Flame kernel growth study of spark ignited hydrogen air premixed combustion at engine conditions

Abstract

In this study, the spark ignition of H2-air mixture was investigated experimentally in a constant volume combustion chamber and numerically at initial pressure of 3 bar. The relative air fuel ratio was varied from 0.8 to 1.4 and initial temperature was varied from 303 to 423 K. The flame propagation velocity and pressure rise were recorded. The flame kernel images were processed to get the stretched flame velocity of the mixture. Further the stretched flame velocity was estimated using the unstretched flame velocity and calculating the stretch rate. It was found that the combustion chamber pressure rise is dependent negatively on the initial temperature. With increasing initial temperature, the peak pressure decreases. The stretched and unstretched flame velocities increase with initial temperature and decrease when the mixture becomes leaner due to the change in concentration of free radicals in the combustion chamber.