Simulation of a piezoelectric micro-jet generator for high viscosity

Considering the active-feed lubrication for moving mechanical assemblies in the spacecraft, a kind of piezoelectric micro-droplet ejection generator for high viscosity liquid is proposed. In order to acquire the displacement-time curve of the centre of the metal film, the finite element analysis software ANSYS was used to analyze the driven part of the generator. The curve was fitted using Fourier series and the differentiated equation was obtained as the initial condition for the analysis of gas-liquid two-phase flow. The multi-phase computational fluid dynamics (CFD) software was used to analyze the droplet ejection process in order to obtain the influence of the pulse voltage amplitude, the minimum thickness of the flexible hinge, the dynamic viscosity of the lubricant and the nozzle diameter on the ejection parameters. The numerical simulation results showed that the generator can effectively achieve the controllable ejection of high viscosity liquid. Along with the pulse voltage amplitude increasing, the break up time decreased, but the length and velocity of the droplet increased. As the minimum thickness of the flexible hinge and dynamic viscosity increased, the break up time, the length and velocity of the droplet decreased. The nozzle diameter also had an important effect on the ejection parameters. As the nozzle diameter increased, the break up time increased, but the droplet length and velocity decreased.