Intermittent inlet feed based on pressure/time

Aeromidd · July 27, 2017, 20:42

Is it possible to make a mass flow inlet (or any other kind of inlet) something that intermittently opens and shuts off flow based on either local pressure gradients or a timestep?
How might I do that?

I'm trying to see if I can simulate the behaviour of a clapper valve / pulse jet combustion process.

ashokac7 · July 28, 2017, 01:36

Yes. I didn't try it. But we can use Stagnation inlet to define pressure as your inlet condition. If pees sure n region goes above the stagnation inlet then flow should stop. But it may give reverse flow. To avoid reverse flow you can define stagnation inlet pressure as a field function such that it is constant when local pressure is less and it is equal to local pressure when local pressure crosses stagnation boundary condition pressure value. Hope this helps. 😊🤗

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Aeromidd · July 28, 2017, 12:24

Cool, thanks very much! Follow up newbie question... how exactly do I implement that in the field function code? How do I describe pressure at the local region? I can't find anything on the list of functions available that defines local pressure. Or do I have to augment a pressure scalar via the position variable somehow?

Thanks

July 27, 2017, 20:42	Intermittent inlet feed based on pressure/time	#1
Aeromidd New Member Michael Join Date: Jul 2017 Posts: 7 Rep Power: 8	Is it possible to make a mass flow inlet (or any other kind of inlet) something that intermittently opens and shuts off flow based on either local pressure gradients or a timestep? How might I do that? I'm trying to see if I can simulate the behaviour of a clapper valve / pulse jet combustion process.

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July 28, 2017, 01:36		#2
ashokac7 Senior Member Ashok Chaudhari Join Date: Aug 2016 Location: Pune, India Posts: 260 Rep Power: 10	Yes. I didn't try it. But we can use Stagnation inlet to define pressure as your inlet condition. If pees sure n region goes above the stagnation inlet then flow should stop. But it may give reverse flow. To avoid reverse flow you can define stagnation inlet pressure as a field function such that it is constant when local pressure is less and it is equal to local pressure when local pressure crosses stagnation boundary condition pressure value. Hope this helps. 😊🤗 Sent from my Redmi Note 3 using CFD Online Forum mobile app

July 28, 2017, 12:24		#3
Aeromidd New Member Michael Join Date: Jul 2017 Posts: 7 Rep Power: 8	Cool, thanks very much! Follow up newbie question... how exactly do I implement that in the field function code? How do I describe pressure at the local region? I can't find anything on the list of functions available that defines local pressure. Or do I have to augment a pressure scalar via the position variable somehow? Thanks