An Experimental Study of the Effect of Partial Premixing Level on the Interaction between the Flame Kernel and Flow Field

Flame kernels in spark-ignited combustion systems dominate the flame propagation and combustion stability, performance and emissions. The aim of the present work is to investigate the flow field associated with flame kernel propagation history in partial premixing natural gas turbulent flames. The main parameters under investigation are the degree of partial premixing and jet velocity. Three different degrees of partial premixing and five values of jet velocity between10 and 20 m/s have been selected for the present work at an equivalence ratio of 2. The mean flow field and turbulence intensity are measured using two-dimensional Planar Imaging Velocimetry (PIV). A pulsed Nd: YAG laser is used for flame ignition. The turbulent flow field is captured after the ignition at several time intervals between, 150, and 2500 µs after ignition. The results show that the flame kernel does not show any significant effect on the scale of mean flow field. On the other hand, the flame kernel increases the global turbulence intensity in flames in comparison with the isothermal cases. The flame kernel propagation is associated with a steep increase in the centerline turbulence intensity of the jet flow. An increase in the degree of partial premixing and/or the jet velocity increases the centerline turbulence intensity accompanying th