Experimental Study on Combustion Characteristics of Methane-Hydrogen Mixed Fuel in Small Circular Nozzle (2) - Apparent Burning Velocity

To understand the combustion characteristics of methane-hydrogen mixed fuel, its flame was visualized using small nozzles with a diameter of 3 mm in a Bunsen burner. Schlieren images were obtained by changing the combustion conditions for the flame of low-hydrogen-fraction fuel, and the apparent burning velocity was calculated based on schlieren images using the area method. The conclusions obtained are as follows: The apparent combustion velocity increases with the hydrogen mole fraction, whereas it decreases as the equivalence ratio increases. This change trend according to equivalence ratio differs significantly from that of the general combustion velocity. Additionally, significantly different values are indicated between the two change trends. The change trend of the apparent combustion velocity differs from that of the general combustion velocity owing to the extremely small nozzle used. However, this phenomenon cannot be interpreted based on flame extension.