The Characteristics Of High Viscosity Piezoelectric Micro Jet

As the activities of space development in the world, a large number of spacecrafts are launched into space. Since Shenzhou 8 spacecraft and Chang'e II were successfully sent into the space, the quantity of the online spacecrafts has grew a lot, manned space program has been the major scientific research projects in China. Long-term orbit spacecraft in the space often has lubrication failure because of the space environment. The life of the spacecrafts had been mainly affected by the life of electronic components of the equipment before, but in recent years, as the development of electronic technology, the main factor which decides the life of the spacecraft has turned to the life of the mechanical parts from the electronic parts. The lubrication conditions affect the life of the mechanical components of the spacecraft a lot. If we want to improve the life of the spacecraft online, we have to improve the lubrication conditions. Currently the liquid lubricant is the most effective means of lubrication, because of its lower mechanical noise, friction coefficient, energy consumption and it is not sensitive to the space environment. Also the liquid lubricant can take away the wear material of the equipment. The online spacecrafts need to be lubricated properly on time. If the liquid lubricant is supplied more than they need, the extra lubricant oil will evaporate and pollute the optical instruments on the spacecrafts. On the other hand, the cost of the launching is very sensitive to the weight of the spacecrafts, so the amount of the lubricant should be as minimal as possible. The liquid lubricant should satisfy the need of the spacecraft. This research project derives from the National Natural Science Foundation of China. A kind of high-viscosity piezoelectric micro jet has been designed based on the principle of the piezoelectric on-demand-drop technology. This device is kind of on-demand-drop jets. The experiments of jetting glycerol and lubricant oil have been studied. This research has done a lot of work for the application of the device on the spacecrafts.Considering lubrication failure of the moving parts in spacecraft, a kind of high-viscosity piezoelectric actuated micro jet has been developed. A kind of micron scale ejection hole has been fabricated by heating the glass tube and pulling it while hot. The prototype of the device has been built. Based on the DDS theory, an arbitrary wave signal generator has been developed with FPGA. The piezoelectric ceramic has been simulated with the FEA. The glycerol of 50% and 95% consistency with high viscosity and the lubricant oil has been used to be jetted in the experiments. The frequency, voltage, holds time of the waveform and the liquid height in the tube has been studied. The results show that with the increase of liquid height, the optimal driving frequency decreases; with the viscosity of glycerin increases, the required voltage increases. With the optimal dwell time, the lower of the liquid height, the lower voltage is needed. With the liquid viscosity increases, frequency bandwidth which can form stable injection gets narrower.