Propagation velocity and flame stretch measurements in co-flowing partially premixed flames with widely varying premixedness

摘要: Abstract The present investigation focuses on the flow-field upstream of co-flowing methane–air partially premixed flames stabilized in a splitter plate burner, with wide variation reactant concentration gradient. velocity field is deduced from particle image velocimetry and flame structure visualized by means planar laser induced florescence OH radical. changes that nearly non-premixed to as gradient varied. curvature increases linearly over range tested. strain component stretch at leading edge equals critical gradient; further increase beyond this value shows progressively dominates component. propagation (global speed) reduction total until value, below which it decreases even though reduces further. local speed peaks same global speed, This explained balance between availability sufficient temperature excess reactants branches, lead heat contribution branch edge. For close extreme, measures less than along branches due sharp flow divergence upstream. towards diverges gradually; for such maximum changeover occurs corresponding peak velocity.