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Draughting arrangements for Bulleid Pacifics including the Giesl ejector

Discussion in 'Steam Traction' started by jamesd, Oct 14, 2014.

  1. Jimc

    Jimc Part of the furniture

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    Worth remembering that the task of presenting raw data in a form that is readily communicable and not subject to misunderstanding or being taken out of context is a major task and skill set in itself.

    One might speculate that is why much of what we have from the steam age appears (to this inexpert viewer) to be rules of thumb and design guidelines rather than complete research papers.
     
  2. Jamessquared

    Jamessquared Nat Pres stalwart

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    Possibly, though I would also suggest that trying to do verifiable, repeatable scientific work while accurately controlling variables in a very complex multi-variable environment is a considerable challenge. Bear in mind the dearth of controlled-testing plants; even relatively simple (in the grand scheme of things) items like dynamometer cars were few and far between - you could argue that the historic railway companies should have invested in such items, but ultimately they didn't. Instead, you mostly get indicator diagrams taken while a loco was in traffic, and maybe some attempt at measuring coal consumption, all against a background of varying loads, weather conditions, on roads that were far from level, slotting in (and subject to delays from) other service trains, coupled with fairly primitive instrumentation etc. etc. The scientist in me wants to throw up my hands in horror!

    That said, the old railway managers weren't mugs: one assumes they had a fairly shrewd idea about where worthwhile savings were to be made, and where not, and presumably in most cases, thermal efficiency ranked lower than the ability to move the trains with high availability. Given the opportunity to optimise a class of locos so they were best-in-class at per mile repair costs; or best-in-class at per-mile coal consumption, in most cases improving the availability and per-mile repair cost gave much greater scope for savings - a point notably demonstrated in the Bulleid pacific rebuilds. Going back a few generations, Beattie was justifiably proud of the marked thermal efficiency of his various coal-dodging inventions, while drawing a discrete veil over the cost of firebox repairs and others in his complex fireboxes. Adams took one look at them and replaced the lot with simple, dependable, conventional locos...

    Tom
     
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  3. JJG Koopmans

    JJG Koopmans Member

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    When I was a university student in Delft and training to be a naval architect what was taught in the sixtees was also rule of the thumb experience with a scientific sauce applied. Those were the days of slide rules and applying earlier experience. I do not think that any other engineering occupation was much different! One of the reasons that I felt attracted to front-end research was that it was unfinished business with 150 years of constant attention and a lot of expensive effort to get the gist of it.
    Kind regards
    Jos
     
  4. JJG Koopmans

    JJG Koopmans Member

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    In the mean time I have written a description of the changes to the momentum equation with calculated proof submitted.
    The SLS Journal has accepted the article, so some time in the future you can read it there and try to falsify it!
    Apart from that I have modified the BR 9F Giesl calculations to accept changes in the geometry. Increasing the ejector dimensions allows
    more gas to be ejected, but that needs a higher vacuum which nullifies the increase. Apparently our dear professor Giesl knew what he was doing.
    As an example here is the overview of the Giesl. I received 31 datasets of which 29 could be used. Since a number of them had steam consumption
    within 1% of each other I have averaged the results making the graph more clear.

    [​IMG]
    The second graph shows all the data of the 9F double chimney together with those of the Giesl.
    [​IMG]
    There appears little difference between the double and the Giesl performance. The Giesl had 120% exhaust area of the 2x4 in. orifices of the double.
    Gieslcalc.jpg Giesldouble.jpg
    Kind regards
    Jos Koopmans
     
    Last edited: Mar 29, 2017
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  5. Courier

    Courier New Member

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    guess you've seen this before - but just in case you haven't and it is of interest....
     

    Attached Files:

  6. JJG Koopmans

    JJG Koopmans Member

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    Thanks, I have not seen that one. It used to be very difficult to plow through different magazines.
    Now that they are on line it is better, but it appears to cost money!
    Kind regards
    Jos
     
  7. Courier

    Courier New Member

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  8. JJG Koopmans

    JJG Koopmans Member

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    Thanks, please enlighten me, is there a difference between plough and plow?
    As for the references, I used them to locate the most original description of the Kordina part
    of the exhaust system that the Lempor people use so erroneously.
    Kind regards
    Jos
     
  9. Jamessquared

    Jamessquared Nat Pres stalwart

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    About 3,000 miles of North Atlantic Ocean ...

    Tom
     
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  10. JJG Koopmans

    JJG Koopmans Member

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    Ok, got it, sorry! One has to be very careful these days!:)
    Kind regards
    Jos
     
  11. Monkey Magic

    Monkey Magic Part of the furniture

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    A fascinating thread, I have a question - does anyone have any experience of firing or driving 34092, 78022, Edward Thomas or even Linda in her Lempor days, and how do they compare to unmodified west countries, 78000s, or Edward Thomas or Linda without their mods?
     
  12. Steve

    Steve Part of the furniture Friend

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    I've experience of driving 34092 and other Bulleids and, at heritage railway speeds, I've not noticed any difference. I've also experience of firing TR No.4 in both guises and, although it was a long time ago, honestly preferred the conventional blastpipe and chimney arrangement. It always seemed easier to make steam in that condition although it's quite possible my firing skills had improved.
     
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  13. ragl

    ragl Member

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    There was a terrific and well researched article in Railway World back in the late 80's with lots of juicy data covering the application of the Giesl Ejector to 34092 and the increase in performance that was obtained. IIRC, the increase in power was similar to that with 34064 Fighter Command back in the 60's, as in, it was considered more class 8 than 7, another big plus with the Giesl was the savings in coal and water.

    I remember witnessing the exploits of 34092 back then; for me, the big takeaway was the vast improvement in the audible part of the entertainment, I will always remember that wicked, rasping exhaust on the climb to Clapham; Giesls should be made a compulsory fitting to all Bulleids.......

    Must get up to Bury for some more Giesl action soon.

    Cheerz,

    Alan
     
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  14. JJG Koopmans

    JJG Koopmans Member

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    Please don't! There are better and cheaper solutions available since 1954.
    Kind regards
    Jos
     
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  15. class8mikado

    class8mikado Member

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    Perhaps the potential price rise/scarcity of coal of the right quality will finally provide the impetus for these efficiency improving measures
     
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  16. 242A1

    242A1 Member

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    There are many more factors that ought to be considered in addition to the exhaust system. The rewards for addressing these can be substantial, see the Bure Valley thread. We are not talking about irreversible changes and we do not have the excuse for not knowing that these options were available.
     
  17. meeee

    meeee Member

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    I've fired and driven Linda both with and without Lempor but not on the same fuel. I'd say that is much more free running now with the single blastpipe. The lempor seemed to hold it back.

    Steaming wise it is difficult to compare. Linda needs careful handling both on coal and oil. Big cylinders and a small grate are not the best combo on an engine working that hard. A crew who know it well will have a great time with it though and have no trouble with steaming. The main issue with the single blast nozzle is it will lift a thin fire if you're not careful.

    Those who fired it on the gas producer system speak very highly of it. I believe the main issue was getting the right kind of coal.

    Blanche also had a Kylchap cowl before conversion back to coal. You'd struggle to find anyone who misses it.

    Tim
     
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  18. Monkey Magic

    Monkey Magic Part of the furniture

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    I fired Linda on oil just before the rebuild back. It was not in good shape. We had leaky tubes - to the point where Evan Davies failed it after the first trip.

    The Alco also had a different draughting arrangement at one time as well (around the same time I think).
     
  19. ragl

    ragl Member

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    Hello Jos, I can assure you that my tongue was firmly planted in the side of my cheek with that particular quip.......

    However, Giesls do sound good tho'.........

    Cheerz,

    Alan
     
  20. Monkey Magic

    Monkey Magic Part of the furniture

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