Research On Piezoelectric Micro-jet Device Based On Resonance Driven

In recent years, reports of the new success in space programs have kept pouring in such as the manned space mission and the lunar exploration program, which marked the research strength of China’s aerospace has been developing toward the international forefront. However, aerospace engineerin g is actually a high investment and high cost research, and also the in-orbit spacecrafts are often easy to get mechanical failure due to the effect of extreme environment in space. Fortunately, more and more studies revealed that the friction and wear of mechanical moving parts caused by lubrication failure made up a main reason for the failure of spacecraft. Presently, a lot of studies have been conducted to solve the problem of space lubrication failure from domestic to abroad, but a mature solution is still not found so far. Some technical bottlenecks have not been properly solved such as oil supply, oil storage and seal, etc. Moreover, space lubrication technology is the core technology to any countries, secretive attitude has always been taken to deal with it. Therefore, in order to meet the needs of space exploration in future, independent research should be carried out firmly. In this paper, a piezoelectric micro-jet generator which takes the control moment gyro(CMG) as specific application object is proposed. The device is featured by some typical advantages such as small volume, light-weight, compact structure, embedded convenient, fine insulation and sealing, etc. By controlling the parameters of pulse voltage which is applied to piezo ceramic elem ent, it can obtain regular and quantitative spray of lubricating oil. Oil supply could be achieved through this method and the technical problem of lubrication failure will be solved hopefully.In this paper, the working principle and the structure of the device were described in detail firstly. The finite element model of the piezoelectric vibrator was established. The modal analysis of the vibrator considering the effect of fluidic added mass was conducted. In order to optimize the actuating performance of the piezoelectric vibrator, the effects of the factors such as fluidic added mass, the thickness of the piezoelectric ceramic, the thickness of the metal diaphragm, liquid density, and the thickness of liquid layer on the resonance frequency and the maximum amplitude were analyzed. Also the effects of pulse voltage waveform on the vibration displacement and vibration velocity were studied. In view of fluid-structure coupling problem of the generator, the vibration displacement response of the piezoelectric vibrator and the pressure distribution of the flow field under the excitation of a single pulse were researched, which based on the simulation platform of MFX-ANSYS/CFX. The multi-phase computational fluid dynamics(CFD) software was used to analyze the droplet ejection process, and the effect of the pulse parameters and the fluid parameters on the liquid injection performance were also analyzed. Finally, the characteristics of the micro-jet device were studied by actual experiment. The influence of the fluid on the resonance frequency and vibration mode was analyzed, and the effects of the pulse waveform, pulse duty ratio and liquid viscosity on the injection performance were studied.