• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.3
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• pp.247-255
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• 2016

The purpose of this study is to investigate unsteady-state characteristics of a pintle thruster with various pintle speed. Based on steady state experimental results, non-linear pintle stroke equation is obtained and applied to the unsteady state experimental system. For the unsteady state experiments, three different pintle speeds are used: 3.10 mm/s, 5.65 mm/s, 10.83 mm/s, respectively. Results show that backward pintle stroke results in faster convergence time because of high chamber pressure during backward pintle stroke sequence. During the forward and backward process, thrust curve shows singular points. These phenomenons is caused by variation of mass flow rate, which is mainly due to changes of both chamber pressures and nozzle throat area. This behavior becomes distinctive for a faster pintle speed case.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.3
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• pp.15-20
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• 2013

The graphites as airtight structure seals prevent high-pressure and high-temperature gas from flowing into actuator of propulsion system and generate lubricant film during wear procedure to assist lubricant and sealing. In this study, the tribological characteristics of the graphite in high-temperature are evaluated. In order to evaluate the tribological characteristics of high density graphite(HK-6), variables which are temperature, sliding speed and contact load are set. this study suggest optimized environment conditions through the wear properties of graphite. Consequeantly, high temperature is better than at room temperature to generate lubricant film, so that friction coefficient of graphite is lower at high temperature than at room temperature.