pressure. This is a complex problem, so there is no one single formula that tells you everything you need to know. You need to understand the principles, and work from them.

Or you could just buy an air cannon with all of the engineering done: https://www.martin-eng.com/content/product_subcategory/491/air-cannons-products.

Hint: If the goal is to design parts that handle the pressures, just assume that all pressures are either the highest tank pressure or atmospheric pressure. Then add a safety factor for shock loads.

 

[NatSusan]

There are a few different formulas and calculators you can use to calibrate your Air Blast Cannon. One option is to use the Bernoulli's equation, which relates the pressure, velocity, and height of a fluid. In this case, the fluid would be air. You can use this equation to calculate the velocity of the air coming out of the cannon based on the pressure and volume of the air reservoir and the size of the barrel.

Another option is to use the Ideal Gas Law, which relates the pressure, volume, and temperature of a gas. This equation can help you determine the ideal pressure and volume of the air reservoir to achieve your desired air speed.

You can also use online calculators specifically designed for air cannons, such as the "Air Cannon Calculator" on the SpudFiles website. This calculator allows you to input the desired air speed and barrel size, and it will calculate the necessary air pressure and volume.

It's important to note that these calculations may not be 100% accurate, as there are many factors that can affect the air speed, such as friction and air leakage. However, they should give you a good estimate and help guide you in selecting the proper materials for your project.

Overall, it's always a good idea to do some research and consult with others who have experience with similar projects. You can also experiment with different pressure and volume settings to fine-tune the air speed of your cannon. Good luck with your project!