I would assume the flow transitions from a laminar to a turbulent boundary layer at some given rpm (dependent on several variables) and therefore the heat transfer rate would also change with rpm. I find this a very interesting problem and would like to learn more......

Won't the air flow be insulated by the tubulent boundary layer so the temperature of the air flow will never be the same temperature as the plenum? I understand there will be heat transfer, but at a reduced rate as compared with the heat transfer between the plenum and the boundary layer?

I am very interested in these comments to learn more about the heat transfer rate......I have access to Fluent, which I might be able to use on a limited basis. But I would need help with the problem definition and the boundary conditions........

 

I would assume the flow transitions from a laminar to a turbulent boundary layer at some given rpm
If this were steady state flow that would clearly be the case. But with pulsed flow where the air is oscilating (bouncing back and forth) it gets turbulated really quick. Each of the intake runners is humming as a 1/4 wave resonator or like a Coke bottle with air blown across the top of it. The osscilation scrubs away boundary layers and any insulating action they may offer. That is why heat reduction in the plenum is much more important than in the air tube where the flow is more continuous.

Won't the air flow be insulated by the tubulent boundary layer so the temperature of the air flow will never be the same temperature as the plenum?
No. Turbulation does the opposite. It increases the heat transfer rate by orders of magnitude. Laminar boundary layers do the insulating.

I understand there will be heat transfer, but at a reduced rate as compared with the heat transfer between the plenum and the boundary layer?
With or without Iso Thermal, the boundary layer (or a lack of it) will be the same for either configuration.

I am very interested in these comments to learn more about the heat transfer rate......I have access to Fluent, which I might be able to use on a limited basis. But I would need help with the problem definition and the boundary conditions.......
Fluent can calculate the boundary conditions for you, but modeling the plenum and intake runners into Fluent would be a real programming challenge.

 

Its been a while since I looked at fluid dynamics, and after doing some investigation, your explanation makes more sense.

Correcto mundo....

ok......

I was thinking of analyzing a much simplier problem to start with......a simple box with 7 holes, one inlet and 6 outlet.......and apply the G boundary conditions.......I was looking for an estimate for the mass flow rate and plenum temperature. I could vary either or both of these parameters. Do you feel this would be a worthwhile endevour?

Thanks Shooter

 

Hi Shooter,

It will probably be a lot easier and more accurate to simply run a test with the Innovate Motorsport box streaming the data. I will put thermocouples into the flow stream to find the answer.

 

it only took me 12 years but I finally bought one of these gaskets yesterday lol.
plus...

This thread (and forum) deserves a thread bump for useful "heritage" items like this.

 

It's a good upgrade. The upper plenum is cool to the touch after a long drive. I find the upper plenum only heat soaks after parking the car after a drive.