The flow Reynolds number with the stove diameter (100 mm) as the characteristic length is Red = qVd/l = 4 m/pdl = 301.4. This is very small compared to Recrit (for transition to turbulent flow) for flow through a cylindrical duct constituting the combustion chamber. But there are 18 jets coming into the cross-flow and the critical Reynolds number of jet is small. Reynolds number based on jet diameter and the mass flow of secondary air is Redj ¼ qVd=l ¼ 4m_ air=pdl ¼ 391. Even if at this Reynolds number, the jet could be turbulent. But the jets are issuing into a chamber that has a high viscosity (due to high temperatures in the combustion chamber). The net behavior is close to laminar flow – the physical appearance is of a mildly dancing diffusion flame.