層流予混合気におけるレーザ着火過程の高時間分解光学計測(熱工学,内燃機関,動力など)

概要

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This paper describes laser ignition process in a laminar premixed mixture of propane and air. The plasma was generated by focusing a second harmonic and several-nanosecond pulse emitted from a Q-switched Nd: YAG laser. Minimum ignition energy (MIE) was measured in different equivalence ratio. The growth process in the plasma and the hot kernel (flame kernel) around the MIE were observed using high-speed schlieren photography and a multi-fiber coupled to an ICCD spectrometer. The kernel size, the kernel expansion velocity and the emission spectrum history form the plasma and the kernel were determined under the ignition case and misfire case. Further, temperature of the plasma and the kernel were determined from the CN molecular spectra by comparing experimental and simulated (LIFBASE) spectra. The main results of this study are as follows: (1) In laser ignition method, combustion reaction begins through the cooling process in which the ion recombines to the atom, furthermore the atom recombines to the molecular after breakdown. (2) By analyzing the CH emission intensity history, it was considered that combustion reaction occurs confirmed about 100μs after laser pulse. (3) The temperature of the plasma and the kernel decrease with time and there were almost no difference between fire and misfire. (4) The minimum ignition energy is the smallest near the stoichiometric mixture.
一般社団法人日本機械学会の論文
2008-07-25