When it comes to quality and efficiency, droplet diameters have a substantial impact on paint application processes. To determine droplet diameter distributions, Malvern-type laser diffraction and phase Doppler anemometry are common techniques. This has changed since 2014, as SpraySpy-type time-shift instruments became available. In this study, an industrial spray-painting atomization process using a rotary bell atomizer and an automotive clearcoat paint will be individually characterized using laser diffraction and time-shift measurements. Atomizer rotational speed and paint flow rate are varied in the experiments, while the remaining parameters are kept constant. The commonly used measurement setups are adapted and their respective outputs are converted to allow for a direct comparison. Analyzing the volumetric and number distributions of single measurements, it turns out that the laser diffraction device measures far more fine droplets than the time-shift instrument. The measurements of the latter indicate the presence of a considerable volume fraction in droplets larger than 100 mu;m, which has not been pointed out before. Analyzing the measurements of variations in atomizer rotational speed and paint flow rate, the laser diffraction device shows notably smaller droplet diameters, and its metrics are more strongly influenced by changes in atomizer rotational speed than those of the time-shift instrument, which is more sensitive to changes in paint flow rate with some metrics. Concerning the differences in absolute values, biases influencing the measurements are being discussed. For the time-shift instrument, a procedure to correct the biased measurements is introduced.

中文翻译：

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基于激光衍射和时移技术的工业旋转式钟形喷漆雾化过程的比较研究

在质量和效率方面，墨滴直径对涂料的涂覆工艺有很大影响。为了确定液滴直径分布，Malvern型激光衍射和相位多普勒风速仪是常用技术。自2014年以来，随着SpraySpy型时移仪器的问世，这种情况发生了变化。在这项研究中，将使用激光衍射和时移测量分别表征使用旋转钟形雾化器和汽车透明涂料的工业喷涂雾化过程。在实验中改变雾化器的旋转速度和涂料流量，同时保持其余参数不变。可以调整常用的测量设置，并转换它们各自的输出以进行直接比较。通过分析单次测量的体积和数量分布，可以发现激光衍射仪测量的细小液滴比时移仪器要多得多。后者的测量表明在大于100μm的液滴中存在相当大的体积分数，这之前没有指出。通过分析雾化器转速和涂料流量变化的测量结果，该激光衍射装置显示出明显更小的液滴直径，并且与时移仪器相比，其尺寸受雾化器转速变化的影响更大。某些指标来改变涂料的流速。关于绝对值的差异，正在讨论影响测量的偏差。对于时移仪器，