In the last few decades, stringent emission norms have forced the engine research community and OEMs to develop new spark ignition engine technologies, such as variable valve lift, turbocharging, and direct injection spark ignition (DISI) engines. For further development, greater control of parameters such as in-cylinder air motion, spray characteristics, injection, and ignition events are required. Spray characterisations are crucial for understanding the mixing phenomena in heated and pressurised ambient conditions. Spray pattern, fuel injection pressure (FIP), rate shape, and thermodynamic conditions of the combustion chamber play a vital role in the mixture preparation. The present study uses Mie-Scattering techniques to examine spray structures of fuels like methanol and ethanol, which are of great interest to DISI engines. Three different temperatures of 50, 100, and 200℃ and two ambient pressures, 4 bar and 8 bar, were considered to simulate typical engine-like conditions. It was observed that the initial chamber conditions greatly influenced the spray structure. Spray collapse was lesser for alcohol than gasoline. Spray penetration length increased with an increasing FIP.

中文翻译：

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DISI 发动机条件下汽油、甲醇和乙醇的宏观喷雾特性

在过去的几十年里，严格的排放标准迫使发动机研究界和原始设备制造商开发新的火花点火发动机技术，例如可变气门升程、涡轮增压和直喷火花点火（DISI）发动机。为了进一步开发，需要对缸内空气运动、喷雾特性、喷射和点火事件等参数进行更好的控制。喷雾特性对于理解加热和加压环境条件下的混合现象至关重要。喷雾形式、燃油喷射压力 (FIP)、速率形状和燃烧室的热力学条件在混合物制备中起着至关重要的作用。本研究使用米氏散射技术来检查甲醇和乙醇等燃料的喷雾结构，DISI 发动机对这些燃料非常感兴趣。考虑了 50、100 和 200℃ 三种不同的温度以及 4 bar 和 8 bar 两种环境压力来模拟典型的类似发动机的条件。据观察，初始室条件极大地影响了喷雾结构。酒精的喷雾塌陷比汽油的要小。喷雾穿透长度随着 FIP 的增加而增加。