High velocity error

romulo · May 6, 2013, 11:02

I am trying to study spray charactersitics from a nozzle using phoenics ( similar to gas turbine combustion chamber set-up). Using KE Turbulence model, I am getting velocity in the region of 54000m/s. I know it is incorrect as I am expecting to see something in the region of 10-25 m/s (velocity at exit of nozzle).

Initially i was not getting convergence, but this was resolved by tweaking SARAH. start from ambient is off, and I have given pressure=500 psi and tem=120 deg c as initialisation. still the velocity is high. I am kind-of run out of ideas.

any ideas or suggestions are much appreciated. Thanks.

Nozzle exit dia=0.00044m
Nozzle Inlet dia=0.00762m
mass flow rate at fuel inlet=2.9kg/s
density of fuel=750kg/m3
temp of fuel=120 deg c

Air inlet mass flow rate=10kg/s
temp of air=400 deg C
density of air=0.5 kg/m3

[/IMG]

Savio102 · May 30, 2013, 08:10

Romulo,

the mass flow rate is seems to be a bit to much for the diameters you gave. A GT will have that king of flow rate but not for a single nozzle. i suggest you divide the mass flow rate with the number of nozzles in the combustor becayse the 2.9kg/s is what the combustor feels from multiple nozzle, not a single nozzle. I also suggest that you run each part at a time i.e only one inlet and air, and than proceed from there. All the best.

May 6, 2013, 11:02	High velocity error	#1
romulo New Member romulus Join Date: May 2013 Posts: 1 Rep Power: 0	I am trying to study spray charactersitics from a nozzle using phoenics ( similar to gas turbine combustion chamber set-up). Using KE Turbulence model, I am getting velocity in the region of 54000m/s. I know it is incorrect as I am expecting to see something in the region of 10-25 m/s (velocity at exit of nozzle). Initially i was not getting convergence, but this was resolved by tweaking SARAH. start from ambient is off, and I have given pressure=500 psi and tem=120 deg c as initialisation. still the velocity is high. I am kind-of run out of ideas. any ideas or suggestions are much appreciated. Thanks. Nozzle exit dia=0.00044m Nozzle Inlet dia=0.00762m mass flow rate at fuel inlet=2.9kg/s density of fuel=750kg/m3 temp of fuel=120 deg c Air inlet mass flow rate=10kg/s temp of air=400 deg C density of air=0.5 kg/m3 [/IMG]

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May 30, 2013, 08:10		#2
Savio102 New Member Savio Join Date: Oct 2012 Posts: 1 Rep Power: 0	Romulo, the mass flow rate is seems to be a bit to much for the diameters you gave. A GT will have that king of flow rate but not for a single nozzle. i suggest you divide the mass flow rate with the number of nozzles in the combustor becayse the 2.9kg/s is what the combustor feels from multiple nozzle, not a single nozzle. I also suggest that you run each part at a time i.e only one inlet and air, and than proceed from there. All the best.