Ideal gas pressure curve VS Adiabatic pressure curve
Ideal gas pressure curve VS Adiabatic pressure curve
(OP)
I am working on a personal project that simulates an airgun on Microsoft Excel. I basically measure velocity every eighth of an inch given the original volume of my valve and the inner diameter of my barrel. The problem I have is that I am not sure how to do a Adiabatic Pressure curve. I understand how it works, but I am not sure how to what math to use. I appreciate any assistance you can give me. I have a fairly basic background in physics, but I have never worked with this sort of thing up until now, and it is something that I would like to learn. I am using compressed air in all my calculations. Thanks for the help, and I look forward to your response.





RE: Ideal gas pressure curve VS Adiabatic pressure curve
Unless you are a professional engineer, I prefer not to discuss the application of a thermodynamic process that could cause you or some one else harm. Much more than a basic knowledge of physics is needed to engineer and design what you are describing.
You may feel very qualified and enthusiatic about science and engineering as well as its applications. But to do an application safely and correctly you need the basic training in math and engineering - not just the willingness and enthusiasm. I highly recommend you steer your interest in the direction of thermodynamics through a regular Mechanical or Chemical Engineering degree. That would give you a definite jump on materializing a lot of your inventiveness.
RE: Ideal gas pressure curve VS Adiabatic pressure curve
Note that an adiabatic process is one in which no heat is lost or gained by the fluid undergoing the process. It says nothing about work being done on or by the gas. Any time a gas is expanding against something such as a piston, it is undergoing an polytropic process. Google "polytropic process".
Basically, the equation you want is PV^n = constant. The exponent for air with no heat transfer is the ratio of specific heats (k = 1.4). Note also this is absolute pressure, not gage pressure.
RE: Ideal gas pressure curve VS Adiabatic pressure curve
RE: Ideal gas pressure curve VS Adiabatic pressure curve
I think the thing that helped me most in college was the chance to focus on the engineering courses. I didn't have to take any humanities courses or other non-engineering courses during college as I had already taken those while in the service during the evening. They all transferred. Very few other courses were accepted because the college I went to was very particular about what math and science courses could transfer but very lenient about which humanities courses transferred. End result was I could generally get out of taking Enlish, humanities and other courses and focus on engineering. That helped increase the amount of time I had to study engineering during college which was a terrific help in all sorts of ways. So I'd suggest looking at getting the boring courses out of the way while you're still enlisted. That will give you more time for the fun stuff when you go to college.
Also, this forum is primarily for practicing engineers. You might prefer chatting with other students, such as at PhysicsForums: http://www.physicsforums.com/
It's a good message board for people like yourself that are still in college.
Good luck in the service.
RE: Ideal gas pressure curve VS Adiabatic pressure curve
I think you may be simulating the ballistics equation and I will dig this up from my notes as I know I cannot quote the equation from memory.
During my school days, we did exactly what you are doing and I wrote a code which simulates pressures, temperature of the gas including shock waves and expansion waves.
I will be happy to share this with you - drop me an email (aming@adelphia.net)