Hi Toymaker, Yes there are a few answers. But these are my knowledge, and a proper burner engineer may have better answers. It does look like you have good atomisation, but I think you need more air within the cloud. (The mixture ratio is too rich).
My SIMPLE understanding is as below: (I say simple, because I am NOT a combustion engineer, just picked-up a few bits on the way, and I am probably incorrect in some of this?!)
The initial Fuel air mix must be heated to a point where the hydrocarbons begin to breakdown into ions, so the fuel ions (carbon, Hydrogen, and simple paraffins, butanes, etc.) can combine with the O2 => Oxygen ions from the air. So, because of the mix of Oxygen and Nitrogen making-up air, and the natural combinations of carbon and hydrogen in the hydrocarbons we are burning, you need about 15 times more air than fuel to balance most of the fuels we are burning here.
In flames, the hydrogen ignites and burns first, as it is so reactive, elevating the fuel and ionised gas temperature of the "Mass" of the mixture. This can be initiated in a small local zone by a spark (electrical, flint, iron, or whatever!), where the "gas temperature" to make the first ions to start the combustion is a few thousand degrees C. Once initiated, the heat released from the first few burning ions rapidly ionises the rest of the mixture nearby until a sustainable flame occurs. The heat at the flame front: where fresh mixture meets the combustion zone, keeps ionising more fuel which mixes with ionised O2 from the air to permit more combustion. This is my "simple layman's model of the flame.
When the hydrogen has been ripped off some molecules of fuel, the carbon ions mixing with Oxygen ions combust around 500degrees C or higher (?) forming CO. But there can be free carbon that is "quite big" relatively in molecular/ion size within the fuel gas mix, if there is insufficient air (oxygen) in this initial mix of fuel and air. This free carbon must be heated to glowing (over 700 degrees C?) with more air in order to burn to CO.
In a third phase, all the remaining CO and C burns with the remaining air (a darker blue flame, tinged with yellow or orange where there is free carbon). But as the flame is rapidly expanding, and, because of gas laws, that means cooling, when the temperature drops below around 700degrees C the carbon stops burning (leaving free soot), and when it drops below about 350 degrees C the CO stops burning.
A crazy thing I found is that when I get enough air into the mixture initially, the flames get smaller and more compact (actually are hotter as they burn faster). When you reach a stage close to "good" complete combustion, the "yellow feathers" reduce to an orange glow in the flame, and then disappear leaving just the 2 blue Bunsen cones we are familiar with.
So I still think you need MORE air in the jet nozzle.
I.E. use a smaller fuel jet and a higher air pressure, until you get a better mixture here.
You are pumping 14L of fuel per hour through the jet: This is 14 x 0.8 /60 = 187gms of fuel per minute.
Which means you need 15 x 187 = 2.8 kg. of air per min. = 6.172lbs of air per min.
Dry air at 0�C has a density of 12.417423770565761 cubic feet per pound. So you need 76.65CFM at atmospheric pressure. At 100 psi from your compressor, that equates to 9.82cfm.
What pressure are you delivering at the jet? What air flow rate do you have at the jet?
When we understand the Mixture is correct, then we can tackle any "flame dynamics" to resolve any issues. But I think your blower and nozzle outer giving the swirl pattern is probably good.
An idea: Can you fit a jet of maybe 3/4 the diameter (size) of your jet, and increase the air pressure to 1 1/2 times the current pressure? Then let us see what that does?
If my help is "no help", just tell me to stop. I am no expert, just a meddler in this subject.
K2
