Numerical simulation and theoretical analysis of viscous pump performance

The influence of geometry parameters on the outlet volume flow rate is studied for the viscous pump section of crankshaft pump by using numerical method which is validated by experimental data. It is found that the volume flow rate monotonously decreases with the increase of spiral angle, and increases with the increase of spiral groove width; there is an optimum spiral groove depth to maximize the volume flow rate. Whereafter, a theoretical model of viscous pump based on fluid dynamics is established, and an analytic formulation of outlet volume flow rate is obtained. The volume flow rate predicted by the theoretical model agrees well with the numerical simulation result. Based on the theoretical model, it is found that the increase of spiral angle will reduce the viscous driving force and simultaneously strengthen the gravitational blocking effect, which leads to the decrease of volume flow rate; the variation of groove width has little effect on the viscous force and only linearly changes the area of transverse section, so the volume flow rate increases with the increase of groove width; the variation rates of viscous driving force and gravitational blocking effect with the variation of groove depth are not identical, which results in an optimum groove depth to maximize the volume flow rate. This theoretical model of viscous pump can be applied in research and design of pumps with similar working mechanism.