Impact of Nitrogen and Angle of Nozzle on the Stability of Premixed Counter Flame
LPG/air flames in axi-symmetric opposed nozzle burners were experimentally investigated for different flow
velocities, nozzle geometries, and N2. The variety of experimental techniques employed allowed considering the issue from
various perspectives, providing information on the interaction between the fluid dynamic processes and chemical reactions
taking place in the burner: The fluid dynamic instabilities can trigger the complete flame extinction, where a flame re-ignition
would be expected considering the stability diagrams. For detailed investigations of processes and phenomena in the
premixed counter flow, it is sometimes necessary to apply more than just one flow visualization technique, since each method
has its own characteristics of strengths and weaknesses. In the present study, Schlieren technique was used to analyze the
effect of nozzles angle (30⁰, 45⁰, and 60⁰) and nitrogen on the flame stability. Significant results were obtained in the area of
flame propagation. Limits of stability in the counter flow (blow-off flame, double flame, disc flame and distortion flame)
depend basically on the shape of nozzles and velocity of fuel and air. Use of N2 leads to a decrease in the convective heat loss
as the strain is increased. Increasing the strain will also reduce the flame width by pushing the flame closer to the stagnation
surface to keep the balance between the burning velocity and the flow velocity.
Index Terms - Premixed Counter Flame, Angle of Nozzle, N2, Stability.