I found these old videos on youtube and started putting together a playlist "Flow Visualization".
The concepts of laminar flow, flow stall, reverse flow, pressure vs velocity etc. are demonstrated. While this is done in a liquid medium and we are generally interested in gas, the concepts are presented clearly. I enjoyed watching these so much, I just had to share.
The segment below immediately made me think of the P-Channel, and so potentially adding to the theory of why it works. Where gas of higher density is added into the flow at the top of a lower density gas.
Fresh air entering the burn tunnel through the P-Channel is presumably cooler than the air (flames) already in the burn tunnel. This causes instability which provides for turbulent mixing, as shown below. Although, in our situation we may want the air to be preheated in order to prevent excessive cooling of the burn and aid in efficient combustion, it won't ever be preheated to equal temperature as the combustion itself. Thus the effect still has potential, in theory. Whether or not this actually has a significant effect, I don't know.
I figure this concept in combination with Peter's idea of the volatile gasses tending to flow at the top of the burn tunnel makes for efficient mixing and a nice clean burn.
I've embedded the video set to start at 23:05, where the example I reference is demonstrated-
Last Edit: Nov 15, 2014 3:03:38 GMT -8 by PNW Dave
For fuck sake mate! Whay haven't you dug that before!
Well, the sound seems to be a little wonky!
Thanks a lot anyway!
HA! I've only recently found these myself! But physics and conceptual understanding is one of my favorite late night pastimes. For anyone with similar interest, I highly recommend Richard A. Muller's course "Physics for Future Presidents" from Berkley, CA. (though not rocket stove related at all). All lectures from the course are available to view for free. I've seen every one since the 2006 semester at LEAST once, so long as it is Muller or Bob Jacobsen... I didn't care for the more recent lecturers. Here is a playlist on YouTube- Physics for Future Presidents
Yes, who ever did the video conversions did not compensate for differing video and audio rates, so the video progressively lags more and more behind the audio. In some places you'll hear the narrator describe something that won't be on screen for a few seconds. So it is good to keep that in mind while watching.
Getting grumpy with people who don't understand fluid mechanics. I had to research few other videos, here they are.
Despite the funnel end, this can well illustrate what the exhaust of the heat riser does.
This one is even better,
If you immagine what happens in, a T, the two blue regions are increased, even more turbulent, and the gases crashing on a flat surface instead of a sharp point, create even more turbulence. Mixing with the stalling blue adds more and more drag on the gases.
TexasGonzo: Sooooo glad I found this site! Its always rewarding to find such a super group of folks! To any and all, feel free to PM me anytime. Thanks for having me!
Mar 11, 2019 18:56:41 GMT -8
jlmtech: GADGET: CONSIDER USING A JET PUMP INSTEAD OF A BLOWER FAN TO INDUCE DRAFT; NO CLOGGING.
Mar 26, 2019 8:19:28 GMT -8
michaelegan: i am unable to open the sketchup files on my mac. I used sketchup a few years back but apparently the company now requires a subscription. does anyone have any advice/instructions on how to use the program or how to view pictures without spending money?
Aug 20, 2019 18:41:48 GMT -8
mannytheseacow: michaelegan: download AutoCAD student version for free... import .SKP
Aug 23, 2019 13:33:44 GMT -8
topbaza: hi everyone, been searching all over net and this is were i need to be i think!!
Sept 28, 2019 6:16:25 GMT -8
anounaki: Hi, why I cant upload photos when I make new tread to this forum?
Feb 28, 2020 2:09:40 GMT -8
ahansen: photos under 1 mb not possible?
Jun 4, 2020 0:09:21 GMT -8
belgiangulch: Photo's are possible. They must be downloaded elsewhere and the image url (adress) is copyied.
Sept 14, 2020 7:26:15 GMT -8
belgiangulch: While creating a thread click on the small picture in the banner above the reply. A box pops up, paste the image url in the box. Pay no attention to the huge list of numbers and such.When you finish and hit reply your post with pictures will come up.
Sept 14, 2020 7:29:27 GMT -8
deadstarsstillburn: Hi there. I was directed this way by folks on the Permies.com website and am hoping I can get some information on how a total newbie can get started designing, siting, building, and not-dying-in-a-horrible-house-fire with a new RMH in a 160-year old home
Oct 21, 2020 6:52:10 GMT -8
deadstarsstillburn: The people over there recommended either a 6" batchbox or an 8" J-tube. I don't know what those are but am going to try to figure that out. What I need is a blueprint that I can scale to fit the need for my house. I have something likne 5000 square feet
Oct 21, 2020 6:53:00 GMT -8
deadstarsstillburn: but I do not need to heat all of it by any means. probably only need to heat half of that, maybe less.
Oct 21, 2020 6:53:15 GMT -8
deadstarsstillburn: moreover, the house has 3 storeys (large attic) so I assume if I get very efficient heating on the ground floor, that will go a long way toward heating the upstairs as well, no?
Oct 21, 2020 6:53:59 GMT -8
BenAlexanderT: Happy new year everybody. I wish you the best
Dec 31, 2020 15:06:14 GMT -8
Solomon: Anybody in Southern Oregon, in Jackson or Josephine counties?
Jan 16, 2021 21:54:43 GMT -8
gnomedome: i realsie this is from 2009
Apr 14, 2021 8:30:44 GMT -8
gnomedome: i realize this is from 2009 id love to see the photos from this ..as im looking to build a sauna soon similar to this .... if anyody sees this post email@example.com..... the photos in this post did not show up
Apr 14, 2021 8:32:00 GMT -8
dcoyte: I am planning to use a cast iron heat exchanger out of a hydronic boiler set on top of my rocket stove, flue out the top. There will be a pump moving the water through the heat exchanger into an unpressurized 2000 gal tank. Any thoughts?
Dec 31, 2021 6:45:55 GMT -8