Performance Estimation of a Capillary-Fed Evaporative Microthruster

Nanosatellites are important for carrying out short-term and cost-effective communication and surveillance missions. Their small size necessitates the need for propulsion systems that are lightweight, compact, and capable of delivering accurate reaction and attitude control while allowing for seamless integration with the satellite. This paper reports on a numerical analysis to determine the performance of a micro-electromechanical system (MEMS)-based vaporizing liquid microthruster that utilizes microtextured substrates for passive feeding of the propellant (water) using capillary force and subsequent thin film evaporation by localized heating. The generated vapor flows through a converging nozzle to produce thrust. The performance of the propulsion device is evaluated in terms of the mass flow rate, thrust, and specific impulse. The model demonstrates a unique way of integrating the evaporation characteristics at the liquid–vapor interface to real nozzle flow dynamics. The evaporation phenomenon at the liquid–vapor interface is captured by utilizing kinetic theory of the gases, and real nozzle flow is analyzed by considering compressible-slip flow through the converging nozzle. It is shown that the microthruster can generate a thrust of [Formula: see text] and an specific impulse of [Formula: see text] with a power input of approximately 3 W. The thrust and specific impulse efficiencies, when compared to quasi-one-dimensional isentropic values, are determined to range between [Formula: see text] and between [Formula: see text], respectively, for a power input of 0.2–3 W.