Experimental study of liquid droplets impact on powder surface: The application of effective dimensionless parameters in analysis

Spreading dynamics of liquid droplets impacting onto powder bed are experimentally studied using high-speed photography. Dimensionless numbers— We , Re , the modified We * and Re ∗ corrected by substrate deformation—are used to analyze the impact behaviors of droplets. The spreading time and the maximum spreading factor are further analyzed. The spreading time is accurately described by a universal scaling law that is obtained from the modified dimensionless time vs. the effective Weber number ( We ∗ ), and the maximum spreading factor is found to follow the modified classic scaling law β max = f ( We * , Re * ).