inlet condition (head and discharge) in turbine

CFDturbomachinery · November 25, 2014, 17:08

hi guys,

In CFX: in my turbine simulation: I want to specify head and discharge( mass flow rate). I can specify pressure outlet and speed is specified initially. If I specify only the massfow rate at the inlet, the head keeps going up when i increase the massflow rate keepinng the speedspeed const or variable. So I want to keep the head or discharge constant , and change the speed to get the power output.
How do you do this?

Thanks much.

ghorrocks · November 25, 2014, 18:21

You can't. Either the head or the flow rate needs to adjust to the operating point. So you specify one and the other varies.

CFDturbomachinery · November 26, 2014, 19:37

Thanks much:
Keeping the discharge constant, when I increase speed, the head keeps going up and hence the power output: which should reduce after some point of speeds; I just want to simulate the cases at constant head and discharge varying speeds-is there any way to do this?

ghorrocks · November 27, 2014, 00:07

Have you read the best practises guide in the CFX documentation? It discusses this exact topic. You can find them under the Modelling Guide/Advice on Flow Modelling/Best Practice Guides.

November 25, 2014, 17:08	inlet condition (head and discharge) in turbine	#1
CFDturbomachinery New Member Sharon Wilcox Join Date: Aug 2014 Location: California, USA Posts: 21 Rep Power: 12	hi guys, In CFX: in my turbine simulation: I want to specify head and discharge( mass flow rate). I can specify pressure outlet and speed is specified initially. If I specify only the massfow rate at the inlet, the head keeps going up when i increase the massflow rate keepinng the speedspeed const or variable. So I want to keep the head or discharge constant , and change the speed to get the power output. How do you do this? Thanks much.

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November 25, 2014, 18:21		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	You can't. Either the head or the flow rate needs to adjust to the operating point. So you specify one and the other varies.

November 26, 2014, 19:37		#3
CFDturbomachinery New Member Sharon Wilcox Join Date: Aug 2014 Location: California, USA Posts: 21 Rep Power: 12	Thanks much: Keeping the discharge constant, when I increase speed, the head keeps going up and hence the power output: which should reduce after some point of speeds; I just want to simulate the cases at constant head and discharge varying speeds-is there any way to do this?

November 27, 2014, 00:07		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Have you read the best practises guide in the CFX documentation? It discusses this exact topic. You can find them under the Modelling Guide/Advice on Flow Modelling/Best Practice Guides.