In response to the problem that the flame temperature field and carbon soot concentration field of diesel-ignited high-pressure direct-injection natural gas are still unclear.On a constant-volume combustion bomb platform,a high-pressure direct injection(HPDI)natural gas coaxial injector was used to study the distribution characteris-tics of flame temperature and soot KL value after HPDI natural gas combustion under different diesel/gas injection pressures and diesel/gas injection intervals using a high-speed color camera and the dual-color method.This study provides a basic reference for the fuel injection strategy of HPDI natural gas engines and for related research on re-ducing soot formation.The results show that the flame average temperature and soot average KL value decrease with the increase in the diesel/gas injection pressure after high-pressure natural gas is ignited.Thus,the diesel/gas in-jection pressure should be increased to reduce the soot KL value.When the diesel/gas injection interval is 0.8 ms,the average temperature of the high-pressure natural gas jet flame is the highest at up to 2 318 K.When the injec-tion interval is 0.4 ms,the average temperature of the flame is the lowest at 2 148 K at most.At the same moment,the average KL value of soot at a 0.8 ms diesel/air injection interval is increased by 112.8%at most compared with that at 0.4 ms and increased by 49.02%at most compared with that at a 1.2 ms injection interval.The experimen-tal results show that,to reduce the soot formation level during high-pressure directly injected natural gas combus-tion,the injection interval should be set before the end of diesel injection.
关键词
高压直喷/双色法/定容弹/天然气/碳烟/火焰温度/喷射压力/喷射间隔
Key words
high-pressure direct injection/double-color method/constant-volume bomb/natural gas/soot/flame temperature/injection pressure/injection interval
维普
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