Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/47635
Title: VAPORIZING LIQUID MICROTHRUSTERS FOR MICROSPACECRAFT APPLICATIONS
Authors: KUMARASAMY KARTHIKEYAN
Keywords: Microspacecraft, Micropropulsion,Ceramic thruster,liquid propellant,ignition circuit, steady mode,pulsed mode
Issue Date: 15-Feb-2013
Source: KUMARASAMY KARTHIKEYAN (2013-02-15). VAPORIZING LIQUID MICROTHRUSTERS FOR MICROSPACECRAFT APPLICATIONS. ScholarBank@NUS Repository.
Abstract: In recent years, miniature satellites or micro spacecraft are increasingly being launched to perform a wide variety of scientific, security and commercial missions in space. A micro spacecraft is defined in the present study as a spacecraft with a mass between 1 to 100 kg. In the operation of a micr0spacecraft, a micro propulsion system is required for station keeping, orbit maintenance and attitude control. Currently, most micro propulsion devices are fabricated by using silicon material. A class of material called Low Temperature Co-fired Ceramics (LTCC) is an alternative material to silicon that can offer merits of simple fabrication process involving multi-layer channels, high temperature capability, and ability to embed conductive materials in the device. This present work describes the development of a vaporizing liquid microthruster (VLM) for the first time using the LTCC technology. The VLM consists of an inlet, vaporization chamber, an internal resistive heater for vaporizing a liquid propellant, and an in-plane convergent-divergent nozzle to create the required thrust. Two new operational modes (constant power and constant temperature) are proposed in the present study for continuous VLM stable mode operation. The operational modes are accomplished by designing a new ignition circuit consisting of a power supply, a PID temperature controller and a solid state relay integrated into a VLM module. The experimental investigation involved the design and construction of a rig and thrust measurement system that allowed performance of the microthruster under near-vacuum conditions. The experimental rig enabled the VLM to reach stable mode of operation in the quickest time from the starting point. Performance characterization of the VLM was studied at sea level and vacuum conditions. A new method for micro-thrust measurement of water vapor jet was proposed in this study. A maximum thrust of 967 µN was measured during VLM operation in near-vacuum conditions. Steady state mode was achieved in record time of 6.0 s. This value is the best reported response time in the literature. Finally, a new method for pulsed mode VLM operation was studied. A micro-solenoid valve controlled by the Labview software was able to achieve the short impulse bits from the VLM as if produced by a solid propellant microthruster.
URI: http://scholarbank.nus.edu.sg/handle/10635/47635
Appears in Collections:Ph.D Theses (Open)

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