RE: KKK turbos,VATN....

["Titus, Brian (NJAOST)" <BTitus@njaost.ml.com>]

Gas turbines (and compressors) have a 'design point' that consists of some
assumed combination of intake angles/swirl angles, mass flow, velocity,
temperature, etc. The blades and vanes are then shaped to be aerodynamically
optimized for the design point. Variable vanes allow the turbine or
compressor to operate more efficiently at off-design points. In jet engines,
variable vanes are used in the compressor section because the compressor is
much more sensitive to off-design conditions, and stalling compressors
create big problems. I don't know if variable vanes are in use in any
turbine sections today -- the environment for jet engine gas turbines is
extremely harsh and the combination of added mechanical complexity and the
need to cool everything in the hot gas path probably still precludes their
use.

As for what a vane does -- in an axial-flow turbine, it is basically a
nozzle that directs incoming air onto the spinning blade so as to get the
most work out of the blade. I can't remember the details anymore, but (I
think) the Euler equation (somehow) tells us that the work done is
proportional to the angle change of the air (incoming to outgoing) through
the blade stage. Wish I could remember more, in a prior life (geez it was a
long time ago) I was an engineer working for a jet engine manufacturer....

Brian

> -----Original Message-----
> From:	Christopher Hanlon [SMTP:cwhanlon@eai.com]
> Sent:	Saturday, March 21, 1998 12:45 PM
> To:	audistuff@juno.com; gerard@poboxes.com
> Cc:	cwhanlon@gate-goliath.eai.com; quattro@coimbra.ans.net
> Subject:	Re: KKK turbos,VATN....
> 
> On Mar 21,  7:54am, Paul R Anderson wrote:
> 
> Since no one seems to actually know, I'll jump in again.
> 
> > Subject: Re: KKK turbos,VATN....
> > I thnk you're getting closer.  The only way that variable vanes on the
> > intake could do anything (as I see it) would be to block flow to the
> > impeller.
> 
> I'd think this would be detrimental to the power of the car.  I guess we
> are on
> the right track though.  I can see the vanes become normal to the passage
> of
> air, thus pulling less air into the motor, and the impellor would have
> less
> resistance, and the vanes rotate so they coincide with the passage of air
> so it
> pushes more air into the intake.
> 
> As for less backpressure, I suppose a turbo with less friction would have
> less
> backpressure...from my point of view, backpressure is irrevelant in this
> context though (even though the add mentions it).
> 
> >From the sound of the add, it seems the turbo is used to provide small
> amounts
> of boost.  So maybe the primary exhaust path is to the muffler, and a
> secondary
> one is to the turbo...so when an increase in throttle is detected, the air
> is
> diverted to the turbo.  Which is opposite of how most turbo cars work
> though...
> 
> 
> > Air would go around the impeller and be drawn in by engine vacuum.  When
> > boost was called for, the vanes would rotate and require the air to be
> > drawn
> > into the impeller and thus provide boost.  This arrangement would allow
> > the shaft to spin freely and have some momentum so that when boost
> > was called for, the shaft wouldn't have to accelerat to provide it.
> >
> > Any comments?
> >
> >
> 
> -- 
>