• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.1
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• pp.58-67
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• 2021

This paper describes the development for the dual thrust rocket motor with two types of propellants with different combustion characteristics. We developed the composition of two kinds of propellant to be applied to a rocket motor, and improved a propellant charging process in a free grain type to improve the adhesion method and the problems of adhesion between different propellants. In addition, to meet the ignition phenomenon as a small rocket motor, the ignition delay was improved by applying a nozzle plug developed in a high density foam. The propulsion rocket motor reflecting this design and the improved manufacturing process was evaluated through a ground performance test.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.87-95
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• 2016

A study on the effect of altitude-compensation and the possibility of throttling is performed by designing an E-D nozzle that is a type of altitude-compensation nozzles. In order to examine the effect of the altitude-compensation, a CFD analysis is conducted by using three kinds (sea level, altitude at 10 km and 16 km) of the atmosphere condition while maintaining the chamber pressure. Results show that the effective nozzle exit area is also gradually increased when the altitude get increased. Understanding the possibility of throttling, a CFD analysis is conducted by moving the location of the pintle. Just as same as a general pintle thruster, the chamber pressure and thrust are increased when the nozzle throat area get decreased.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.11
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• pp.874-882
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• 2013

Kerosene(Jet A-1), one of the propellants for each stage's engine of the Korea Space Launch Vehicle-II(KSLV-II), functions as coolant at the same time as it flows inside the cooling jacket of the combustion chambers and is injected through the film cooling holes. A physical surrogate mixture model to reproduce the thermophysical characteristics of Jet A-1 has been selected and the thermodynamic/transport properties of the model fuel under high pressure including supercritical conditions have been estimated using SUPERTRAPP(NIST SRD4). Comparisons with the measured properties suggest that proposed database can be used to extract properties of Jet A-1 for conjugate heat transfer analysis of liquid propellant rocket engine thrust chambers. Predicted combustion/cooling performance of regeneratively cooled thrust chambers shall be validated through comparisons with upcoming firing test results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.3
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• pp.29-37
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• 2000

In this paper, the thrust control of PWM Inverter-fed SLIM(Single-sided Linear Induction Motor) is achieved by vector control and PID control with DSP(TMS320C32). SLIM which used as a conveyor has required the quick response and the constant operating without air gap trembling while it conveys load.Thus, SLIM should have the smallest trembling of air gap length. First, voltage equations for SLIM are calculated from the proposed equivalent circuit in this peper, and not only the exciting current but also the thrust component are obtained from them. The thrust current ripple can be reduced by the vector controller using a slip angle frequency, and the PID controller is also use for the position control.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.164-170
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• 2007

In this paper, the development results of electromechanical TVC actuation system is described in the aspect of design, analysis, manufacturing and test. The kinds of prime power for TVC actuation system is classified by the variety of propulsion system of launch vehicle. The electric power by battery is the sole candidate for prime power of TVC actuation system at the view point of feasible domestic infra technologies for the present. The characteristic analysis study is performed between electromechanical and electrohydraulic actuation system with respect to power efficiency, performance and weight efficiency. The electromechanical actuation system has superiority of power and weight efficiency according to less opportunity of power conversion process.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.281-285
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• 2007

The flow characteristics in the thruster should be analyzed considering its geometry and the pressure ratio to estimate its performance and etc. This paper suggests the computational result of an axisymmetric real nozzle for the altitude control of a satellite to find out the application limit that the assumption of continuum mechanics holds. The steady non-reacted compressible flow field in the unstructured grid system is computed and analyzed with varying the environmental pressure (or the degree of vacuum) under the fixed pressure ratio in a real thruster of which the area ratio of exit to throat is 56. The assumption of the continuum mechanics is not approved when the environmental pressure is reduced less than $10^{-3}$ atm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.2
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• pp.175-180
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• 2009

In this article, we fabricated polytetrafluoroethylene(PTFE) nozzle treated by ion beam, in order to fabricate polymer based electrospray micro thruster with super hydrophobic nozzle. To obtain the super hydrophobic surface, PTFE surface is treated by argon and oxygen plasma treatment process. The optimal condition is investigated argon and oxygen flow rate as well as the paalied energy level for the treatment process. Fabricated nozzle was evaluated by measuring contact angle, and the surface morphology was examined by using scanning electron microscope(SEM) and atomic force microscope(AFM). We observe that jetting becomes more stable and repeatable on the treated nozzle. And to evaluate performance of fabricated nozzle, we measure micro scale thrust using a cantilever and a nozzle treated by ion beam laser displacement sensor.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.12
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• pp.986-993
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• 2018

Lateral thrust jet has better maneuverability performance than the control surface like the conventional fin for attitude control or orbital transition of guided weapons. However, in the supersonic region, a jet interaction flow occurs due to the lateral thrust jet during flight, and a complicated flow structure is exhibited by the interaction of the shock wave, boundary layer flow, and the vortex flow. Especially, hit-to-kill interceptors require precise control and maneuvering, so it is necessary to analyze the effect of jet interaction flow. Conventional jet interaction analyses were performed under low altitude conditions, but there are not many cases in the case of medium altitude condition, which has different flow characteristics. In this study, jet interaction flow analysis is performed on the lateral jet controlled interceptor operating at medium altitude. Based on the results, the structural characteristics of the flow field and the changes of aerodynamic coefficient are analyzed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.10
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• pp.791-799
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• 2020

Launched in October 2019, Northrop Grumman's MEV-1 was the world's first unmanned mission demonstrating the practical feasibility of on-orbit servicing. Although the concept of on-orbit servicing was proposed several decades ago, it has been developed to various mission concepts providing services such as orbit change, station keeping, propellant and equipment supply, upgrade, repair, on-orbit assembly and production, and space debris removal. The historical success of MEV-1 is expected to expand the market of on-orbit servicing for government agencies and commercial sectors worldwide. The on-orbit servicing essentially requires the utilization of a highly propellant efficient electric propulsion system due to the nature of the mission. In this study, the space mission analysis for a simple on-orbit mission involving Hall thruster is conducted, which is life extension mission for geostationary orbit satellites. In order to analyze the mission, design space exploration for various Hall thruster design variable combinations is performed. The values of design variables and operational parameters of Hall thruster suitable for the mission are proposed through design space analysis and optimization, and mission performance is derived. In addition, the direction of further improvement for the current on-orbit mission analysis process and space mission analysis involving Hall thruster is reviewed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.411-413
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• 2009

This paper deals with supersonic vehicle. A supersonic vehicle has very complicated and high nonlinear thrust characteristics with respect to outer and inner environment during operation. For this reason, supersonic vehicle has many maneuver constraints and allows to operate within more narrow flight envelope. In this paper, trajectory optimization of supersonic vehicle is accomplished. The trajectory optimization problem is formulated by a discrete parameter optimization problem and the operation constraints are considered during trajectory optimization. It is shown that results of trajectory optimization give senses to fuel supply and nozzle throttle area control into effectiveness. Furthermore, general operation direction and its application for supersonic vehicles are discussed.