Paul,
Have you seen any development, theoretical or practical, of the
following:
Aircraft have a unique opportunity for using a compounding
turbine's
shaft energy. The cooling drag for an aircraft engine is about
equal to
the energy recovery from turbo compounding. Both are 10-15% of the
power
output. Connecting an exhausting fan directly to the recovery
turbine's
shaft could push the cooling air from the cowling at free stream
velocity or greater.
When the outlet velocity matches the inlet, cooling drag vanishes.
The simplicity of a lightweight volute or shroud and an exhaust
pipe
could replace the complexity, weight, cost, and potential
problems of a
gear train and its safeguarding mechanisms.
Thanks,
Philip Groelz
That is a real good idea Philip.
Here is something similar.
Paul Lamar ...No rotor no motor.
This is an interesting idea and I have thought about it alot in the
last
few days. What I can't figure out is how to get the blower or
sucker
under the cowl. Too big.
Then I thought well why not use an exhaust ejector AKA
augmenter to
evacuate the cowl and reduce the cooling drag. This too uses
the waste
energy in the exhaust to reduce the cooling drag.
Nothing new here. The high velocity exhaust gases entrains air and
sucks it out of the cowl. This is a direct way of utilizing the
waste energy in the exhaust. Here are a couple of 3Ds. Main problem
is it adds to the frontal area and therefore increase the drag on a
tractor airplane. Probably will work fine on a pusher to reduce
the
drag. At least one pusher rotary is flying with an exhaust
ejector and
Charlie Airseman flew his Subaru powered Variez for a few years
with
one.
Here are some old NACA papers on the subject.
http://naca.larc.nasa.gov/index.cgi?method=simple
1. An experimental investigation of rectangular exhaust-gas
ejectors
applicable for engine cooling Manganiello, Eugene J Bogatsky,
Donald ,
NACA Aircraft Engine Research Laboratory (Cleveland, Ohio., United
States)
NACA Report 818, 19 pp.
2. Preliminary investigation of cooling-air ejector performance at
pressure
ratios from 1 to 10 Ellis, C. W. , Hollister, D. P. , Sargent, A.
F., Jr. ,
Lewis Flight Propulsion Laboratory, Cleveland, Ohio. NACA Research
Memorandum
E51H21, 23 pp. , 1951
3. Preliminary air-flow and thrust calibrations of several conical
cooling-air
ejectors with a primary to secondary temperature ratio of 1.0 I
:diameter
ratios of 1.21 and 1.10 Greathouse, W. K. , Hollister, D. P. ,
Lewis
Flight
Propulsion Laboratory, Cleveland, Ohio. NACA Research Memorandum
E52E21, 26 pp. , 1952
-------------------------------------------------------
Bill James still flies a varieze with ejector/augmenter...
Whole airplane,
http://www.ez.org/feature/F0502-1/F0502-1.htm
<http://www.ez.org/feature/F0502-1/F0502-1.htm>
Under cowl pic with ejector:
http://www.ez.org/feature/F0502-1/F0502-24.jpg
A rather creative builder...
Matt-
On second glance it does not look like it meets the geometry
requirement outlined by NACA of an effective augmenter. Here is a
better one.
Paul Lamar
In what way? The exhaust stack terminates well short of the end of the
ejector.
Matt-
The dia. and length of the tapers needs to be in specific ratios.
see
http://www.rotaryeng.net/how-to-cool12.html
Paul Lamar ...No rotor no motor.
--------------------------------------------------------------
BTW this is a real simple way of measuring the thrust of an ejector.
Any homebuilder could make a rig like this.
Also this is a very compact configuration of an ejector that looks
like it would fit almost anywhere. The question is how well does it work? :)
From NACA Research Memorandum E52E21
Stick this in google and you will get the right web site to down load
the pdf. Here is what google came up with:
http://naca.larc.nasa.gov/digidoc/report/rm/21/
Paul Lamar ...No rotor no motor.
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.
