total pressure(stagnation pressure) is changing in adiabatic nozzle

sriyaz · December 29, 2014, 05:48

Hi
I am trying to solve a simple nozzle problem in Ansys FLUENT.In adiabatic nozzles Total temperature,total pressure should be constant.My solution total temperature is remains constant.But total pressure is not constant in particular place.Please see the attached image. stag pressure.jpg
1)can anyone clarify the reason why it is not constant?
2)How to get constant total pressure?
Thanks in advance.

Details of the problem is given below.

Geometry:geometry.jpg
Material :co2 constant specific heats, molecular weight=44.01 g/mol
density:ideal gas relation.
Model: Invicid model
Boundry condition: 1)INLET

ressure inlet=6 bar(gauge),Total temperature=427K
2)OUTLET: -6 bar(gauge)
3) operation pressure is 8 bar.

LuckyTran · December 29, 2014, 14:14

Are you using the pressure based solver or density based solver?

edit* nevermind, I see the screenshot that says dbns

sriyaz · December 29, 2014, 22:23

I have used density based solver.

sriyaz · December 29, 2014, 22:24

I have used density based solver

sriyaz · December 31, 2014, 23:34

Quote:

Originally Posted by sriyaz

Hi
I am trying to solve a simple nozzle problem in Ansys FLUENT.In adiabatic nozzles Total temperature,total pressure should be constant.My solution total temperature is remains constant.But total pressure is not constant in particular place.Please see the attached image. Attachment 36241
1)can anyone clarify the reason why it is not constant?
2)How to get constant total pressure?
Thanks in advance.

Details of the problem is given below.

Geometry:Attachment 36240
Material :co2 constant specific heats, molecular weight=44.01 g/mol
density:ideal gas relation.
Model: Invicid model
Boundry condition: 1)INLET

ressure inlet=6 bar(gauge),Total temperature=427K
2)OUTLET: -6 bar(gauge)
3) operation pressure is 8 bar.

Anyone please reply to this quoted thread?? it will be very helpful to me.

amin.z · January 1, 2015, 02:37

hey
does happen any oblique or normal shock in the nozzle?
can you attach mach number and pressure contours!?

sriyaz · January 1, 2015, 23:12

For the same above mentioned problem, I have changed the mesh to more fine.Here I have attached the results (plots,contour)...

1.Total pressure along the axistotal pressure.jpg
2.Mach no along the axis mach no.jpg
3.Pressure along the axis static pressure.jpg
4.Mach no contourmach no cont.jpg
5.Pressure contourpressure cont.jpg

December 29, 2014, 05:48	total pressure(stagnation pressure) is changing in adiabatic nozzle	#1
sriyaz New Member Riyaz Ahamed S Join Date: Jul 2014 Posts: 9 Rep Power: 11	Hi I am trying to solve a simple nozzle problem in Ansys FLUENT.In adiabatic nozzles Total temperature,total pressure should be constant.My solution total temperature is remains constant.But total pressure is not constant in particular place.Please see the attached image. stag pressure.jpg 1)can anyone clarify the reason why it is not constant? 2)How to get constant total pressure? Thanks in advance. Details of the problem is given below. Geometry:geometry.jpg Material :co2 constant specific heats, molecular weight=44.01 g/mol density:ideal gas relation. Model: Invicid model Boundry condition: 1)INLETressure inlet=6 bar(gauge),Total temperature=427K 2)OUTLET: -6 bar(gauge) 3) operation pressure is 8 bar.

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December 29, 2014, 14:14		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,672 Rep Power: 65	Are you using the pressure based solver or density based solver? edit* nevermind, I see the screenshot that says dbns

December 29, 2014, 22:23		#3
sriyaz New Member Riyaz Ahamed S Join Date: Jul 2014 Posts: 9 Rep Power: 11	I have used density based solver.

December 29, 2014, 22:24		#4
sriyaz New Member Riyaz Ahamed S Join Date: Jul 2014 Posts: 9 Rep Power: 11	I have used density based solver

January 1, 2015, 02:37		#6
amin.z Senior Member Amin Join Date: Oct 2013 Location: Germany Posts: 397 Rep Power: 14	hey does happen any oblique or normal shock in the nozzle? can you attach mach number and pressure contours!?

January 1, 2015, 23:12		#7
sriyaz New Member Riyaz Ahamed S Join Date: Jul 2014 Posts: 9 Rep Power: 11	For the same above mentioned problem, I have changed the mesh to more fine.Here I have attached the results (plots,contour)... 1.Total pressure along the axistotal pressure.jpg 2.Mach no along the axis mach no.jpg 3.Pressure along the axis static pressure.jpg 4.Mach no contourmach no cont.jpg 5.Pressure contourpressure cont.jpg