<VV> Custom Fans

[jvhroberts at aol.com]

 From a schematic standpoint, we are flowing through an orifice. A complicated bunch of them in parallel, but that's what we have here. And, when it comes to cooling, turbulence is actually our friend. Laminar flow is a poor flow regime when it comes to heat transfer. Sure, turbulent flow takes a bunch more power than laminar flow at similar flow rates, but we're trying to cool here, and that's what counts. And under all conditions, the flow is turbulent through these engines. It's also always turbulent through radiators and intercoolers, and in fact the fins are designed specifically to make SURE it's turbulent! 

They slow the air flow down in aircraft simply to reduce external drag, and in some cases, overcooling! 400 MPH air represents one hell of a lot of ram pressure, and if they presented all of this to the engine, it may never get warm, and would seriously increase drag. They don't slow it down for cooling purposes, they slow it down to reduce intake area and increase aircraft performance!

 

John Roberts
 

 

-----Original Message-----
From: Mark Durham <62vair at gmail.com>
To: jvhroberts <jvhroberts at aol.com>; RoboMan91324 <RoboMan91324 at aol.com>; virtualvairs <virtualvairs at corvair.org>
Sent: Wed, May 23, 2012 10:09 pm
Subject: RE: <VV> Custom Fans



John, physics rules, and you are correct, but we are not just flowing thru an orifice. We are flowing through and around different less ideally shaped fins and heads which cause turbulence which aggrevates the ability to cool, just like turbulence will stop a wing from flying. Air stops cooling if it is forced and becomes turbulent as it moves through the fins. Plain and simple. each design was different, depending on how the air flowed through the fins. We actually slowed down the airflow in the intercoolers and engine bays to get better cooling in those aircraft applications. I repeat, more pressure on top of the cylinders may not cool better! Mark Durham 

Sent from my Windows Phone


From: jvhroberts at aol.com
Sent: 5/23/2012 16:05
To: RoboMan91324 at aol.com; virtualvairs at corvair.org; 62vair at gmail.com
Subject: Re: <VV> Custom Fans


 
No knee jerk here. Flow through an orifice goes up with the square of the pressure. So, yes, a big jump in air pressure gets you a jump in air flow. It's that simple, and by the square of the pressure. 

Snarkyness aside, this is a fact and it's not in dispute. 

 

John Roberts