The shroud should be an inlet guide to the fan. That
is, it should direct and, ideally, straighten the flow
into the radiator. Yes, of course there is a penalty
for any gain, and any type of duct will typically
reduce airflow, but the flow-straightening effect of
the shroud will diminish the negative effect (think of
a teardrop shaped speed car where the intent is to
minimize flow disturbances).
Interesting point, "at speed", believe it or not, if
you are at 60 MPH, the velocity of the air at the
radiator face in a modern car is only about 10-15 MPH
due to flow field disturbances, and also local
resistances to exhaust flow ("Cp's"). A clever design
of an exhaust duct from the radiator (which would also
be the inlet guide to the fan)can guide the air
through a less restrictive flow path.
--- Ulix Goettsch <email@example.com> wrote:
> The "inlet shroud" is abviously a shroud between the
> radiator and the fan.
> What should this look like?
> On a car, the fan is only used when the car moves
> slowly or not at all.
> Wouldn't the shoud reduce cooling efficiency at
> higher vehicle speeds?
> __/__,__ ___/__|__
> http://students.washington.edu/~ulix/ '67
> Sprite '74 X1/9