Pressure values at inlet are higher than given BC

Shamoon Jamshed · August 4, 2017, 10:25

hello all,

I am modeling a channel with gas flow. I have given 0 pressure at mass flow inlet. The mass flow rate is 0.171 kg/s. The operating pressure is 80 bar. When I see the pressure plot in XY Plot, it shows me the absolute pressure of 90 bar. Static pressure is 10 bar. I am not getting any idea, why it is so?

Thank you,

LuckyTran · August 9, 2017, 03:02

A mass flow inlet does not impose a pressure constraint unless it's supersonic.

Shamoon Jamshed · August 9, 2017, 06:23

Yes, the flow is supersonic but why at the end of the simulation when I plot XY , the pressure (absolute ) is 90 bar. Where the excess pressure came from? Gas is H2.

August 4, 2017, 10:25	Pressure values at inlet are higher than given BC	#1
Shamoon Jamshed Senior Member Shamoon Jamshed Join Date: Apr 2009 Location: Karachi Posts: 377 Rep Power: 18	hello all, I am modeling a channel with gas flow. I have given 0 pressure at mass flow inlet. The mass flow rate is 0.171 kg/s. The operating pressure is 80 bar. When I see the pressure plot in XY Plot, it shows me the absolute pressure of 90 bar. Static pressure is 10 bar. I am not getting any idea, why it is so? Thank you,

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August 9, 2017, 03:02		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,675 Rep Power: 66	A mass flow inlet does not impose a pressure constraint unless it's supersonic.

August 9, 2017, 06:23		#3
Shamoon Jamshed Senior Member Shamoon Jamshed Join Date: Apr 2009 Location: Karachi Posts: 377 Rep Power: 18	Yes, the flow is supersonic but why at the end of the simulation when I plot XY , the pressure (absolute ) is 90 bar. Where the excess pressure came from? Gas is H2.