Pipe Flow Calculations Forum

This is one of the important conclusions for the construction of the leak down tester, if results obtained with different instruments have to be comparable. The length of the obstruction is not very important; at the contrary the diameter, or more general the ratio between both diameters, is very im...

Indeed, when the velocity increases pressure has to go down, this is a direct consequence of Bernoulli (or the conservation of energy), as it is used in the ventury of our old carburettors. If the pressure goes down, internal energy has to be used and temperature decreases. Of course, if the process...

I see. The leak down tester is a pipe of about 150 mm long and a diameter of 10 mm (in relality it is a aluminium blok with a hole in it of 10 mm diameter) with in the center a restriction of 1mm diameter and 6 mm long. The outflow of the 1mm restriction is thus ending in a pipe of 10 mm and not in ...

Indeed, that's it. Why do you use 1.5 for K ? I considert the discharge as a sudden enlargement and used 10000 for K; see below. In this case the speed is 27 m/s instead of 163m/s and the flow is not choked. I am still in doubt if I understood correctly how to determine K. The process is probably no...

I continued experimenting with the calculator and followed the suggestion of admin concerning the gas outflow calculator. I remenber that the model I used for the leak down tester, was a pipe with 10 mm diameter and "a cylindrical restriction with a diameter of 1 mm and a length of 6 mm. Follow...

I am sorry; I confused the isothermal gas pressure drop with the gas outflow. I don’t know how to apply the “gas outflow calculator” to the leak tester. Compressed air is indeed leaking to the atmosphere through the tester and the motor cylinder, but I have no idea what the "K" of the cyli...

Thank you very much for your answer. Below you will find my reports for the air pressure drop and the gas pressure drop. The conclusions I could drew for the cylinder leak down tester are very interesting. I don't know if people on this forum are interested in this. If so, I am willing to write them...

A few weeks ago I bought a cylinder leak down tester. The principle is that the cylinder of the motor is put under pressure (a few bar) and that the flow rate, necessary to maintain the pressure, is measured. To measure the flow rate, a tube with a restriction is put between the air compressor and t...