Re: Wheezin

[dan_masi@MENTORG.COM (Dan Masi)]

On Mar 19,  3:18pm, PDQSHIP@aol.com wrote:
> Subject: Wheezin
> In a message dated 96-03-18 13:19:44 EST, you write:

> >... If you start with a lower ambient 
> >pressure (lower atmospheric pressure), the inlet air is necessarily LESS 
> >DENSE than at higher atmospheric pressures.  Less dense air means less 
> >mass of air (specifically for a given velocity).  Less mass coming out of 
> >the cylinder will result in less mass to push the turbine side (exhaust 
> >side) of the turbo.  Result - the turbo will spin more slowly and 
> >compress less than at higher atmospheric pressures. 

Incomplete analysis!  For instance, you are neglecting the fact that
the turbine's speed is also a function of the resistance presented
by the incoming air at the compressor side.  Lower atmospheric
density presents less resistance to the spinning compressor, so
the turbine will potentially spin *faster*!  Also, there are boundary
condition problems with the analysis.  If there is less mass coming out
of the engine to drive the turbine, then there was less mass that
entered the engine, again meaning that the compressor did less
work...


Dan Masi