On yet another technical subject, the Kordina is a junction of two flows of gas into one, made in such a way that when one input flows, a suction is created that allows the other side of input to be "helped" along its path, assuming I understand it correctly. I'm finding it mentioned in passing in a lot of the literature I'm reading now......generally, incorporated as part of the front (or under front) end where both sides of the exhaust join to become one under the nozzle (much as the oceans of the world are formed where the Allegheny and Monongahela rivers meet, but that's another matter.)

What I don't yet understand yet is how it works and how to design one. I presume based on the assumption of it as common knowledge it is basic to engineering education, and I'm an English major, so.......yet another useful thing I missed. I also want to know if it was SOP to design sadle castings such that it was an integral part of the way they were cored, or if it was not considered as part of saddle exhaust passage design in standard US steam made in the early 20th century.

I know the brain trust here has people who can explain this clearly, and perhaps provide links to useful information.

dave

OK the 5AT.co.uk web site section on modern steam principles has some information on this = the exhaust passages narrow to the same area as the exhaust nozzle just below the pint at which they join together, if i read it right. the subsequent expansion is supposed to prevent choking of the flow such that the steam flow through the Kordina, then the nozzle, acts as an ejector pump and sucks out the flow from the next exhaust, preferably from the other side if the valves are in good order. There's a very good image there showing it in 3D on 2D........

I'm wondering how one best decides about the diminishing rate of the passage itself? Whatever's convenient?

dave

Dave- Sorry I didn't see this thread earlier. I think you've got the basic premise right in your second post. With a properly designed Kordina, the exhaust from one cylinder pulls a vacuum on the exhaust passages from the other cylinder, so that when the valve for that cylinder hits the point of release the exhaust steam can flow more freely. I don't know if there is any more detailed information on how to design and apply a Kordina than what you've already mentioned.

Porta and Wardale both experimented with making the wall of the Kordina curved in an effort to induce a swirled flow of the exhaust steam as it exited the nozzles and traveled up the stack. The swirling steam flow would promote more thorough mixing of the exhaust steam and combustion exhaust gases which theoretically makes the whole exhaust system work more efficiently.

With normal Lempor exhaust nozzles, I believe this won't work too well as the 4 straight exhaust nozzles downstream of the swirled Kordina would just re-straighten the exhaust steam flow, canceling what was accomplished by the swirled Kordina. Apparently this thought occurred to Porta too as some of the last Lempor exhaust systems he applied on the Rio Turbio railway in Brazil have the Lempor exhaust nozzles skewed so as to direct the steam into the stack with a swirling motion. You can see some good photos of the exhaust nozzles and Kordinas on these engines on this page on my website:

http://www.trainweb.org/tusp/sergio/ter ... stina.html

I suspect this was the basic premise of the Lemprex exhaust system, which Porta was supposedly developing at the time of his death. IIRC, the Lemprex exhaust is mentioned in Porta's paper that he sent to the A-1 Trust in the UK; this paper detailed Porta's thoughts on how a much more efficient steam locomotive could be built within the basic outline of the A-1 exterior. Shaun McMahon may know more about the Lemprex system.

The basic ideas and concept of the Kordina is correct as you state them. The technology as in the public domain still has alot to be desired. The S shaped swirl is not a sucsses as if to close to the nozzle it sends the exhaust up only two nozzles.
The nearest I can easily describ a good arangement is used on car exhausts, Try looking at some sports car exhaust manifolds.

The Lemprex was built a few times and I have never heard any conection made between it and Kordina theory. The angling of the nozzles was more related to the action withing the difuser of the Lemprex.

Nigel- that makes a lot of sense. That's the basic intent in the exhaust collector on aftermarket exhaust headers. The exhaust from one cylinder induces a vacuum in the exhaust pipes from the other cylinders, making them all flow more efficiently.

Dave- more info on Kordinas on the 5AT website:

http://5at.co.uk/index.php/modern-steam ... rdina.html

Meineke and Roehrs, Die Dampflokomotive, discuss the original tests with a Kordina in the form of a concentric junction of the two exhaust pipes. It did not work. In general, unless you find convincing evidence in the form of measured data, do not believe all these claims.
For you, our american brethren, your Prof. Goss did supply you with some useful data. In the Proceedings of the Master Mechanics Association of 1896 he wrote the Report on Exhaust Pipes and Steam Passages. In it is page 87 plate 14 where flow separation between the left and right cylinder flows is arranged for by a vertical plate of different heights. The vacuum remains the same, the back pressure goes up from 1,25 to 1.4 psi and his "efficiency" goes down from .088 to .078 when the separation is diminished in height from 12 to 4 inches.
So careful guidance of left and right flows is quite useful.
Kind regards&seasons greetings
Jos Koopmans

I would point out that Dr Koopmans' PDH dissertation was on steam locomotive exhaust design, and has been published in the book "And the Fire Burns Much Better....."

Thank you for joining this thread with a great bit of information.

Does anybody have access to the Goss reference mentioned and can perhaps scan it and post it here?

dave

I have a photocopy of Goss' work, part of the original homework. I can try to upload a scan tomorrow, it may take some time since I have to learn to upload here first, so bear with me.
Kind regards
Jos Koopmans

Let's give it a try:


Kind regards
Jos Koopmans

Perfect, thanks Dr.

Left to wonder if any of the modern Kordinas has real measurements done to verify their permormance?

dave

Hi Dave,
You are welcome!
I doubt about any Kordina measurement. If they were done, the results are buried in a number of simultaneous changes/improvements. There is a chance that the highly educated boffins of the 5AT group have done some CFD modelling.
Kind regards
Jos Koopmans

There are definitely some similarities between internal combustion engines and steam engines. A lot of time and money is spent streamlining and equalizing the lengths of passages and getting flows close to parallel when they converge or diverge. Look at any Edelbrock or Banks Engineering product. Like many steam locomotive functions, there is undoubtedly complicated science behind things you can approach empirically if needed. I would look at modelling and using a flowbench similar to automotive -type flowbenches. With modern instrumentation and manufacturing now available inexpensively, one could test a variety of designs with very high accuracy.

The difficulty I have encountered and Mr. Porta tries to hammer home is that almost no single improvement will achieve the desired effect. Perhaps the front-end is most responsive to improvement. The answer I have heard and experienced is that we must first get back to 1930 before we can move forward. That means you cannot see over the top of the piston rings, have valleys in the valve cages, nor be able to freely bar the valve gear back and forth. Even then, you are held back by what you have to work with. The 8055 and 1816 projects are good examples of hitting these limitations. I think the 5AT and particularly the 8AT are good efforts for a fresh start and exploring the capabilities of the Stephensonian design.