Impingement of NaCl solution droplets onto a rotational surface

In the present study, the impact process of droplets with different concentrations of NaCl onto a rotational surface was experimentally studied. The effects of rotational velocity and NaCl concentration on impact behaviors were carefully investigated. Various phenomena, including asymmetric spreading, round and sharp leading edges, finger formation, and secondary droplets, were observed. The results showed that, at the same rotational velocity, the decrease in the concentration of NaCl could increase the wetting area. In addition, at the same concentration of NaCl, the increase in rotational velocity could increase the wetting area and the number of fingers. Moreover, the shape of the leading edge could be sharp at high rotational velocity and round at low rotational velocity. In addition, a theoretical model for predicting the dimensionless wetting area was developed based on geometric analysis.