Flow Parameters after Pressure Regulator
Flow Parameters after Pressure Regulator
(OP)
Hello
The situation is this:
I have a constant pressure source Po1, followed by a regulator which drops the pressure down to P2, the regulator screws into a larger diameter pipe, which afte ra long length ends to ambient. My question conerns the parameters of the flow at the beginning of the long pipe. I'm not sure how to go about calculating the mach number, pressure or temperature. Im not sure if this is considered a nozzle and can use the isentropic equations or if I need to use isenthalpic, which i don't understand. Also the pressure difference can be greater and less than the critical pressure ratio for sonic flow depending on the chosen source and regulated pressures. Any help is greatly appreciated. I have used the conservation of mass flow but my temperature changes are extremely large especially for supersonic flow.
The situation is this:
I have a constant pressure source Po1, followed by a regulator which drops the pressure down to P2, the regulator screws into a larger diameter pipe, which afte ra long length ends to ambient. My question conerns the parameters of the flow at the beginning of the long pipe. I'm not sure how to go about calculating the mach number, pressure or temperature. Im not sure if this is considered a nozzle and can use the isentropic equations or if I need to use isenthalpic, which i don't understand. Also the pressure difference can be greater and less than the critical pressure ratio for sonic flow depending on the chosen source and regulated pressures. Any help is greatly appreciated. I have used the conservation of mass flow but my temperature changes are extremely large especially for supersonic flow.





RE: Flow Parameters after Pressure Regulator
The regulator is not maintaining a pressure in the large diameter pipe.
The pressure in the large pipe where the regulator flow enters the pipe is ambient pressure plus the pressure drop of the gas from the regulator entry to the end of the pipe. I would guess it's only slightly above ambient.
If you want to regulate the flowrate of the regulator I suggest you put a restriction orifice downstream of the regulator, set the regulator pressure at, say 12 psi and size the RO for the flow you want to provide purge to the large pipe. I would size for 1 ft/sec at 5 INWC or whatever you think the max pressure of the pipe could be.