Volumetric Air Flow Rate
Volumetric Air Flow Rate
(OP)
I am trying to determine the difference in the volumetric air flow rate in two different scenarios:
1. Two 3" ID pipes (2 feet long) each flowing 2 cfm of air join together into one 3" pipe (10 feet long). What is the volumetric air flow rate coming out the 3" pipe.
2. Two 3" ID pipes (2 feetlong), each flowing 2 cfm of air.
Each pipe reduces to 2.25 ID pipe (10 feet long). What is the volumetric air flow rate coming out of each of the 2.25 ID pipe?
thanks
1. Two 3" ID pipes (2 feet long) each flowing 2 cfm of air join together into one 3" pipe (10 feet long). What is the volumetric air flow rate coming out the 3" pipe.
2. Two 3" ID pipes (2 feetlong), each flowing 2 cfm of air.
Each pipe reduces to 2.25 ID pipe (10 feet long). What is the volumetric air flow rate coming out of each of the 2.25 ID pipe?
thanks





RE: Volumetric Air Flow Rate
Primarily: air pressure and source
A more realistic number would be expected pressure drop over the two different scenerios. 2 cfm is not very much air through a 3" line, so I would expect your pressure must be quite low....Also identify how much pressure loss you can accept. The other factor will be linear velocity.
RE: Volumetric Air Flow Rate
BobPE
RE: Volumetric Air Flow Rate
Actually, it is two 1 7/8" (3 feet) to two 3" (5 feet) to two 2.25" (~ 10 feet).
Or
Two 1 7/8" (3 feet) to two 3" (5 feet) to one
3" (~10 feet).
Thanks for your responses.
RE: Volumetric Air Flow Rate
The difference is small and the actual performance will depend much more on how you handle turns and transitions.
ko (www.ecooling.biz)
RE: Volumetric Air Flow Rate
piping which was throwing me trying to calculate the actual volumetric air flow rate in each scenario.
I do not know how to determine the back pressure in each scenario as well.
Thanks again.
RE: Volumetric Air Flow Rate
RE: Volumetric Air Flow Rate
It has been quite a while since I have played with an automotive exhaust system, but as I recall what was critical in the design of the system was the back pressure in the system. Is that what you are trying to do? Back into, a specific back pressure (play on words not intended)?
RE: Volumetric Air Flow Rate
The back pressure mentioned should be just the pressure drop through the system (including abrupt exit at the end). So you are wanting to find pressure drop in a piping configuration.
Auto exhause is pulsed- don't know how that affects anything, but maybe some auto engineers could let us know if that makes any difference. If you have a muffler or catalytic converter, they'll probably be more important than the exhaust pipe.
I have heard that reducing exhaust backpressure by putting headers on a car can cause burnt valves if it isn't retuned. No personal experience there, though.
I remember also reading that there have been headers sold that actually had higher exhaust restriction than stock exhaust manifolds.
I remember on the headers, they would always make them equal length so that backpressure on each cylinder was supposedly the same. Never figured out why that mattered, though. The path isn't the same on stock manifolds.