Engine Bay Temperature Convection Modelling

luckyrob · October 25, 2015, 06:32

Having made use of the 'Search' function but had no joy I thought I should post a question to maybe get some help.

I am attempting to model a simplified engine bay of a car in order to assess the cooling effect that different cooling inlet and outlet openings will give. I am not so interested in the engine component temperatures as I am the air within the engine bay.

The problem I am having despite following the Graphics Card and Exhaust Manifold tutorials created by CD-Adapco, is that I seem to get either no, or very little heat transfer to the air surrounding the engine.

If I simply set the engine Continua to a temperature then no transfer occurs. If I leave the Continua temp to ambient and set the engine Region-Heat Source Option to Total Heat Source and then assign a Heat Source value in Watts I get some transfer.

The problem with this is I only get transfer very close to the engine/air interfaces and more importantly I have no idea how to give the engine a realistic Heat Source value! Along with this, the temperature of the engine gets hotter with every iteration and never converges.

I'm sure I am doing something very simple incorrectly, so if someone could point me in the direction of some useful information I would be extremely grateful.

ps. Not sure if it will make a difference but I am running a Steady simulation as as I want to see the effect at a certain vehicle speed

me3840 · October 25, 2015, 16:09

If the engine keeps getting hotter then your simulation is not converged and you have to run it longer. How long are you currently running it, and how large is the mesh?

Ensure you have a good prism mesh around the engine and that the interface from solid to fluid has good matching (99.9% or better).

luckyrob · October 25, 2015, 18:55

Thanks for the advice........I'll get onto checking the quality of my mesh (as I am not sure that it is 99.9% matching) and let you know how I get on.

luckyrob · October 29, 2015, 13:52

Thanks for pointing me in the right direction................

My mesh was not aligned very well at the interfaces; this was due to me not using a polyhedral mesher and because I was using a trimmer. Or at least that is what some research suggested the reason for the interfaces not mating properly was.

The simulation has since converged within 600 iterations.

Much appreciated

October 25, 2015, 06:32	Engine Bay Temperature Convection Modelling	#1
luckyrob New Member Rob Join Date: Jul 2014 Posts: 16 Rep Power: 11	Having made use of the 'Search' function but had no joy I thought I should post a question to maybe get some help. I am attempting to model a simplified engine bay of a car in order to assess the cooling effect that different cooling inlet and outlet openings will give. I am not so interested in the engine component temperatures as I am the air within the engine bay. The problem I am having despite following the Graphics Card and Exhaust Manifold tutorials created by CD-Adapco, is that I seem to get either no, or very little heat transfer to the air surrounding the engine. If I simply set the engine Continua to a temperature then no transfer occurs. If I leave the Continua temp to ambient and set the engine Region-Heat Source Option to Total Heat Source and then assign a Heat Source value in Watts I get some transfer. The problem with this is I only get transfer very close to the engine/air interfaces and more importantly I have no idea how to give the engine a realistic Heat Source value! Along with this, the temperature of the engine gets hotter with every iteration and never converges. I'm sure I am doing something very simple incorrectly, so if someone could point me in the direction of some useful information I would be extremely grateful. ps. Not sure if it will make a difference but I am running a Steady simulation as as I want to see the effect at a certain vehicle speed

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October 25, 2015, 16:09		#2
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 24	If the engine keeps getting hotter then your simulation is not converged and you have to run it longer. How long are you currently running it, and how large is the mesh? Ensure you have a good prism mesh around the engine and that the interface from solid to fluid has good matching (99.9% or better).

October 25, 2015, 18:55		#3
luckyrob New Member Rob Join Date: Jul 2014 Posts: 16 Rep Power: 11	Thanks for the advice........I'll get onto checking the quality of my mesh (as I am not sure that it is 99.9% matching) and let you know how I get on.

October 29, 2015, 13:52		#4
luckyrob New Member Rob Join Date: Jul 2014 Posts: 16 Rep Power: 11	Thanks for pointing me in the right direction................ My mesh was not aligned very well at the interfaces; this was due to me not using a polyhedral mesher and because I was using a trimmer. Or at least that is what some research suggested the reason for the interfaces not mating properly was. The simulation has since converged within 600 iterations. Much appreciated