抄録
In the present paper, soot formation process was studied in pyrolysis of iso-octane added hydrogen highly diluted with argon in the temperature range of 1800-2600 K and in the pressure of 1.2 ± 0.1 MPa behind a reflected shock wave. As a test gas, 1% iso-C8H18 + 0-1% H2 diluted with Ar was used. Soot formation process was characterized by induction time and soot volume fraction, which was measured from laser light extinction measurement. In addition, time history of soot particle temperature was calculated based on spectral dependence of monochromatic emissive power from thermal radiation from the soot particles. The experimental results show that soot formation has bell-shaped temperature dependence exhibiting maximum at 2000 K with and without hydrogen addition. Adding hydrogen to iso-octane decreases soot volume fraction clearly for an initial ambient temperature T5 = 1800 K. Additionally, hydrogen addition prolongs induction time for T5 = 1800 K and 2000 K. Soot particle temperature TP is higher than T5 by about 200-400 K except for around 1800 K in the case of hydrogen addition. Consequently, soot formation is obviously suppressed for T5 = 1800 K, while no significant effects of hydrogen addition can be seen for T5 = 2000 K and 2500 K.
