[Stoves] SPAM burning wood gas

Sun Jul 18 18:24:45 CDT 2021

Hi Kirk,

You've put a lot of work into the designs of these! I like the wing/rudder shaped profile of the pipes in the top right one in the top picture. As well as it's fold-not-weld to make it a cone.

I know you've used a fan shape to swirl in some of earlier designs, I remember seeing a slot in a horizontal pipe secondary air inlet, with a non-moving fan directly above. Have you tried fan type blades around the external of the bluff body? Or was the swirl discarded as a lesser form of mixing than the Venturi effect? Would both together be of benefit? The centre one in the bottom photo looks like it would not be far from a fan blade, though it looks flat not coned from what I can see.

The one I am working on when I have time has an air forcing stand below and a removeable fuel canister, a little like Paul Anderson's FAB Stove only bigger, to use for home heating. It has a central secondary air inlet, a pipe up the middle, which also heats the air. I have a flat disperser from a portable outdoor gas heater, which I will build a cone underneath, so it will dispense the air in jets from the outer top edge of the cone of the bluff body. That is the current plan anyway. Current thought is to try to work in a swirl. We shall see... Work in progress...

Daniel
________________________________
From: Stoves <stoves-bounces at lists.bioenergylists.org> on behalf of Harris, Kirk <gkharris316 at comcast.net>
Sent: Sunday, 18 July 2021 4:53 AM
To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>
Subject: Re: [Stoves] ***SPAM*** burning wood gas

Daniel,

Thank you for your response and question.

Currently I am experimenting with various configurations for the bluff body.  A trailing edge is one possibility to try.  The flat top bluff body causes vortexes directly above it.  The vortexes do not seem to help or hurt in the overall performance.  A trailing edge might eliminate most of these, and perhaps could reduce flow resistance.  Using descending tubes from the bluff body (as I described in an earlier contribution) to let air enter the interior of the flame above the bluff body seems to reduce the vortexes and feed air to the interior of the flame as well.  This helps with both high and low power levels.

Attached are photos of some of the bluff body designs I have tried.  They are upside down in the photos.  The ones with "petals" are intended to create rounded lobes of flame, and the partial tubes create a narrow open space between the lobes of flame.  This may (I don't know yet) allow air into the interior without the tubes.  Both tubes and partial tubes seem to perform similarly, and help enable the very high and very low power levels.

Were you thinking of a cone shape for the trailing edge?

Kirk H.

On 7/16/2021 8:03 PM, Daniel Pidgeon wrote:
I love your work, Kirk!

I quite liked the details I saw in the spec sheet of the three hour TLUD you put out a while back, and am looking forward to putting a few concepts from there into a build, when I can get to finishing it.

Since childhood I have admired the impact a wing shape has on the air around it and been interested in flight, and was intrigued by "the Venturi effect" that you talk about which I had never heard of before reading your work, but it only just struck me today that the two are very connected. Just spitballing as I go, would there be merit to your "bluff body" having a "trailing edge" like a wing does, rather than just a flat top? I have nothing to go on asking this, and no suggestions, just a thought that occurred. I don't know how much harder this would be to make.

Daniel
________________________________
From: Stoves <stoves-bounces at lists.bioenergylists.org><mailto:stoves-bounces at lists.bioenergylists.org> on behalf of Harris, Kirk <gkharris316 at comcast.net><mailto:gkharris316 at comcast.net>
Sent: Saturday, 17 July 2021 5:50 AM
To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org><mailto:stoves at lists.bioenergylists.org>
Subject: [Stoves] ***SPAM*** burning wood gas

All,

I have been working on a document on a subject which is quite
fascinating to me.  I thought I would share it with you even though it
is unfinished.  It probably will never be finished as I find that each
idea leads to more ideas.  I might as well share where I am now.  As I
proceed, there will be more drawings and photos of the test stoves and
components.  I hope there will be questions because questions make me
look at things I have not paid attention to before.  Dean Still's
questioning has been very helpful.

I hope you enjoy it,

Kirk H.

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