Experimental study on the Markstein length and laminar burning velocity of CH4/RP-3 mixture

Experimental studies were performed to investigate the effects of methane addition on the combustion characteristics of Chinese RP-3 kerosene/air mixture. Experiments were in a combustion vessel and the influences of methane addition on the flame propagation characteristic, Markstein length and laminar burning velocity of CH4/RP-3/air mixture at initial temperature of 420 K, initial pressure of 0.1 MPa, equivalence ratios of 0.8-1.3 and methane additions of 0.0-0.8 were investigated. Results show that with the increase of equivalence ratio, the flame front of RP-3/air mixture becomes unstable and a cellular flame structure is observed when the equivalence ratio increases to 1.3, but at the equivalence ratio of 1.3, the increased methane addition can make the flame front stable significantly. With the increase of equivalence ratio from 0.8 to 1.3, laminar burning velocities of CH4/RP-3/air mixture first increase and then decrease; the effect of methane addition on laminar burning velocity is not evident at the equivalence ratios of 0.9-1.1, but when the equivalence ratio is larger than 1.1, laminar burning velocities with methane addition of 0.8 are always the slowest. The Markstein length decreases with the increase of equivalence rati; at equivalence ratio of 0.8 the Markstein length decreases with the increase of methane addition, and with the increase of equivalence ratio the influence of methane addition on Markstein length becomes less significant and irregular.