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The
sound, smell, and sight of the exhaust
of a steam locomotive is undoubtedly its
most memorable aspect. Interestingly,
the exhaust system is a crucial part of
the design of a steam locomotive, and
one which dramatically affects its
performance for better or worse. Around
the world, from the late 1800's through
the first half of the 20th century, a
great deal of attention was focused on
the design of the exhaust systems for
steam locomotives. Unfortunately, in
most countries steam locomotive
development ceased about the same time
that research in the fields of
engineering related to gas flow and
nozzles exploded. Since WWII, much
research and development has been
performed in these areas as a result of
the development of jet powered aircraft
and rockets. The scientific
knowledge which could have led to
significant improvements in steam
locomotive exhaust design only came
about just as interest was waning in
steam locomotive development.
In the
late 1940's and after, Ing. L. D. Porta
intensely studied steam locomotive
exhaust design, applying scientific
principals which led to further
improvements. This resulted in his
Lempor (Lemaitre-Porta) and
Kylpor (Kylala-Porta) exhausts
used during his early work in Argentina.
The first
notable paper on steam locomotive
exhaust design published by Porta was
with his contemporary Ing. Claudio S.
Taladriz titled "The Exhaust of
Locomotives", in 1957. This paper is
provided courtesy of Jos Koopmans,
translated into English by Porta's son
D. L. Porta from a manuscript in Phil
Girdlestone's collection.
The
Exhaust of Locomotives
by Ing. Livio Dante Porta and Ing.
Claudio S. Taladriz (NEW 18
January 2014)
Perhaps
the most famous publication on steam
locomotive exhaust system design is Ing.
L. D. Porta's Lempor Theory. It
was first published as a technical paper
in 1974, and describes his Lempor
Ejector exhaust system. The
complete Lempor Theory is available
here:
Theory
of the Lempor Ejector as Applied
to Produce Draught in Steam
Locomotives by
Ing. L. D. Porta
Porta
contacted me personally through this
webpage some years ago and requested
that I publicize this theory as much as
possible and request review and comments
from knowledgeable engineers who might
be able to suggest improvements or
refinements to this theory.
One of the few people who took up this
challenge was Jos Koopmans (PhD) of the
Netherlands who made the study of
locomotive exhaust systems his
engineering doctorial thesis. The
work he did for his thesis led him to
write the book "The Fire Burns Much
Better" which documents steam locomotive
exhaust design from the earliest steam
locomotives through the present
day. Jos developed his own theory
for locomotive exhaust design which has
been used to design replacement exhaust
systems for several steam locomotives,
including this one: http://www.trainweb.org/tusp/last30/rtm56.html.
Excerpts from the book and additional
information are available at:
http://www.thefireburnsmuchbetter.nl/
Also
included is a series of photos of the
Kylpor Exhaust system (later superceded
by the Lempor), developed by Ing. Porta
from the Kylchap exhaust system of
Chapelon. These photos can
be accessed here:
Photos of Kylpor
Exhaust system of 2-10-2's of the
Rio Turbio line in Southern
Argentina
This
section provides an overview of steam
locomotive exhaust system development in
the 20th century, showing some of the
many configurations/designs that have
been tried: Exhaust
System Drawings & Photos
In the
last years of his life, Porta was
working on a further development of the
Lempor exhaust, the Lemprex.
While only limited information has been
made public on this system, it focused
on improving ejector performance within
the limited height available on many
steam locomotives by trying to improve
steam/gas mixing within the "mixing
chamber" portion of the ejector.
It is believed that the exhausts
installed on the Donna Teresa Christina
Railroad in Brazil during Porta's work
there in the early 1990's incorporate
elements of his Lemprex exhaust
system. Information and photos on
these engines, including the exhaust
systems, is available here: http://www.trainweb.org/tusp/sergio/teresa_christina.html
Porta proposed the Lemprex for his
improved UK A1 steam locomotive design
as well.
Interestingly,
Porta's final word on locomotive exhaust
design was not his own Lempor
Theory. On the 5AT Project pages,
David Wardale mentions that the
preliminary design for the exhaust
system for the 5AT was based on a
technical paper on the design of
ejectors (not specific to steam
locomotives) published in 1972, which
Porta had brought to his
attention. This document is "The
Prediction of the Optimum Performance of
Ejectors", written by Professor JAC
Kentfield and R. W. Barnes and published
by the Institute of Mechanical Engineers
in the UK. This paper is available
through the IME at this address
(registration required for
search): https://www.imeche.org/library-archive
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