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I had written before about opening up the water supply for my Aster Jumbo that had a poor performing axle pump.

http://www.mylargescale.com/Community/Forums/tabid/56/forumid/11/postid/78783/view/topic/Default.aspx

I have received a new tender-engine water connector and installed it. It has a cross sectional area of over 3 times the original connector. I wanted to check the pump out again so I took the engine out to my track for a check. This morning it was about 40 F and the wind was blowing. The engine would hardly make enough steam to get out of its own way. Remembering that I had put a baffle under the fire box on my Aster Schools to reduce the excess air flow, I put some small pieces of aluminum foil in the bottom of the firebox to experiment with reduced air flow on this engine. What a sucess. The fire starting roaring and I could not stop the safety valve from blowing. (This was just a test run without coaches behind.) And, there was no bad unburnt alcohol smell. I assume that the reason that I have not had this problem before is that I have been more selective of the temperature and wind conditions. At warmer tempertures and lower winds, the excess air flow does not hurt the performance enough to notice.

What this shows is that air flow into our alcohol fired engines need experimenting with just like we experiment with the wicks. I wonder how many times we have tried to figure out the proper wick heights or consistency without thinking about air flow. It may be worth while to experiment with aluminum foil to get the maximum flame from a minimum size wick. When we get good flame and little smells, make a more permanent air reduction fixture. We need to experiment with the air flow in our gas burners (possibly for different reasons,) so experimenting with alcohol burners should be expected.

Dan
 

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Dan,

You are correct that it's an area for experimentation.

I did similar experiments on a 2-wick alcohol fired vertical boiler that would not make steam. The bottom of the firebox was completely open and allowed cold air to flow right up into the single center flue. Making an aluminum baffle that fit loosely into the bottom of the firebox and had two holes for the wick tubes went a long way toward getting the boiler to steam. The gaps around wick tubes provided sufficient air for combustion since there was no forced draft.

On an experimental C-type boiler with a forced draft I tried a baffle arrangement for the bottom of the rectangular smokebox. The forced draft caused vortices to form adjacent to the flames, which caused the wicks to burn unevenly and noisily. I increased the size of the openings around the wick tubes to get the flames to burn evenly, steadily, and quietly. Eventually the holes became a single oval hole for both wick tubes.

Steve
 
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