How does the double combustion of a wood stove work?

Here's how the double combustion of a non-catalytic wood stove works (EPA):
1. The pull generated by the chimney allows the intake of fresh air through the openings in the unit.
2. The primary supply of air injects oxygen onto the embers and wood.
3. This causes the fuel to burn, which releases gases and fine particles.
4. Secondary air introduces oxygen into the hot gases released by the first phase of combustion.
5. This causes a second combustion above the wood that burns almost all the fine particles and noxious gases before they are evacuated through the chimney.

[@victoryfirst2878]

Nice explanation of the process. Please do another one on a catalytic stove.

[@glennlopez6772]

Having watched parts 1 & 2, it seems that its just a text explanation on the subject.
It would be nice, if a cross section of the stove was shown, specially for the secondary air.
Additional views woud also be required!
Thanks anyway!
So we could see the path the air takes!

[@sorrykay3450]

But where is the secondary air coming from. It's all closed at the top

[@leofortey7561]

From the back or sides. It is fresh air that gets heated by the flames, sending hot oxygenated air to the top which helps burn excess wood gases that would otherwise go up the chimney.