Senior Design natural gas and air mixing problem
 

Hi Everybody,

So I am a senior that is designing a burner mixing head for a company for my senior design project. I want to model the existing burner head that this company produces to see how well the natural gas and air are mixing. However all I have is access to SolidWorks Flo simulator to accomplish this mixing problem. The problem I run into is that the Flow simulator will not let you directly mix two different fluid sub domains. So my question is there any alternative methodologies to solve this problem in SolidWorks to realistically show the mixing of the natural gas and air. FYI it is a powered burner so there is a mechanical blower that makes the combustion air turbulent.

In the advance module you can even simulate the combustion process.

http://s3.mentor.com/public_document...ced-module.pdf

If you just want to simulate a "cold" case without the combustion then you can do it with one subdomain and specify at the inlets the massfractions of your fuel and oxidizer component.

Is there anyway I can get a more detailed explanation about how to go about this. I personally have no CFD experience and all I have access to is the student and research version of SolidWorks Flow simulator, I attached a simple schematic of the current design that I want to model. I will simplify it of course for the CFD model, but I am specifically just wanting to look at the mixing of two different gases because that will tell me what the combustion will look like.

Chris is right, in case you have a certain mixture already entering the computational domain, you can specify that at the boundary condition to what concentration the mixture will be.
In your case it seems you have separate inlets for the gasses so if you create a lid for the air inlet and one for the fuel then you can set the concentration of each inlet to 1 for the corresponding gas entering through this lid and 0 for the one that is not present at this inlet.
In order to have the concentration available you have to select the two gasses you want to use in the general settings during the project setup or add it afterwards if you forgot it. In the Initial conditions of the general settings you'll find the concentration settings as well, here the values are used for the overall condition at the beginning of the calculation so it makes sense to set air as 1 and the fuel as 0 to have only air in the whole calculation at the beginning as it would be in reality before you turn on the burner and let the fuel flow in.
Now with the fuel inlet set to 1 for fuel and 0 for air and the air inlet the other way around you have two separate inlets and they will automatically mix.
It is not necessary to specify a fluid subdomain in the software as long as the fluid domains are separated or contain different phases such as liquid and gaseous.

Also Chris mentioned that you can use the Advanced module to consider gas combustion. This however is not available in Solid Works, only in FloEFD. Solid Works only has the Electronics Cooling and the HVAC module. The Advanced and LED Module as well as the new FloEDA Bridge module (to import PCB traces) are not offered for Solid Works Flow Simulation.

I hope this helps,
Boris

I hate that two way distribution........