\r刘昌文¹，刘宗宽¹，刘 博²，周 磊¹，卫海桥\r¹\r
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AuthorsHTML:\r刘昌文¹，刘宗宽¹，刘 博²，周 磊¹，卫海桥\r¹\r
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AuthorsListE:\rLiu Changwen¹，Liu Zongkuan¹，Liu Bo ²，Zhou Lei¹，Wei Haiqiao\r¹\r
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AuthorsHTMLE:\rLiu Changwen¹，Liu Zongkuan¹，Liu Bo ²，Zhou Lei¹，Wei Haiqiao\r¹\r
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Unit:\r\r1. 天津大学内燃机燃烧学国家重点实验室，天津 300072；\r
\r\r2. 中船动力研究院有限公司，上海 201206\r
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Unit_EngLish:\r1. State Key Laboratory of Engines，Tianjin University，Tianjin 300072，China；
2. China Shipbuilding Power Engineering Institute Co.，Ltd.，Shanghai 201206，China\r
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Abstract_Chinese:\r\r为提高天然气\r/\r柴油双燃料船用低速发动机低负荷时的燃烧稳定性、避免高负荷时爆震发生，采用三维数值模拟的方法，研究了实际双燃料发动机中引燃油喷射时刻对缸内混合气的着火\r/\r燃烧特性及缸内压力振荡的影响．结果表明：甲烷当量比为\r0.38\r的工况，引燃油喷射时刻的推迟会造成缸内甲烷\r/\r空气混合气的着火时刻和燃烧相位推迟，缸内压力减小且爆压相位滞后；当喷射时刻推迟至\r2.\r0\r°\rCA\r BTDC\r时，缸内压力峰值低于\r10MPa\r，说明燃烧严重恶化，甚至出现失火现象．甲烷当量比为\r0.50\r的工况，引燃油喷射时刻的推迟使缸内压力振荡幅度增大且振荡发生的时刻推迟，当喷油时刻推迟至\r2.\r0\r°\rCA\r BTDC\r时，甲烷\r/\r空气混合气在引燃油喷射之前发生自燃；此外，喷油时刻的推迟会导致火焰发展速度加快且火焰前端燃烧更为剧烈，易在靠近壁面的狭小空间内产生压力振荡．\r\r
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Abstract_English:\r\rFor improving combustion stability under low engine load and avoiding knock occurrence under high engine load in natural gas/diesel dual fuel engines\r，\ra three-dimensional numerical study was performed herein to investigate the influences of pilot fuel injection timing on ignition/combustion characteristics and in-cylinder pressure oscillation under engine-like conditions\r．\rResults showed that both the onset of CH₄/air mixture ignition and in-cylinder combustion phasing retarded with the postponement of pilot fuel injection timing in cases with a 0.38 CH₄ equivalence ratio\r，\rthereby decreasing in-cylinder pressure and delaying peak pressure phasing\r．\rAs the pilot fuel injection timing was delayed to 2.0°CA before the top dead center\r(\rBTDC\r)\r，\rin-cylinder peak pressure was observed to be below 10MPa\r，\rindicating combustion deterioration\r．\rFurthermore\r，\ra misfire may follow\r．\rIn cases with a 0.50 CH₄ equivalence ratio\r，\rthe pressure oscillation phase was delayed as the prolongation of pilot fuel injection timing\r，\rand the amplitude of pressure oscillation increased\r．\rAuto-ignition of the CH₄/air mixture appeared in the pre-chamber before pilot fuel injection in the case with a pilot fuel injection timing of 2.0°CA BTDC\r．\rFurthermore\r，\rdelaying the start of injection\r(\rSOI\r)\raccelerated flame development and enhanced combustion intensity on the flame surface\r，\rcausing pressure oscillation in a narrow space near the cylinder wall\r．\r\r
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Keyword_Chinese:双燃料；引燃油；喷射时刻；着火特性；压力振荡\r

Keywords_English:dual fuel；pilot fuel；injection timing；ignition characteristic；pressure oscillation\r


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