Premixed combustion of biogas/air mixture

Kenzhia3310 · April 21, 2020, 05:42

Hi, there
My settings here is 0.35 m/s axial velocity for air-fuel inlet(60% CH4 - 40% CO2) and 0.05 m/s axial velocity for co-flow inlet
I suppose to get a result similar to the diagram below, except the black circle region.
I want to know why I get a flattened surface instead of perfect curve shape on the top of surface.
111.jpg

vinerm · April 21, 2020, 07:04

Do you have enough turbulence or diffusion in that region? If it is a laminar flow, then most likely you don't have a developed profile. Diffusion will make it curved. Without that, it will remain flat.

Kenzhia3310 · April 21, 2020, 08:12

I'm dealing with the laminar flow.
It means I need to ensure the velocity at the outlet region is fully-developed?

vinerm · April 21, 2020, 08:14

No, it does not mean that. All it means is that the profile is as per the inlet condition. If you want to compare it against something, then you need to ensure that the inlet conditions are similar to the case you are comparing against.

April 21, 2020, 07:04	Diffusion	#2
vinerm Senior Member Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 35	Do you have enough turbulence or diffusion in that region? If it is a laminar flow, then most likely you don't have a developed profile. Diffusion will make it curved. Without that, it will remain flat. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

April 21, 2020, 08:14	Flow Profile	#4
vinerm Senior Member Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 35	No, it does not mean that. All it means is that the profile is as per the inlet condition. If you want to compare it against something, then you need to ensure that the inlet conditions are similar to the case you are comparing against. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

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April 21, 2020, 08:12		#3
Kenzhia3310 New Member Koo How Boon Join Date: Mar 2020 Posts: 13 Rep Power: 6	I'm dealing with the laminar flow. It means I need to ensure the velocity at the outlet region is fully-developed?