I am interestedin reading Diamond’s paper and his calculation method for locomotive power. Does anyone know if it has been scanned?
Scanned and available (for a fee) from the IMechE collection:
http://pme.sagepub.com/content/156/1/404.abstract
They have free access via OpenAthens if you attend (or have connections) at a participating institution.
The Engineer, March 7, 1947, page 202
http://www.gracesguide.co.uk/images/8/80/Er19470307.pdf
The Engineer, March 14, 1947, page 216
http://www.gracesguide.co.uk/images/1/1e/Er19470314.pdf
I make it p.200 and p.211 respectively (at least in the versions I downloaded)
These are the discussions of the paper, and are very valuable (and worth the download time). Thanks!
(Finding the right page might be important because many an idle hour can be spent reading the other things in these issues of the Engineer!)
I guess the actual paper is about 39 pages long. The Engineer magazine published only about 4½ pages of “extract,” and not all at once. It probably took two editions partly because there was a coal shortage in England in 1947, which affected everything. The discussion of Diamond’s paper begins on page 200, March 7 and continues on page 211, March 14. And there is this editorial commentary:
Locomotive Power at Speed
The incessant demand for higher rates of travel with heavy trains, which has been more especially
Amusing to see Tuplin not missing this chance to mention his favorite ‘dead-horse’ topic, lower boiler pressure as a design desideratum…
It would appear that the editorial commentary either didn’t read the discussion, or misunderstood what Mr. Diamond was saying. See the discussion on the 14th (p. 212):
“…[Diamond] hoped it would be clear that he was not attempting to suggest for one moment that his method of calculating horsepower replaced those methods of determining maximum locomotive capacity in which the boiler had to be taken into account. The whole point was that for the most economical working of a locomotive at speed it was necessary to work it with a better expansion ratio than would normally be used to exhaust the boiler; otherwise the locomotive was not correctly designed [italics mine]. … it was more valuable to have some means of determining what the power would be at a partifcular cut-off which had been predetermined as the correct cut-off to work the engine at that speed, rather than to know as a matter of interest what the engine could do if one tried to boost it to the utmost possible extent.”
It might pay here to remember some of the testing of Union Pacific FEF front ends, where it was perfectly possible to develop high horsepower without creating adequate draft to maintain steam supply at that power. One of the great desiderata in British locomotive design was the preservation of ‘automatic action’ over as wide a range of speeds and powers as possible – the idea that steam generation would be kept proportional to developed hp, so that the locomotive would not be popping off excessively, or contrarily be starved for steam, at any point. This, and not things like backpressure reduction or enhanced drafting via Kylchap-like arrangements, is a good demonstration of the art of practical locomotive design…
Excerpt from Production Engineer, July 1961
Dr. E. L. Diamond
It was with deep regret that the Institution learned of the sudden death of Dr. E.L. Diamond on May 22nd at the comparatively early age of 59.
He was educated at King’s College, London and held the degrees of Master of Science and Doctor of Philosophy. In 1922 he joined the Midland Railway as a pupil of Sir Henry Fowler and was later, for a number of years, on the staff of The Institution of Mechanical Engineers. After service with the Inspectorate of Fighting Vehicles during the Second World War, he joined the British Iron & Steel Research Association, where he served as a Principal Scientific Officer. He went to The British Standards Institution in March 1949, as Head of the Mechanical Engineering Section and, following the reorganisation in 1955, he became a Divisional Chief Technical Officer.
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Thanks to all who replied. I was able to download a copy and am in the process of reading. It is a pretty dense read, with a lot of thermodynamics theory to digest. Diamond’s incorporation of steam passage size and valve events into his thinking on limiting factors of steam locomotive power development makes a lot of sense to me. In this respect, steam locomotives have some similarity with internal combustion engines, as both have an ever shrinking window of time as speed increases to fill and exhaust the cylinder. Interesting stuff, and it is interesting to me to read a technical paper written on the subject of a pretty complex system without the benefit of Computational Fluid Dynamics or other analytical software running on high speed computers.
This triggered a memory about Smokey Yunick’s flow bench that he used to port and polish the heads and manifolds for more power. He said he had to pull about 15 inches of mercury for the bench to give the same results he saw on a dyno. Lots of pressure drop there.
- Erik
What is the “dead horse” regarding lower steam pressure?
What the article is saying is that unless you achieve co-measurate expansion, higher steam pressure does not “buy you anything” on thermal efficiency. The necessary degree of expansion may require compounding, meaning it may not pay to run simples beyond certain boiler pressures?
I have obtained a copy and am now interested in running some of Diamond’s calculations on modern U.S.-prototype simple articulateds and 4-8-4’s. One problem: Diamond only gives about 6 sample K values as examples, and several of those are for European 4 cylinder compounds (with and without poppet valves) and the Pennsy T1 (simple, but poppet valve equipped). The only reasonably comparable piston-valved simples in his paper are the Pennsy K2sa Pacific and E6s Atlantic, neither of which would be considered a superpower design. Interestingly, Diamond’s MEP model doesn’t fit the data for a Pennsy K4s Pacific well at all, the K4 apparently having relatively restrictive steam passages in proportion to its cylinder volume. It does seem possible, given a MEP measurement, speed, cutoff, clearance volume percentage, and nominal boiler pressure to calculate a single point estimate of the K value for just about any locomotive. Has anyone done this? I think it would be interesting to use Diamond’s mathematical model to calculate indicated cylinder horsepower curves for various modern steam locomotives to allow comparison.