Abstract Spray-wall impingement has been proved unavoidable in direct-injection spark-ignition (DISI) engines, which affects the fuel-air formation as well as combustion and exhaust emissions, making it difficult to meet the regulation of particle number (PN) in the future standards. In this study, the characteristics of fuel adhesion injected by a mini-sac gasoline injector with a single hole were investigated in a constant high-pressure chamber. The fuel spray and adhesion were measured via Mie scattering and refractive index matching (RIM) methods, respectively. The effect of injection pressure on the spray-wall interaction under room and high temperature condition were tested. The results showed that under room temperature, the injection pressure promotes better atomization, resulting in longer spray tip penetration, larger impinging spray height, and more fuel adhesion on the wall. However, when evaporation occurs, higher injection pressure favors the fuel evaporation due to the small droplets size, leading to shorter spray tip penetration, smaller impinging spray height, and less fuel adhesion on the wall. Moreover, under non-evaporation condition, high injection pressure has less effect on the uniformity of the fuel adhesion on the wall, while under evaporation condition, it improves the uniformity of the fuel adhesion. Owing to the different mechanisms of the fuel adhesion formation in the primary impingement (Region I) and secondary impingement (Region II) regions, injection pressure has more influence on the fuel adhesion in Region I, especially under evaporation condition.

中文翻译：

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非蒸发和蒸发条件下的燃油粘附特性：第 1 部分-喷射压力的影响

摘要 喷射壁撞击已被证明在直喷火花点火（DISI）发动机中是不可避免的，它影响燃料空气形成以及燃烧和废气排放，使其难以满足颗粒数（PN）的规定。未来的标准。在这项研究中，在恒定高压室中研究了单孔微型囊式汽油喷射器喷射的燃油粘附特性。燃料喷雾和附着力分别通过米氏散射和折射率匹配 (RIM) 方法测量。测试了注射压力对室温和高温条件下喷射壁相互作用的影响。结果表明，在室温下，注射压力促进了更好的雾化，导致更长的喷嘴穿透，更大的撞击喷雾高度，更多的燃料附着在壁上。然而，当蒸发发生时，由于液滴尺寸小，较高的喷射压力有利于燃料蒸发，导致更短的喷嘴穿透、更小的撞击喷雾高度和更少的燃料粘附在壁上。而且，在非蒸发条件下，高喷射压力对壁面燃油附着的均匀性影响较小，而在蒸发条件下，提高了燃油附着的均匀性。由于一次冲击（I 区）和二次冲击（II 区）区域燃油粘附形成的机制不同，喷射压力对 I 区燃油粘附的影响更大，尤其是在蒸发条件下。由于小液滴尺寸，较高的喷射压力有利于燃料蒸发，从而导致更短的喷嘴穿透、更小的撞击喷雾高度和更少的燃料粘附在壁上。而且，在非蒸发条件下，高喷射压力对壁面燃油附着的均匀性影响较小，而在蒸发条件下，提高了燃油附着的均匀性。由于一次冲击（I 区）和二次冲击（II 区）区域燃油粘附形成的机制不同，喷射压力对 I 区燃油粘附的影响更大，尤其是在蒸发条件下。由于小液滴尺寸，较高的喷射压力有利于燃料蒸发，从而导致更短的喷嘴穿透、更小的撞击喷雾高度和更少的燃料粘附在壁上。而且，在非蒸发条件下，高喷射压力对壁面燃油附着的均匀性影响较小，而在蒸发条件下，提高了燃油附着的均匀性。由于一次冲击（I 区）和二次冲击（II 区）区域燃油粘附形成的机制不同，喷射压力对 I 区燃油粘附的影响更大，尤其是在蒸发条件下。和更少的燃料粘附在墙上。而且，在非蒸发条件下，高喷射压力对壁面燃油附着的均匀性影响较小，而在蒸发条件下，提高了燃油附着的均匀性。由于一次冲击（I 区）和二次冲击（II 区）区域燃油粘附形成的机制不同，喷射压力对 I 区燃油粘附的影响更大，尤其是在蒸发条件下。和更少的燃料粘附在墙上。而且，在非蒸发条件下，高喷射压力对壁面燃油附着的均匀性影响较小，而在蒸发条件下，提高了燃油附着的均匀性。由于一次冲击（I 区）和二次冲击（II 区）区域燃油粘附形成的机制不同，喷射压力对 I 区燃油粘附的影响更大，尤其是在蒸发条件下。