Is E.L. Diamond's "The Development of Locomotive Power at Speed" available online?

[sgriggs]

I am interestedin reading Diamond's paper and his calculation method for locomotive power.  Does anyone know if it has been scanned?

[Wizlish]

sgriggs

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.

 

[wanswheel]

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

[Wizlish]

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!)

[wanswheel]

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 manifest in passenger services, has naturally called for greater power output on the part of locomotives. Further, as, of course, any increase in power can only be obtained by a corresponding increase in the mean steam pressure acting in the cylinders, it follows that the design and proportioning of cylinder steam ports, together with adequate valve action to give a proper steam distribution, must both separately and collectively be given close attention. Stated quite shortly, the aim must be to pass the greatest possible weight of steam through the cylinders per unit of time, and it is this latter consideration of the time interval progressively shortened at high speeds that presents the crux of the problem. The ideal would, of course, be the maintenance of a definite mean pressure throughout the entire speed range. For then, power would increase directly with speed. That ideal, however, is far from being reached, though improvement made in cylinder design and in the steam distribution have greatly increased mean pressures at given rates of cut-off, through the higher speed range—a fact brought out in an interesting manner by the paper presented for discussion by E. L. Diamond at a meeting of the Institutionof Mechanical Engineers, London, on February 21st, of which we include an abstract in the present issue.

The author divided his paper, entitled "The Development of Locomotive Power at Speed," into two parts. In the first, the efficiencies of the steam action in the cylinders at different steam pressures and specific steam consumptions per indicated horsepower, corresponding to various rates of admission and for different boiler steam pressures, were estimated. In making these computations, assumed clearance volumes of 5, 10 and 15 per cent were taken into consideration. As a basis for these computations, the author used ideal indicator diagrams, constructed for each different steam pressure, and a constant steam temperature of 600 deg. Fah., while the exhaust pressure was taken as being in all cases 18 lb. per square inch absolute. The second part of the paper was devoted to what is really its main purpose, namely, the determination of the mean effective pressure in cylinders having a definite clearance volume expressed as a percentage of the swept volume at any speed and rate of cut-off. The formula proposed for determining the mean pressure is based on the mean effective pressures shown by the ideal diagrams, corrected by a factor, while the fall in pressure with increasing speeds in revolutions per minute is taken as being proportioned to the square root of the assumed speed. Characteristic curves of mean pressure, estimated according to the author's method, drawn through plotted points from various tests, show fair agreement, from which it is concluded that the formula “is a more accurate guide in estimating power at speed of a projected design than either Cole's constants or the Kiesel formula, with its illogical basis in the boiler, provided appropriate values for the constant are taken.”

Whether or not agreement will be found with that statement seems very problematical. For, if it is conceded that the proposed method for computing mean pressures is valid, the actual cylinder power available will always be determined by the steaming capacity of the boiler, as, until that capacity is established, it is impossible to know at what speed a given cut-off can be maintained. The estimation of the mean effective pressure in locomotive cylinders under various conditions of speed and rates of expansion is a complex problem, due to variations in both the pressure and temperature of the steam at admission and exhaust, varying as they do at different rates of flow, and hence with different speeds and cut-offs. It is, therefore, natural that in the discussion doubt was expressed whether Mr. Diamond's estimates are well founded. That locomotive performance at high speeds has been greatly improved of late can be conceded, and in this connection the author's reference to the pioneer work by G. J. Churchward at Swindon in years long passed is timely. Recent improvements in cylinder design are entirely in accord with Churchward's principles, instigated about 1902. Modern designers may, therefore, take credit for following a path clearly marked out many years ago.

[Wizlish]

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...

[wanswheel]

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 22^nd 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.

 

Ernest Leontine Diamond will be remembered in the Institution chiefly for his work with the Standards Committee, on which he had represented the British Standards Institution since 1951. He was a man with a high standard of values and, although essentially patient and tolerant, was often impatient of trivial discussion and had been known to express himself forcefully when asked to undertake tasks which he felt to be of little moment. He established a relationship between the Institution and The British Standards Institution which was of inestimable advantage to both.

 

To his widow and three sons the Institution offers its deepest sympathy.

 

 

[sgriggs]

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.

[erikem]

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

[Paul Milenkovic]

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?

[sgriggs]

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.