Parametric study of a laser ignited hydrogen–air mixture in a constant volume combustion chamber

Experiments were carried out in a constant volume combustion chamber (CVCC) to investigate flame kernel development and flame speed of hydrogen–air mixtures having different fuel–air ratios. A Q-switched Nd: YAG laser with 1064 nm wavelength and pulse duration of 6–9 ns was used for ignition by generating laser induced plasma inside the CVCC. In this study, laser induced ignition of hydrogen–air mixtures was investigated using different initial chamber filling pressures (P = 2.5 bar–10 bar) at different initial temperatures (373 K–523 K). A variable optical setup with converging lenses having different focal lengths (f = 100–250 mm) were used to position the plasma at various locations inside the CVCC. A high speed camera recorded the flame kernel development and a piezoelectric pressure transducer recorded the pressure–time history for all the experiments. The main objective of this study was to determine the dependence of combustion properties of laser ignited hydrogen–air mixtures on lasers, optical configurations and initial conditions prevailing in the CVCC.