Some Interesting Experimental REsults

[Beth]

Re: Re: New Question

That depends on the type of sensor that you're using (thermocouple, infrared, etc.), but the most common effect of soot covering the sensor is a lower temperature reading than reality because of the insulating effects of the soot buildup. However, since these are pre-preliminary types of testing, I suggest you try both tests (with or without concentrating) and seeing if you have any different readings. Also, you shouldn't be too close to te flame because your presence may also move the flame slightly.

Thermocouple. I suspected as much about the soot. But rather than trying to quantify it's effect, I think I will attempt to eliminate it. Thanks for your thoughts.

Beth

 

[Beth]

Beth,

As you may recall, I suggest the thermocouple apparatus to you some time ago, after trying it out in my own kitchen (I have one readily available to me).

Yes, I recall. In fact, your suggestion was what led to my moving to this equipment.

I'm sure you thought of a lot of this already, but I hope there was something in there that was helpful.

Yes, thanks.

Beth

 

[IXP]

Beth,

Thank you for posting your data.

Earlier, when you originally joined the forum, I tried some experiments with a candle in a glass with a ring covering part of the top of the glass (the ring was made from wood, since this is my hobby, and I had no wax rings handy).

I was surprised to find that the flame behaved chaotically with this setup whereas the same candle, unprotected, burned with a very stable flame as long as I stayed far enough away from it.

Here is what I think is happening. In order for the candle to burn, given your setup, gasses must flow in two directions through a single small round hole (about 1 1/2 in diameter, in my case). Air must enter to provide the oxygen for combustion, and combustion gasses must exit. This is not going to flow smoothly and leads to the chaotic flame behaviour.

I think your flame would be much more stable if you protected it with a chimney of glass (like from an old hurricane lamp) that is open at the bottom and top. This allows the gasses to flow in one direction only.

A stable flame should make it much easier for you to sort out any influence you are having on it.

IXP

 

[Beth]

Beth,
Here is what I think is happening. In order for the candle to burn, given your setup, gasses must flow in two directions through a single small round hole (about 1 1/2 in diameter, in my case). Air must enter to provide the oxygen for combustion, and combustion gasses must exit. This is not going to flow smoothly and leads to the chaotic flame behaviour.

I think your flame would be much more stable if you protected it with a chimney of glass (like from an old hurricane lamp) that is open at the bottom and top. This allows the gasses to flow in one direction only.

A stable flame should make it much easier for you to sort out any influence you are having on it.

IXP

Thanks for your input. I hadn't thought of the upper and lower openings as making a difference in the way you describe, but now that you've pointed it out, it seems quite obvious. The vase I've using now is 3.5" diameter and I'm not placing anything over the top of it. So the opening is larger and an oil lamp (or alcohol as has been suggested) will burn more steadily than a candle.

The concern I have is in regard to inadvertantly influencing the flame physically. I work fairly close to it and I use hand movements. Neither of these is something I can forego, which is why I place the flame inside a glass container. Do you think having an opening at the bottom as well as the top would make it more or less likely for me to inadvertantly influence it?

Beth

 

[IXP]

Beth,

I don't know whether it would provide better or worse isolation, I did not try it since I did not have such a thing handy. I do think it would be worth trying.

I did not recall that you used hand movements. Why is this necessary if you are influencing the flame with your mind?

IXP

 

[Zep]

The concern I have is in regard to inadvertantly influencing the flame physically. I work fairly close to it and I use hand movements. Neither of these is something I can forego...

I would respectfully suggest that a very unstable system like a candle or oil-burner flame, which depends on many factors for its shape, including it's own consumption of available oxygen, uneven fuel flows, chaotic convection air currents from its own heat, variable transferred heat from the container, and any turbulence created by constricted air-flow situations in a cup or vase, would be easily influenced by the simple movement of nearby air from hand-waving, or even just the heat of your presence.

Another test I would suggest would be to record results for your flame-influencing movements but with no flame lit. That way you may get a measure of how much your setup is suceptible to quite mundane effects not to do with the test subject (i.e. the candle).

I would suggest that if you want to get reliable results, you need to work at eliminating or at least controlling and enumerating all these known factors, before considering other unknown explanations. As you have already noted, it's not as easy as it appears!

I would also suggest you analyse what is actually happening here. A flame is a highly unstable phenomenon anyway, even steady flames have notable variations. Perhaps you might like to consider trying to "influence" some other more stable (and less dangerous?) equivalent - I'm sure the physicists can provide you some practical examples. I thought of cigarette smoke rising in a wide, long tube. Or really fine dust drifting down the same tube.

cheers

 

[IXP]

Beth,

I have been thinking about this some more, and, like Zep, I suspect that with the unstable system you have set up, very small hand motions could physically affect the airflow and therefore the position of the flame.

I would suggest that you isolate yourself from the flame in a different manner. Use a large sheet of plexiglass between you and the flame and leave the flame in the open (no vase or chimney). The plexiglass sheet should be large enough to make keep the motion of your hands from creating air currents that affect the flame. I would think the barrier should be a minimum of 3 ft square to adequately do this. You can check this by setting up the candle noting it stablity, then waving your hands behind the sheet (without and intent to influence the flame). If the candle is not visibly affected, this is a good starting point.

IXP

 

[MRC_Hans]

Elaborating on Zep's comments on the unstable chaotic system, still respectfully: This is the typical structure of all the systems we see and are skeptical about. They contain some kind of chaos (or noise) generator that enable them to generate an essentially random output that can be easily influenced or even interpreted.

In the case of Beth's experiment, the flame is an intrinsically chaotic system, and putting it into a vase or other container makes it more chaotic, since we now not only have hot air convecting up from the flame, but cold, fresh air being sucked down around it, creating a chaotic, turbulent boundary layer. The heat sensor is both measuring the heat conducted to it from the turbulent air-stream containing warm and cold air, but also by radiation directly from the flame.

It is entirely probable that this system is so sensitive that the mere presense of a person beside it will make a difference.

Thus, it is very important to reduce the chaos in the system. First of all, the container must allow air to enter at the bottom, so there is a reasonably laminar airstream going through the glass. And, as I mentioned, you should employ differential measuring, so that changes in the total temperature in the system become uncritical. Time must be made uncritical by a randomized sequence, and observer bias must be eliminated by blinding.

Hans