A new three-dimensional mathematical model is proposed to predict the shape of accreted ice on helicopter rotors. The model assumes that ice accretion on a rotor’s surface occurs by flow and solidification of a thin water film on its surface. The model is developed by analyzing conservation of mass, momentum, and energy in the thin water film on a rotating curved surface. The model is expressed in rotating body-fitted nonorthogonal curvilinear coordinates, and the Coriolis-force term in the momentum equations is neglected because its effect is relatively small compared with that of the centrifugal force. The computational method is presented to solve the model, and the model is validated by comparing its results with published experimental data. The results show that the proposed model accurately predicts both the water-film thickness and the ice-layer thickness on a rotating surface. Additionally, the model has been used to study how the rotor angular speed and MVD (Median Volumetric Diameter) of the droplets affect ice accretion. The results show that an increase in both angular speed and MVD can lead to a thicker layer of ice, while the effect of MVD on ice accretion near the stagnation point becomes unobvious when MVD is larger enough.

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In order to solve the problem of diamonds sedimentation in electroplating tank and uneven distribution of diamonds in coatings, the fluid flow in the electroplating tank formed by three structure kinds of agitation pipe was compared and analysed. Results showed that the middle inlet type agitation pipe can significantly improve the fluid uniformity in the electroplating tank, and setting sand blasting ports at both ends of the agitation pipe can avoid the formation of fluid “dead zone”. Along the direction of the agitation pipe, the middle inlet type agitation pipe improves the overall flow of the fluid. In the position of the wire saw passing through, the difference of the speed in the electroplating tank of the middle inlet type is 47.17% and 15.25%, which is significantly lower than that of the water inlet structure of one end by 134.48%. As a result, it can significantly improve the plating effect of the wire saw.