Design, fabrication and testing of a high-impulse, low-power microthruster using liquid propellant with high viscous fluid plug팽창 유체와 고점성 유체 마개를 이용한 고출력 저전력형 마이크로 분사기의 설계, 제작 및 시험
This thesis presents the design, fabrication and testing of a high-impulse and low-power microthruster using the liquid propellant of low boiling temperature and the fluid plug of high viscosity.
In the theoretical study, we develop thermodynamic and hydrodynamic models to find the relations between electrical energy input and mechanical impulse output. From the thermodynamic model, we estimate the temperature and the pressure of a liquid propellant using an equivalent circuit model. From the hydrodynamic model, we obtain the ejection velocity of a droplet using the pressure of the liquid propellant, obtained from the thermodynamic model.
In the experimental study, we fabricate a heater, electrical lines and a propellant channel on the bottom glass layer by surface-micromachining technique. We also fabricate a fluid plug channel and feed holes on the middle silicon layer by ICP RIE process. The bottom and middle layers are assembled with the upper polymer layer having the feed holes of the fluids and electrical wire. The fabricated microthruster has the size of 7±0.25mm×13±0.25mm×1.5±0.25mm.
We measure the output impulse bit of the fabricated microthruster, using two types of liquid propellants, water and perfluoro normal hexane (FC72), having different boiling temperature and two types of fluid plugs, water and oil, having different viscosity. We also measure the output impulse bit of the microthruster supplying three different pulse widths of input signal to three different heaters. The experimental results are compared with the theoretically estimated values.
The impulse bit of $6.21±0.29×10^{-8}Nㆍsec$ is obtained from the microthruster using the perfluoro normal-hexane (FC72) propellant having the boiling temperature of 59°C and the oil plug having the absolute viscosity of 0.3Nㆍsec/㎡ for the electrical input energy of 0.4±0.02 mJ. The microthruster using the oil plug generates the impulse bit, two times larger than the microthruster using the water plug. ...