In transition region of turbulent jet diffusion flames, instantaneous ion current signals at various points were measured simultaneously using multiple probes and the schlieren photographs were taken. Vertical triple co-axial jet was used; inner tube for propane fuel, middle one for oxygen as a type of flame holder an outer one for air.
In the schlieren photographs, it was found that the visible flame is located away from the fuel jet boundary and due to the presence of flame, the mixing rate of air-fuel and the spreading rate of fuel are decreased.
The presence of time - delay in the ion current signal obtained by the vertically installed probes shows that the convection of the flow field has a significant effect on the ion current signal.
