Since the energy of the exhaust gases is being used to propel the rotating blades, this will result in a small net loss of energy to the exhaust gases and thus further limit drafting despite any unlikely benefit to drafting of the vortex created within the small vertical space in the device above the stack. The vortex created would throw heavier particles, such as burning embers, to the side so that they are out of the way of the main draft flow and where they may either be collected or drop down the sides of the stack and back into the smokebox between exhaust blasts.

Regarding the Japanese rotary spark arrestor:

I can easily visualize how the intense and massive high pressure exhaust flow can spin the small turbine made like a vaneaxial fan, and placed perpendicular to the full exhaust flow. Certainly it would be capable of spinning the turbine at extremely high RPM.

But I have a hard time imagining how that straight-line, high velocity stream spins a turbine that then acts a centrifugal fan that diverts the exhaust stream into a spiraling flow. It seems to me that the exhaust either drives the blades as a turbine or the blades drive the exhaust as a fan, but not both.

Otherwise that tiny spinning blade rotor would have to abruptly turn the massive exhaust stream 90 degrees from its direction of flow, and at the same time, change it from a straight-line flow to a rotational flow, for the purpose of centrifugally separating the solid matter that may still be burning. This does not seem plausible to me.

If the intent is to separate the solids from the gas stream, why not just directly nozzle jet the exhaust stream into a helical, cyclonic flow?

But, maybe the purpose of this device is not to centrifugally separate the sold matter from the exhaust stream. Maybe the purpose is to have the spinning rotor blades act as an impactor to the solids in the gas stream. Maybe the impact is intended to disintegrate the hot particles so they lose their heat content by being pulverized into dust.

If the blade wheel is spinning fast enough; it could be designed to physically collide with every particle in the exhaust stream. And yet it would still let the exhaust stream pass through with very little diversion from a straight line. So, with that concept, the blade is not trying to throw hot particles out of the exhaust steam to avoid emitting them from the stack. Instead, the blade is crushing each particle by direct physical impact. Crushing each hot particle to dust, causes the dust to disperse into the exhaust stream, and lose its heat content as its mass disintegrates and disperses.

I would love to see a test of the Japanese device. One can imagine that toward the end of steam such a device could have worked well but come too late to be worth the investment and not been adopted in the US, England etc. I understand the skepticism for gadgets on a proven technology, but at the time the cost/benefit analysis didn't factor in yuppies who wanted to shut down a railroad unless it comes up with a million godzillion dollar bond/insurance policy. I am exaggerating now, but as someone who lived in Colorado for a dozen years I really think D&S may be fighting a losing battle in the long run and if this thing works it could save them some grief.

As predicted, let the subrogation games begin...

https://www.google.com/url?sa=t&source= ... Vp&ampcf=1

Apologies for beating on a seemingly dead horse;

Having done some research since my last post on this thread concerning Japan National Railroad's rotary spark arrestor, I subsequently found out that D&SNG's current spark catching mechanism employs water jets to douse the sparks. This is a feature that is absent in the JNR system.

If anyone can enlighten me with the details of the D&SNG spark arrestor and its inner workings, it would help me to understand further the difference between it and the JNR system, and the consequent pros and cons of each spark arrestor.

Specifically, I am curious to see if the D&SNG's arrestor employs the same rotating fan concept. If not, a combination of the JNR rotating fan and D&S water spray may make for a more effective spark arresting mechanism, although presumably at the expense of impaired drafting and more cinders to clear inside the smokebox after each run, which seemed to be the case with JNR (some reports indicate 2.6 times more cinder buildup on a given run).

-Shogo

https://durangoherald.com/articles/40831#slide=0

Caption:"Steve Lewis/Durango Herald. John Harper of the Durango & SIlverton Narrow Gauge Railroad & Museum said spark arresters, which employ a screen and small water nozzles on the stacks of the steam engines, reduce the chances of hot cinders escaping and starting fires. Engine watchman Robin Schanbarger looks over a train returning to the station on Friday evening."

It would seem that D&SNG has thrown in the towel regarding coal-fired locomotives, what steam remains will likely be oil fired. I would have liked for them to experiment more with spark arresters from the late steam era such as the Japanese model you posted before, instead of such drastic changes as converting to oil (much less the purple and orange diesel I posted a photo of a few days back). But I lack the technical knowledge to be offering any advice on steam, free or otherwise.

The latest:

https://www.outtherecolorado.com/news/f ... 11cc2.html



More at the link.

It sounds like D&S did not realize that if they did work on their right of way that went beyond routine maintenance, they were required to first notify the Forest Service and learn whether the work was permissible and whether it required a permit.

Has it been determined that the clearing work went beyond routine maintenance?

How essential to the objective of fire prevention was the removal of the large, mature trees that were sold for timber milling?