[Spridgets] Weber DCOE vs OER DCOE

Larry Daniels ladaniels at sbcglobal.net
Sun Sep 27 06:09:06 MDT 2009


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From: "Ron Soave" <soavero at yahoo.com>
Sent: Sunday, September 27, 2009 6:27 AM
To: <spridgets at autox.team.net>
Subject: Re: [Spridgets] Weber DCOE vs OER DCOE

> --- On Sun, 9/27/09, Robert E. Shlafer <pilotrob at webtv.net> wrote:
>> "Reynolds Numbers" apply to liquids
>> as far as I know (which is not that far in these respects)
>> however,
>
> Reynold's number applies to all fluids, air included. Off the top of my 
> head at 6am - It is dimensionless, and is equal to the density times the 
> velocity of the fluid times effective diameter of the fuid passage divided 
> by the kinematic viscosity (rho*V*De/mu). For air, Reynold's number is 
> used to calculate the friction factor, and that's equal to .046/Re^.2 if 
> memory serves. The simplified form of Bernoulli in the case we are talking 
> about is that flow: W=density * Area * velocity. As you can see, there are 
> common terms in each equation, so you can manipulate them to come up with 
> a friction factor, but that factor will only tell you the friction per 
> unit length, hence my "nope". In fact, the throat reduction here makes the 
> air behave somewhere in between a swage and a sudden contraction. In both 
> cases, the friction factor varies non-linearly with the ratio of the 
> upstream and downstream areas. You want to keep it gradual, with a 
> reduction angle of less
> than seven degrees for the inner edge of the boundary layer of flow. Throw 
> in additional effects of non-uniform flow fields due to the contraction 
> and the effect on the vena-contracta in the venturi throat and the 
> homogeneity of the flow and downstream mixture suffer.
>
> Or you could switch back to SUs.
>
> Off to the races,
> Ron
> _______________________________________________

I knew that.

Not. 


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