【摘要】 通过可视化定容燃烧弹试验台,采用纹影法研究了强化混合条件对乙醇柴油(E 20)和柴油喷雾混合特性的影响,喷油压力为50~200,MPa,燃油温度为343~423,K.试验表明:随喷油压力提高,喷雾锥角略有减小,但喷雾贯穿距和喷雾体积显著增大,喷雾的油气混合速率大幅提高;随燃油温度增加,喷雾锥角、喷雾贯穿距和喷雾体积变化不大,喷雾混合速率变化不明显.尽管乙醇的挥发性高于柴油,但添加乙醇对柴油喷雾的贯穿距和喷雾锥角影响不大.E 20喷雾贯穿距略小于柴油,喷雾锥角比柴油的约大5%,卷吸的空气体积比柴油稍大,燃空当量比小于柴油,形成稀混合气所需的时间更短.降低氧体积分数将使燃空当量比增大.提高喷油压力和掺混乙醇是加快柴油喷雾稀混合气形成速率的可行方法.更多还原

【Abstract】 Spray and mixing characteristics of ethanol-diesel blend(E,20)and diesel were investigated under intensified mixing conditions in an optical accessible constant volume combustion bomb using schlieren method. Injection pressure and fuel temperature vary from 50—200,MPa,and 343—423,K respectively. Results show that,with the increase of injection pressure,spray cone angle decreases slightly,while spray tip penetration,spray volume and fuel air mixing rate increase significantly. Fuel temperature has negligible effect on these parameters. Ethanol addition has small influence on diesel spray penetration and cone angle despite its outstanding volatility. Compared with diesel,spray penetration of E 20 is slightly shorter,spray cone angle of E 20 and entrained air volume are slightly larger,and fuelair equivalence ratio is decreased. It takes shorter time to form the desirable lean mixture for E 20 spray compared with that of diesel spray. Lower oxygen concentration results in higher fuel-air equivalence ratio. Elevating injection pressure and addition of ethanol are the effective methods to speed up lean diesel spray mixture formation process.更多还原