Jet Flow

pmccourt · August 24, 2016, 10:12

Hi,

I am doing a simulation of jet flow from a converging nozzle. One result that I am getting is that the centerline velocity of the jet increases for a couple of mm after exiting the nozzle as opposed to maintaining the exit velocity as I would have expected.

Would anyone be able to explain this?

Thanks

Marpole · August 24, 2016, 10:24

after exiting, the flow will expand. So it basically like a converging-diverging flow. if it is subsonic during converging and sonic at exit, then it will go supersonic after exiting. However, this can not last long. a normal (barrel) shock wave will form and the velocity drops. It is difficult to model shock wave. so simulation can only give you a rough picture.

August 24, 2016, 10:12	Jet Flow	#1
pmccourt New Member Peter Join Date: Jun 2016 Posts: 10 Rep Power: 9	Hi, I am doing a simulation of jet flow from a converging nozzle. One result that I am getting is that the centerline velocity of the jet increases for a couple of mm after exiting the nozzle as opposed to maintaining the exit velocity as I would have expected. Would anyone be able to explain this? Thanks

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August 24, 2016, 10:24		#2
Marpole Senior Member Charles Join Date: Aug 2016 Location: Vancouver, Canada Posts: 148 Rep Power: 9	after exiting, the flow will expand. So it basically like a converging-diverging flow. if it is subsonic during converging and sonic at exit, then it will go supersonic after exiting. However, this can not last long. a normal (barrel) shock wave will form and the velocity drops. It is difficult to model shock wave. so simulation can only give you a rough picture.