Draughting arrangements for Bulleid Pacifics including the Giesl ejector

That's fair enough. Over to you now to prepare the spec, job sheet and financial package. Then maybe we can start talking.

 

I do find it odd the justification for getting a properly proportioned exhaust system can be so easily dismissed and yet a double chimney and the smoke deflectors thereby made neccessary are 'essential' to 4472. Lets face it its got more to do with avoiding change and or costs regardless...

 

I stand corrected Jos, my memory failed me.

 

Nothing of the sort. Do you own a loco?

 

Nothing to do with that. I know many heritage lines take quite innovative and modern approaches to areas such as infrastructure work - they have to, the financial health of the line may depend on doing so. What they don't tend to do is engage in potentially costly experimental work at significant capital cost in which the benefits are unproven and the likely long-term cost saving is small. In a cash-tight environment, if you are going to make significant capital investments, better to do it in areas where the pay-off is more certain and less based on having to act as an experimental guinea pig with uncertain outcome.

Tom

 

What makes you so sure of cost & outcome, do you know more than we do? I am just waiting for additional info.
Kind regards
Jos Koopmans

 

To take an example: On a heritage line I work on (a major one) the annual coal bill is about 6% of expenditure. Even if you could make, say, a 10% saving in coal, it would represent only about 0.5% of annual expenditure, which is in the margin. There are far more costly areas where an efficiency saving would have more benefit for less risk.

Tom

 

Not me, but I had already invited someone with the relevant expertise to tell us how much it might cost

That is a much stronger argument than coal saving.

 

I suppose the best way to look at an improved exhaust system is that it could be seen as a form of insurance in that it makes the performance of a locomotive more dependable.

This only matters for locomotives that are operated on the mainline. Preserved lines are by and large part of the leisure and entertainment business. Nostalgia and all that. If a locomotive performs badly, the train it is working runs late and the timetable slips alarmingly it is not as important as a mainline working where the delays and disruption brought about by one of our antiques performing badly or failing impacts on hundreds if not thousands of people who are certainly not out for the ride.

Yes, engines can fail in their task for many reasons. But to ensure that one potentially weak link is largely eliminated can be no bad thing. And if as an aside we can make the emissions of our heroes less offensive to those whose task in life is to eliminate all that might be seen as polluting and warming it could prove a good thing in order to try and ensure a future. We might be so small as to think of ourselves as insignificant. But our all too visible presence could make steam a very easy target.

 

I am answering my own message of over two years ago! In my case "a penny dropped" and I have recalculated the 29 BR9F 92250 Giesl test results. To my great surprise my revised momentum equation appears to give calculated results which
are on average 1% off the test results. Giesl is certainly flawed and by "induction" Porta also since both stated that momentum
of the gases should be taken into account which I did not do.
Kind regards,
Jos Koopmans

 

Hello Jos,

Does this mean that, with modern knowledge, it would be possible to design an improved Giesl, with the correct proportions?

 

Other exhausts are also available as they say. We at ASTT are currently instrumenting our successful Lempor installation on the S160 at the KWVR to validate our design method and tweak it if necessary.

 

Yes, it does, within limits. I think I have the proper version of the momentum equation and it reacts to geometrical design changes. That said, I am using diffuser data of 1971 and now have to look for more modern ones to cope for more
measurements.
Kind regards
Jos

 

I sincerely hope that such data are available to third parties. Since 1982 no proper measurements have been made public so we are just guessing about the "truth level" of the Lempor claims.
Kind regards
Jos

 

Jos,
Our intent is to instrument the loco sufficiently to not only verify the smokebox vacuum produced by the Lempor, but to record indicator diagrams as well. The sensors, datalogger and software have been successfully trialed on a narrow gauge loco so now we are moving forwards on the s160. Of course progress is regulated by the availability of the loco to run trials. The KWVR is a busy place, and quite rightly we have to fit in around their primary focus of running passenger services.

 

To help you with tweaking, I adapted the Saunders method for the pressure on the chimney wall by using diffusor data. It also dawned on me that the exit momentum of a diffusor alone is changed between an ideal and a practical diffusor. So the exit momentum is treated with an efficiency factor which is the measured pressure coefficient divided by the ideal one.
As a consequence the exit momentum is lower than the ideal version and in the case of the Giesl the calculated data dropped on top of the measured ones. (I did the same with some 400 data from other Rugby tests, results are within error margin).
Why I am telling this is that the lower exit momentum could also be the result of some subtraction of the entry momentum.
Since Porta describes adding entry momentum there is now a huge difference between the outcomes.
I am sorry if some of you do not understand this, since front-end performance is a fluid dynamics problem, one needs a little
understanding of the theory, for the last 15 years I have been trying to get rid of the black magic!
Kind regards
Jos

 

Fascinating thread, but as nobody has yet mentioned the most important railway preservation question of all - i.e. what colour these proposed modifications should be painted - I'm afraid I cannot take them seriously

 

So we wait with baited breath to see the results for better or worse of 6023. The reason that I have never released information on my work on lempors and beyond and won't is that it will be taken out of context. I have no intention of realising any more than I have.

 

That is an unusual approach to research findings.

 

I have to confess that I have no knowledge of your work on Lempor designs, but I wonder how much of it has benefited from the theories, research and findings of those who have gone before, and not been afraid of trusting others with their results?

One of the things I find fascinating is that, 50 years after steam traction technically became obsolete, efforts are still being made to improve performance and efficiency, using modern knowledge and techniques (is that unique to steam locomotives?). Of course if you have put in all the work and research it is rightly your decision whether or not to publish, but it does seem a shame if useful data is denied to current and future engineers.

Dave