• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.14-17
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• 2011

Numerical simulation was carried out for the SNECMA modulatable thrust devices, with four different nozzle contraction angle $45^{\circ}$, $60^{\circ}$, $83^{\circ}$, and $90^{\circ}$, respectively. Results show that $83^{\circ}$ nozzle contraction is better in that it comes up with good thrust level with small aerodynamic load.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.153-156
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• 2011

Steady state experiment was carried out for modulatable thruster applications, with four different pintles. Results show that thrust can be modulated by changing nozzle throat area with pintle penetration. However, effect of pintle shape on the thruster performance is yet to be concluded.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.78-84
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• 2020

The performance of pintle thruster is analyzed by using the pintle thruster performance analysis model which integrating the element models introduced in Part I. To verify the performance analysis, the results of the developed program are compared with the experimental data of kerosene/hydrogen peroxide liquid pintle thrusters. Based on the results, the characteristics of the pintle thruster are analyzed. The sensitivity analysis is performed to investigate the effect of thruster shape and operation parameters on performance characteristics using both OAT and scatter plot methods. The four performance parameters such as droplet diameter, film flow rate, O/F ratio, and nozzle throat diameter are evaluated to investigate their effects on characteristic speed, combustor pressure, and specific thrust.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.14-21
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• 2010

Ion thruster is a kind of electrostatic thruster that use electrostatic field in order to accelerate ionized propellant. Ion thruster have characteristics of small thrust but very high specific impulse among the electric thrusters. High specific impulse can reduce propellant consumption significantly. So, ion thruster have advantage for long time and long distance mission. Recently, plans for space exploration is increasing gradually not only at traditional forward countries for space like USA, Russia and Europe, but also other countries like Japan, China and India. Exploration for superior planets and asteroids the propellant ratio can go up to about 99% when chemical propulsion is used as a cruising thruster. Therefore, latest space exploration vehicles use the ion thruster as main thruster for del-V burn and use monopropellant thrusters for attitude control. In this paper, the development process of preliminary ECR ion thruster and the ECR discharge test results will be presented.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.49-52
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• 2009

The response times of monopropellant thrusters at a pulse mode were investigated experimentally as design parameters and feed pressure conditions. Five different model thrusters as injection direction/uniformity, aspect ratio of reactor, volumes of manifold and chamber were designed. As a results, two parameters, aspect ratio and manifold volume, were directly related to response characteristics. Additionally, chugging instability at reaction chamber was observed when pressure drop across the catalyst bed was increased due to high aspect ratio or when low pressure was built at reaction chamber.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.1
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• pp.28-36
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• 2016

Theoretical model of a variable thrust solid rocket motor with a pintle nozzle was derived. For the chamber pressure control, classical model linearization and proportional-intergral controller was used. And then two types of gain scheduling controller were suggested to imporve controller performance for the non-linear propulsion model. Considering characteristics of systems, control gains were scheduled by chamber pressure or free volume. Step responses of each controllers were compared. As a result, the proper control algorithm about characteristics of variable thrust rocket motor was suggested.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.3
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• pp.76-86
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• 2008

The EP(electric propulsion) is unique in that several energy sources can be utilized to produce the electric energy and that high exhaust velocity can be achieved compared to the conventional chemical propulsion. Though a lot of variety of non chemical propulsion are under study, the fact that the EP's specific impulse ranges widely from 200s to 5000s led most research to concentrate on the electric propulsion research. This paper, therefore, is aimed to introduce the up-todate existing EP family such as electrothermal, electrostatic and electromagnetic thrusters where its operating concepts, characteristics and possible variants are presented for future applications.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.10
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• pp.60-66
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• 2004

Redundant thrusters are generally adopted to satellite designs for a highly reliable attitude control system. So efficient redundancy management is required to take advantage of these redundant thrusters. In this paper, control allocation method is proposed as a method for controlling redundant thrusters. Control allocation is a method to calculate optimal distribution on redundant controls for realizing desired forces/torques. It is shown that a control allocation problem for redundant thrusters is formulated as a linear programming problem which minimizes fuel consumptions with thrusters, constraints. We also show that the proposed method is more efficient than an existing method by numerical examples.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.8
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• pp.141-147
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• 2002

Estimation of thrusters efficiency is a very important process at the end of lifetime of a satellite. This paper introduces a technique to estimate the efficiency change of thrusters considering bubble effect for Koreasat I. During APEMAC(Automatic Pitch Error/ Momentum Adjust Control), the change in thruster efficiency is estimated to compare the attitude telemetry data of the Koreasat I with the results of the control logic using Simulink. The outcome of this study is expected to contribute to improving the operational load at the end of generic communication satellite mission.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.135-138
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• 2007

Two-dimensional distribution characteristics on the spray droplets emanating from an injector employed in a liquid-propellant thruster are investigated through dual-mode phase Doppler anemometry (DPDA). Spray-breakup characteristic parameters such as spray droplet velocity, turbulent intensity, Sauter mean diameter (SMD), number density, and volumetric flux are quantified to scrutinize the macroscopic behavior of injector-spray breakup. The present study will be able to contribute to the comprehension for performance features of the thruster in current use and to the design engineering of a brand-new thruster as well.