内混式空气助力喷嘴喷雾水滴尺寸分布建模

获取喷嘴出口喷雾的水滴尺寸分布(DSD)和水滴平均直径(MVD)对地面结冰实验设施云雾参数计算与调试至关重要。采用相位多普勒干涉仪对内混式空气助力喷嘴开展了喷雾实验研究;采用最小二乘法确定了DSD经验函数参数,建立了喷嘴出口喷雾的DSD模型,探究了喷嘴动力参数(NDPs)对DSD的影响;校验了Wigg MVD估算公式及其修正形式,分析其在具体工程应用中的局限性,提出了基于NDPs的MVD估算公式。研究发现:修正Rosin-Rammler分布函数与实验数据更为吻合,可作为描述喷嘴出口喷雾DSD的模型;NDPs对DSD有明显影响,且气压的影响更为显著;基于NDPs的MVD估算公式能提供精度可接受的MVD预估值,且比Wigg MVD估算公式及其修正形式更易于工程应用。

Modeling droplet size distribution of spray for an internal-mixing air-assisted nozzle

Obtaining the droplet size distribution (DSD) and median volume diameter (MVD) is of key importance for the parameters prediction and calibration of simulated icing cloud in ground-based icing test facilities. The investigation involves the experimental measurement of spray generated by an internal-mixing air-assisted nozzle based on phase Doppler interferometer, the model establishment of DSD near the orifice of nozzle using the least square technique, the influence of nozzle dynamic parameters (NDPs) on DSD through varying the NDPs, and the establishment of a formula that express the relationship between NDPs and MVD. It is found that the modified Rosin-Rammler distribution function can better approximate the experimental data, therefore it could be modeled to describe the DSD of spray produced by tested nozzle. The NDPs have a significant influence on spray performance; however, the air pressure has a dominative effect on the droplet size of spray when holding equal increment on air and water pressure. The NDPs-based MVD prediction formula can provide acceptable prediction of MVD, and is more convenient in engineering application than Wigg MVD empirical formula and its modified formula.