Nozzle hole diameter and injection pressure have a significant effect on diesel spray combustion and emission characteristics. The current work presents an experimental and computational study of diesel spray under nonevaporating and evaporating spray conditions, considering the effects of hole diameter and rail pressure. Three single-hole injectors with hole diameters of 0.101 mm, 0.122 mm, and 0.133 mm are studied with 120 MPa injection pressure. However, the 0.122 mm hole diameter injector is further tested with 100 MPa and 140 MPa injection pressures. The diffused backlight illumination method is applied in the nonevaporating diesel spray experiment, whereas the laser absorption scattering technique is implemented in the evaporating spray condition to measure the mixture concentration and visualize the vapor phase. Also, a computational fluid dynamics (CFD) simulation is performed, and results are validated against the experimental data. Since the rate of injection profile plays a decisive role in the CFD calculation, injection rates with various low-pass filters are carefully measured using the Zeuch method. The Butterworth low-pass filter with a cut-off frequency of 5 kHz is chosen based on a similar start of injection with the high-speed video camera start-of-injection frame. In the nonevaporating spray condition, a 0.133 mm hole diameter injector and 140 MPa injection pressure show higher injection rates, thus producing longer spray tip penetration among their counterparts. Likewise, in the evaporating spray condition, a 0.101 mm hole diameter injector and 140 MPa injection pressure exhibit a longer vapor spray tip penetration and higher evaporation ratio. The CFD simulation predicts the experimental spray tip penetration accurately; however, the spray cone angle and the spray angle are underpredicted in the nonevaporating spray condition. Moreover, in the evaporating condition, the computational study shows a disagreement with the experimental vapor penetration length, while showing a good agreement with the evaporation ratio.

中文翻译：

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非蒸发和蒸发条件下柴油机喷雾的实验与计算研究-喷嘴孔径和注射压力的影响。

喷嘴孔直径和喷射压力对柴油机喷雾燃烧和排放特性有重要影响。考虑到孔径和轨道压力的影响，当前的工作提出了在非蒸发和蒸发喷雾条件下柴油喷雾的实验和计算研究。在120 MPa的注射压力下，研究了三种孔径分别为0.101 mm，0.122 mm和0.133 mm的单孔进样器。但是，将在100 MPa和140 MPa的注射压力下对0.122 mm孔径的注射器进行进一步测试。在非蒸发柴油喷雾实验中采用了漫射背光照明方法，而在蒸发喷雾条件下实施了激光吸收散射技术以测量混合物浓度并可视化气相。也，进行计算流体动力学（CFD）仿真，并根据实验数据验证结果。由于进样速度在CFD计算中起着决定性的作用，因此使用Zeuch方法仔细测量各种低通滤波器的进样速度。基于与高速摄像机注入起始帧相似的注入起始时间，选择了截止频率为5 kHz的巴特沃斯低通滤波器。在非蒸发喷涂条件下，孔径为0.133 mm的进样器和140 MPa的注入压力显示出更高的注入速率，因此在其对应部件之间产生了更长的喷嘴穿透力。同样，在蒸发喷涂条件下，孔径为0.101 mm的进样器和140 MPa的注入压力表现出更长的蒸汽喷涂尖端穿透力和更高的蒸发比。CFD仿真可准确预测实验喷嘴的穿透力；然而，在非蒸发喷雾条件下，喷雾锥角和喷雾角被低估了。此外，在蒸发条件下，计算研究表明与实验蒸汽渗透长度不一致，而与蒸发比显示出很好的一致性。