Forgot in 1st equation - "d" is effective diameter of the flow area. Watch
your units - make sure they all cancel to give you a dimensionless number.
----------
> From: Ron Soave <redlotus@spacey.net>
> To: Mike Gigante <mikeg@vicnet.net.au>; Daniel1312@aol.com
> Cc: spridgets@autox.team.net
> Subject: Re: Wind tunnel access minor math ahead
> Date: Sunday, December 13, 1998 6:39 PM
>
> Last math for 1998, I promise.
>
> 1) Mike's first point - The Reynolds Number is:
>
> Re = {(rho) * (v) * d} / (mu)
>
> where
> rho is density of the air ( = to 2.7 * P/T, with pressure in psia and
temp
> in degrees rankine {deg R = deg F +460})
> v = velocity
> mu = kinematic viscosity of the air (varies slightly with temp)
>
> 2) Mike's 2nd point - "Straightness" = laminar flow, which is typically
> considered to be Reynold's number less than 3,000.
>
> You really want to make sure your tunnel provides a repeatable source
flow
> of air with evenly distributed lines in the flow field (representing a
nice
> even pressure delivery).
>
> ----------
> > From: Mike Gigante <mikeg@vicnet.net.au>
> > To: David Ramsey <dwramsey@worldnet.att.net>; Daniel1312@aol.com
> > Cc: spridgets@autox.team.net
> > Subject: Re: Wind tunnel access
> > Date: Monday, December 14, 1998 12:47 PM
> >
> > If you do decide to use scale models and a home built tunnel,
> > there are a couple of important things to take care of.
> >
> > 1) Reynolds Number (size, density, airspeed, viscosity all combine
> > to make a scale model act the same (aerodynamically) as the full
> > size.
> >
> > 2) "straightness" of the air. Baffles and honeycomb (in-line) are used
to
> > reduce the turbulence and vorticity of the air.
> >
> > If you want to be *really* fancy, you could include a rolling road as
> part
> > of the tunnel.
> >
> > Of course if you just want a faster sprite, why not buy the sebring
coupe
> > replica kit from Brian Archer. It's aerodynamics would be a lot better
> > than stock and it is a purdy little thing.
> >
> > Mike
> >
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