Pressure Inlet BC Inputs

kdavis1521 · October 29, 2021, 15:48

I'm attempting to do a pressure inlet boundary condition for a supersonic oxygen inlet. The values given for the inlet are 914,468 Pa for stagnation pressure, 2.1 for mach number and 298 K for total temperature.

I was under the impression that stagnation pressure would be entered into "Gauge Total Pressure" and the "Supersonic/Initial Gauge Pressure" could then be calculated as static pressure using the isentropic flow relation, resulting in a value of 100,000 Pa. However, when I enter these values I end up with an initial velocity that is more than double what is expected for this oxygen jet. I am struggling to figure out what I am doing wrong and would greatly appreciate if anyone could provide any help. Thanks.

LoGaL · October 29, 2021, 18:52

is the operating pressure set to zero?

kdavis1521 · October 29, 2021, 19:55

No it was not. This fixed my solution, thank you.

October 29, 2021, 15:48	Pressure Inlet BC Inputs	#1
kdavis1521 New Member Kevin Davis Join Date: Oct 2021 Posts: 2 Rep Power: 0	I'm attempting to do a pressure inlet boundary condition for a supersonic oxygen inlet. The values given for the inlet are 914,468 Pa for stagnation pressure, 2.1 for mach number and 298 K for total temperature. I was under the impression that stagnation pressure would be entered into "Gauge Total Pressure" and the "Supersonic/Initial Gauge Pressure" could then be calculated as static pressure using the isentropic flow relation, resulting in a value of 100,000 Pa. However, when I enter these values I end up with an initial velocity that is more than double what is expected for this oxygen jet. I am struggling to figure out what I am doing wrong and would greatly appreciate if anyone could provide any help. Thanks.

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October 29, 2021, 18:52		#2
LoGaL Senior Member Lorenzo Galieti Join Date: Mar 2018 Posts: 373 Rep Power: 12	is the operating pressure set to zero?

October 29, 2021, 19:55		#3
kdavis1521 New Member Kevin Davis Join Date: Oct 2021 Posts: 2 Rep Power: 0	No it was not. This fixed my solution, thank you.