An experimental study on promotion of burning velocity of powder-gas hybrid combustion in a stagnation-point flow

An experimental study was made on burning velocity in powder-gas hybrid combustion in order to investigate the determination factor to alter the burning velocity caused by the addition of power in the premixed gas. A burner system was newly developed to visualize the dynamic flame behavior originally stabilized in a stagnation point flow field. Using the system, the instantaneous burning velocity and burning area by powder loading were obtained and analyzed. It was found that the burning velocity and burning area varied substantially in accordance with the powder loading amount. Data analyses exhibited that a positive correlation was found between them, suggesting that wrinkling shall be a major cause to alter the burning velocity. To understand the mechanism of wrinkle formation, the change of the flow field ahead of the flame with powder loading was measured. It is suggested that the wrinkles could be attributed to the pyrolysis gases evolved in the preheating zone, which could both increase the local burning velocity by increasing the local equivalence ratio and change the flow field due to the divergence flow generated by each powder. Further study would be needed to confirm the suggested mechanism.