二冲程点燃式直喷重油发动机混合气形成CFD仿真研究
发布时间：2018-09-08 12:27
【摘要】：重油燃料蒸发性差,二冲程发动机压缩终了时缸内气体滚流速度较高,喷油时刻对缸内混合气浓度分布影响很大,从而影响发动机燃烧的稳定性。为保证标定试验时发动机的安全,本文通过CFD仿真研究二冲程点燃式重油发动机缸内混合气形成过程,得出以下结论:发动机转速为40000rpm,油门开度为18°时,喷油结束角为40°CA BTDC时,火花塞电极周围混合气浓度较稀,解释了过去在发动机标定试验过程中,该工况以及该喷油结束角的情况下,发动机出现失火现象的原因。油门开度为18°,转速为4000rpm和4500rpm时,其使燃烧稳定的适宜的喷油结束角的范围分别在80°~120°CA BTDC附近和100°~140°CA BTDC附近。转速为4000rpm,油门开度分别为18°,32°和44°,使燃烧稳定的适宜的喷油结束角的范围分别在80°~120°CA BTDC附近,100°~160°CA BTDC附近和120°~160°CA BTDC附近,说明随着发动机负荷加大,使燃烧稳定的适宜的喷油结束角的范围有提前的趋势。发动机转速为4000rpm,在小负荷的工况下(18°),扫气侧火花塞主要起点火作用,而在中等负荷(32°)和大负荷(44°)的工况下,排气侧火花塞起主要点火作用,其验证了使用双火花塞的必要性。本文最后在二冲程点燃式重油发动机上进行试验,结果表明:油门开度为18°,转速分别为4000rpm和4500rpm时,其最大扭矩所对应的喷油结束角分别为100°CA BTDC和130°CA BTDC;发动机转速为4000rpm,油门开度为32°和44°时,其最大扭矩所对应的喷油结束角分别为140°CA BTDC和150°CA BTDC。其最大扭矩对应的喷油结束角处于仿真结果的范围内。验证了缸内混合气形成的CFD仿真结果的一致性,从而为发动机台架标定试验喷油策略提供了一定的指导意义。
[Abstract]:The vaporization of heavy oil fuel is poor, the gas rolling velocity in cylinder is higher at the end of compression of two-stroke engine, and the fuel injection time has a great influence on the mixture concentration distribution in the cylinder, thus affecting the combustion stability of the engine. In order to ensure the safety of the engine during the calibration test, the formation process of the mixture in the cylinder of the two-stroke ignition heavy oil engine is studied by CFD simulation. The following conclusions are obtained: when the engine speed is 40000rpm, the throttle opening is 18 掳, the fuel injection end angle is 40 掳CA BTDC. The concentration of mixture around the spark plug electrode is relatively thin, which explains the cause of engine misfire under the condition of this condition and the end angle of the fuel injection during the past engine calibration test. When the throttle opening is 18 掳and the rotational speed is 4000rpm and 4500rpm, the suitable range of fuel injection end angle for combustion stability is about 80 掳CA BTDC and 140 掳CA BTDC, respectively. The rotational speed is 4000rpm and the throttle opening is 18 掳/ 32 掳and 44 掳, respectively. The suitable end angle of fuel injection for stable combustion is in the range of 80 掳~ 120 掳CA BTDC and 120 掳~ 160 掳CA BTDC and 160 掳CA BTDC respectively, which indicates that the engine load increases with the increase of engine load. The range of suitable end angles for fuel injection to stabilize combustion tends to advance. The engine speed is 4000rpm, under the condition of small load (18 掳), the scavenging side spark plug mainly ignites, but under the condition of medium load (32 掳) and high load (44 掳), the exhaust side spark plug plays the main role of ignition, which verifies the necessity of using double spark plug. In the end, the test is carried out on a two-stroke ignition heavy oil engine. The results show that when the throttle opening is 18 掳and the rotational speed is 4000rpm and 4500rpm, respectively, The fuel injection end angle corresponding to the maximum torque is 100 掳CA BTDC and 130 掳CA BTDC; engine speed is 4000rpm, and when the throttle opening is 32 掳and 44 掳, the fuel injection end angle corresponding to the maximum torque is 140 掳CA BTDC and 150 掳CA BTDC., respectively. The fuel injection end angle corresponding to its maximum torque is within the range of simulation results. The consistency of CFD simulation results of in-cylinder mixture formation is verified, which provides some guidance for the injection strategy of engine bench calibration test.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK401
本文编号：2230517
[Abstract]:The vaporization of heavy oil fuel is poor, the gas rolling velocity in cylinder is higher at the end of compression of two-stroke engine, and the fuel injection time has a great influence on the mixture concentration distribution in the cylinder, thus affecting the combustion stability of the engine. In order to ensure the safety of the engine during the calibration test, the formation process of the mixture in the cylinder of the two-stroke ignition heavy oil engine is studied by CFD simulation. The following conclusions are obtained: when the engine speed is 40000rpm, the throttle opening is 18 掳, the fuel injection end angle is 40 掳CA BTDC. The concentration of mixture around the spark plug electrode is relatively thin, which explains the cause of engine misfire under the condition of this condition and the end angle of the fuel injection during the past engine calibration test. When the throttle opening is 18 掳and the rotational speed is 4000rpm and 4500rpm, the suitable range of fuel injection end angle for combustion stability is about 80 掳CA BTDC and 140 掳CA BTDC, respectively. The rotational speed is 4000rpm and the throttle opening is 18 掳/ 32 掳and 44 掳, respectively. The suitable end angle of fuel injection for stable combustion is in the range of 80 掳~ 120 掳CA BTDC and 120 掳~ 160 掳CA BTDC and 160 掳CA BTDC respectively, which indicates that the engine load increases with the increase of engine load. The range of suitable end angles for fuel injection to stabilize combustion tends to advance. The engine speed is 4000rpm, under the condition of small load (18 掳), the scavenging side spark plug mainly ignites, but under the condition of medium load (32 掳) and high load (44 掳), the exhaust side spark plug plays the main role of ignition, which verifies the necessity of using double spark plug. In the end, the test is carried out on a two-stroke ignition heavy oil engine. The results show that when the throttle opening is 18 掳and the rotational speed is 4000rpm and 4500rpm, respectively, The fuel injection end angle corresponding to the maximum torque is 100 掳CA BTDC and 130 掳CA BTDC; engine speed is 4000rpm, and when the throttle opening is 32 掳and 44 掳, the fuel injection end angle corresponding to the maximum torque is 140 掳CA BTDC and 150 掳CA BTDC., respectively. The fuel injection end angle corresponding to its maximum torque is within the range of simulation results. The consistency of CFD simulation results of in-cylinder mixture formation is verified, which provides some guidance for the injection strategy of engine bench calibration test.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK401
【引证文献】
相关期刊论文 前1条
1 牛燕华;魏民祥;吴伟建;季昊成;;二冲程缸内直喷发动机燃烧室设计[J];重庆理工大学学报(自然科学);2017年04期
，本文编号：2230517
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