Ultra-high injection pressure and reduction of nozzle hole diameter are the development direction of future diesel engines. In this report, spray characteristics under evaporating condition are described. The results demonstrate that the increase in ambient temperature causes the spray near the nozzle to become wider. As the distance to the nozzle increases, the width of the spray tail near the nozzle tip slowly increases or remains basically unchanged. Under the evaporating condition, the spray head expands and assumes the shape of a mushroom head at the initial stage of injection. The spray of the micro-hole injector may be deflected to form a larger spray head under ultra-high injection pressure. Spray-tip penetration of injectors with different hole diameters is similar at the initial stage of injection. However, the increase in ambient temperature significantly reduces the time of similarity. The spray cone angle of micro-hole injectors under the evaporating condition is larger than that under the nonevaporating condition. But the cone angle of a large-hole injector under the nonevaporating condition is larger than that under the evaporating condition. Increases in ambient temperature only slightly affect the spray angle under different conditions. The spray evaporation results in a clear upward trend in the spray angle under 100 MPa conditions. However, under 300 MPa conditions, the spray angle does not increase because of the higher velocity. The spray evaporation effect of the micro-hole injector under a 300 MPa condition per unit mass is most favorable. The liquid length of the spray increases with the increase in the hole diameter, and a linear relationship exists between the liquid length and hole diameter of the injector. The liquid length of the spray is less affected by the injection pressure. Dos Santos' and Higgins's models can better predict the liquid length under different conditions.

中文翻译：

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超高压喷射压力蒸发喷射特性下微孔多孔喷射器的柴油喷射

超高喷射压力和减小喷嘴孔径是未来柴油机的发展方向。在这份报告中，描述了蒸发条件下的喷雾特性。结果表明，环境温度的升高导致喷嘴附近的喷雾变宽。随着距喷嘴距离的增加，喷嘴尖端附近的喷尾宽度缓慢增加或基本保持不变。在蒸发条件下，喷头在喷射的初始阶段膨胀并呈现蘑菇头的形状。微孔喷射器的喷射可以在超高喷射压力下偏转形成更大的喷头。不同孔径的喷油器在喷油初期的喷头穿透度是相似的。然而，环境温度的升高显着减少了相似时间。微孔喷射器在蒸发条件下的喷射锥角大于非蒸发条件下的喷射锥角。但大孔喷油器在非蒸发条件下的锥角大于蒸发条件下的锥角。在不同条件下，环境温度的升高对喷雾角度的影响很小。在 100 MPa 条件下，喷雾蒸发导致喷雾角度有明显的上升趋势。然而，在 300 MPa 条件下，喷射角不会因为更高的速度而增加。微孔喷射器在单位质量300 MPa条件下的喷雾蒸发效果最好。喷雾的液体长度随着孔径的增加而增加，喷油器的液体长度与孔径呈线性关系。喷雾的液体长度受注射压力的影响较小。Dos Santos 和 Higgins 的模型可以更好地预测不同条件下的液体长度。