Cooling nozzle - convection power

[FEAnalyst]

TL;DR

Is it reasonable to calculate power of convective heat transfer ?

Hi,

when modeling convective cooling in FEA one needs to define film coefficient $h$ and ambient temperature $T_{amb}$. The software calculates convective heat flux using this data and current surface temperature $T_s$: $$q=h(T_{s}-T_{amb})$$ However, modeling of moving cooling nozzle may be problematic in FEA software. Some programs have special features meant for moving heat sources (torch/laser) where the user defines position of the tool at a given time and specifies its power. Would it make sense to use this feature for moving cooling nozzle, i.e. calculate the power of convective heat transfer using the above equation (it should be possible to determine surface temperature at the current nozzle location) and simple relation: $P=q \cdot A$ ?

 

[Chestermiller]

What is a "moving cooling nozzle?"

 

[FEAnalyst]

What is a "moving cooling nozzle?"

I was thinking about manufacturing processes where cooling nozzle follows specified path. It’s not easy to simulate something like that in FEA software because normally convection is applied to whole surface. But cooling nozzle would affect only small parts of the surface, each part at different moment of time.

 

[Chestermiller]

I was thinking about manufacturing processes where cooling nozzle follows specified path. It’s not easy to simulate something like that in FEA software because normally convection is applied to whole surface. But cooling nozzle would affect only small parts of the surface, each part at different moment of time.

I'm unable to picture the geometry. Perhaps a sketch would help.

 

[Lnewqban]

I guess the nozzles would locally and temporarly disrupt any established convection flow if they move quickly on a horizontal plane.
With sufficient time after the nozzle goes by, the convection may reach balance again.
At the same time, the blowing action of the nozzle would temporarily energize the heat transfer along its path.
If the above is true, the evaluation of the whole situation should consider speed of movement and blowed area/total area rate.

 

[FEAnalyst]

I'm unable to picture the geometry. Perhaps a sketch would help.

Here's an example - such moving cooling nozzle can be used in friction stir welding:

https://ars.els-cdn.com/content/image/1-s2.0-S1526612519303081-gr1.jpg

As you can see, the nozzle follows the tool providing water cooling to heated parts of the workpiece.