Combustion characteristics and flame-kernel development of a laser ignited hydrogen-air mixture in a constant volume combustion chamber

摘要

Laser ignition of hydrogen-air mixture was carried out in a constant volume combustion chamber (CVCC) at 10 bar initial chamber filling pressure and 373 K chamber temperature. A Q-switched Nd:YAG laser at 1064 nm with a pulse duration of 6-9 ns was used for plasma generation and ignition of combustible hydrogen-air mixture. Pressure-time history of different hydrogen-air mixtures was measured in the CVCC and flammability limits of hydrogen-air mixture were measured. Flame kernel development was investigated for different air-fuel mixtures using Shawdowgraphy and flame propagation distances were calculated. Minimum ignition energy was measured for hydrogen-air mixtures of different air-fuel ratios and effect laser pulse energy on pressure-time history in the CVCC was experimentally measured. Upon increasing the laser pulse energy, time taken to attain peak cylinder pressure reduced which resulted in faster combustion in hydrogen-air mixtures however the peak cylinder pressure remained similar.