Here is what I have learned about a makng a stove burn as a gassifier.
It has to have two zones,
one zone where the wood is cooked to slowly release the gas.
The other a very hot zone where the gas (smoke) burns.
This can be done if the wood is stacked vertical and burned from the top down. The top supplied with good draft directed at the flame. The bottom deprived of oxygen, only getting enough to cook the gas out of the wood.
The smoke from the bottom will put the fire out on the top if the fire on the top is not hot enough. Small stuff has to be added until it burns hot enough. You should always see flames on the top. My stove is closed on top, draft comes in at flame level. The smoke exits out the back. There is a draft opening at the bottom that is closed or almost closed. I have not experimented much with a stove with an open top.