We need to be careful as to whether we are comparing “apples to apples”.

Still air speed is not like throwing a liquid fuel toward a “crackling” fire.

In mining school it is common to show a film where 5% methane in still air burns sluggishly
10% methane “explodes”
and 20% methane burns sluggishly again.

It is hard to believe
but in my great-great grandfathers time
each mine had a “Fireboss”
whose highly paid job was to go in and burn off the methane ( aka fire dampf) in the tunnels.

Near Newcastle a mine manager went out of his way to take me to a huge fire bricked chimney room in a very old coal mine where instead of using a propellor fan (not yet invented yet) a huge fire was always going to “induce a draft of air” through the tunnels. The manager told me when the methane emission was high the fire burned without any coal. The flames did not spread back into the tunnels because of copper “quench curtains.”

Here is a scientific report about flame speed in still air.
1 foot per second would be about 32 cm per second.
Scroll down to the graph
“Laminar Flame Speed cm/sec on the left axis
and “Equivalence Ratio” on the right axis.

https://www.sciencedirect.com/topics/engineering/laminar-flame