高压直喷点燃式发动机燃用航空煤油掺混乙醇对燃烧性能优化的试验研究

为提高航空煤油在点燃式发动机中的燃烧热效率,改善发动机爆震及拓宽发动机负荷范围,以3号航空煤油(RP3)为基础燃料,以乙醇为辅助燃料,基于一台单缸水冷、压缩比可调、四冲程点燃式发动机结合高压共轨缸内直喷技术,开展了不同负荷、不同乙醇和航空煤油掺混比、不同喷射压力、不同喷射时刻下航空煤油燃烧特性的试验研究。结果表明,在压缩比为7的条件下,由于爆震的限制,发动机负荷仅能达到原机的72.0%。而乙醇具有较强的抑制爆震的能力,随着乙醇在航空煤油中掺混比例的增加,发动机负荷区间不断拓展,当乙醇的掺混比为10%时发动机可实现全负荷工作。继续增大乙醇的掺混比例,可进一步提升功率并降低油耗。为探究喷油时刻对动力性、经济性的影响,试验测定了5种喷油时刻对燃烧性能的影响。当喷油时刻为压缩上止点前300°时,发动机具有较好的动力性;当喷油时刻为上止点前360°时,发动机具有较好的经济性。

Experimental Study on the Optimization of Combustion Performance of a High-Pressure Direct Injection SI Engine Fueled with Aviation Kerosene Blended with Ethanol

In order to improve the combustion thermal efficiency of aviation kerosene in spark ignition engine, improve engine detonation and broaden engine load range. Based on RP3 as the basic fuel and ethanol as the auxiliary fuel, and a single cylinder wa-ter-cooled, adjustable compression ratio, four-stroke ignition engine combined with high pressure common rail in-cylinder direct injection technology, the combustion characteristics of aviation kerosene under different loads, ethanol/aviation kerosene blend-ing ratio, injection pressure and injection timing were studied. The results show that under the condition of compression ratio of 7, the engine load can only reach 72% of the original engine due to detonation limitation. With the increase of ethanol blending ratio in aviation kerosene, the engine load range expands continuously. When the ethanol blending ratio is 10%, the engine can work at full load. Increasing the blending ratio of ethanol can further increase power and reduce fuel consumption. In order to explore the influence of injection time on power and economy, the effects of five injection timings on combustion performance were tested. When the injection time was 300°BTDC, the engine had better power performance. When the injection time was 360°BTDC, the engine had better economy.