Learning Forum

[MRMR]

Hi

I'm preparing a singe 2d nozzle model for analysis but there appeared a problem which I cannot solve. In uploaded files there is a single sketch of a nozzle  - my problem is that it is a typical airflow but in my analysis wall temperature is higher than fluid one. When I make a normal 2d sketch, mesh it and start the setup and solution there is no heat exchange between fluid and wall. So I want to create interfaces but when I create in Spaceclaim a normal sketch and transfer it to a solid, then after naming inlet (A), outlet ( and walls (C) in meshing stage I dont know how to choose these heat transfer interfaces. When I choose the walls as an interface and inside surface (D) as an another interface there appears errors. 

Thanks for reading and answers
Marcin

[Rob]

Which solver are you using? 

[MRMR]

Fluent

[MRMR]

And sketching in Spaceclaim

[Keyur Kanade]

Hi,

As ANSYS Employee, we can not download attachments. Can you please insert images. 

Others on the forum can download the attachments and pitch in.

Thanks!

Regards,

Keyur

[MRMR]

 It's just a basic picture:

[MRMR]

And when I'm sketching it I just have this surface. The description is in the first post. The length is for example 300mm, my inlet about 60mm, outlet 30. Inlet temperature is about 700K and the wall is constant temperature about 1000K - write it just to show what is going on here. And during my flow the air temperature should rise and if I i just create all boundary conditions and start my calculations it doesnt change at all. And every toutorial I've seen was about to create additional interfaces. But If i create a wall as an interface, and then hide it I cannot anymore set second interface in inside surface area which is tangential to the wall.

[Rob]

Thanks for posting the image. 

If the inlet is 700K and the wall is set to be warmer the air will heat up. Can you check you've set the wall temperature (default is adiabatic) and that the near wall mesh is well refined.  Depending on the flow velocity it's also possible that the increase in air temperature is too low to see: check the Surface Integrals. 

For information, the interface condition is used for where there disconnected meshes that you want/need to connect in Fluent. Here you only have one zone so they're not needed. 

 

[MRMR]

OK great. Thank you very much for answer. I tried with many different options and it didnt change so I thought that it is a problem. Of course I changed the temperature of the wall. I will try again and check Surface Integrals.

Regards
Marcin

[MRMR]

And one question if we are here. Do you know how can I check the amount of heat which was given from the wall to the air in the exact part of nozzle I choose?

[Rob]

You can get the integral from the whole wall. If you label the walls separately (ie top and bottom) then you can also use an xy plot to get heat flux with position.  

Is this a round nozzle? If so you might want to look into the 2d axi-symmetric option. 

[MRMR]

Right now it's a 2d simulation. Next will be a 3d round one.

[Rob]

OK. The results will be fairly different as the 2d model is effectively a slot.