• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.370-373
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• 2007

In this study, a hybrid rocket motor with separable and detachable oxidizer tank from combustion chamber is developed. Initially, the measured thrust of the motor showed about 30% of the design thrust since the oxidizer supply was not enough. In order to solve this problem, application is made to expand the orifice diameter of oxidizer injector empirically, so that the mass flow rate of oxidizer was improved. The improved performance was about 60% of design thrust, 18kgf, and thrust-to-weight ratio was reasonable, compared with other sounding rockets.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.251-254
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• 2004

Hybrid rockets have many advantages over solid and liquid rockets. Hybrid rockets put forth high $I_{sp}$ like liquid rockets in spite of simple structure and low cost. As oxidizer flow rate is increased, thrust of hybrid rocket is increased accordingly. In this study, lab-scale hybrid rocket is designed, fabricated and tested. This system consists of lab-scale hybrid rocket motor, ignition system, flow system and data aquisition system. In order to control oxidizer flow rate, we construct flow rate control system by using needle valve and stepping motor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.97-100
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• 2008

A hybrid sounding rocket carrying about 10kg payload reaching up to 15km altitude has been designed. The commercial seamless aluminium tube and liquid ${N_2}O$ without pressurization devices were chosen as rocket motor case and oxidizer supply system respectively. A hybrid rocket engine performing required propulsion impulse is designed with time dependent internal ballistic scheme. Engine performance, aerodynamic characteristics, and trajectory were predicted by a integral technique of internal ballistics and external ballistics. The design results were evaluated by comparison with previous experimental data, technical reports, and literatures.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.53-56
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• 2005

Hybrid rocket had many advantage with compared to solid and liquid rockets. In this study, swirl flow hybrid motor was designed and manufactured. And the methods of regression rate improvement wire considered. Thrust was calculated with pressure of the combustion chamber and the regression rate was measured in low flow rate of oxidizer. Several problems and solutions of operating hybrid rocket was presented.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.311-317
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• 2005

Hybrid rocket had many advantage with compared to solid and liquid rockets. In this study, swirl flow hybrid motor was designed and manufactured. And the methods of regression rate improvement were considered. Thrust was calculated with pressure of the combustion chamber and the regression rate was measured in low flow rate of oxidizer. Several problems and solutions of operating hybrid rocket was presented.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.649-652
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• 2011

A series of hybrid rocket combustion experiments were carried out with PMMA/GOx changing diameter and length of the disk installed at pre-chamber. The disk can generate vortex shedding flow and change flow conditions prior to entering the fuel grain which could also alter the combustion characteristics and pressure oscillations. Isolated dimple-like surface roughness patterns distributed all over the fuel surface, which can be thought of as a realization of the inherent flow instability. It is very likely that the formation of cell structures is originated from the modification of boundary layer characteristics of an entering oxidizer flow caused by a blowing effect mainly taking place near the wall. This coincided with our LES results. It would be a meaningful basis to understand combustion instability of hybrid rocket motor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.526-529
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• 2009

In this study, we analyze the characteristic of burning classified by a propellant according to a flux of an oxidizer to analyze propellant regression distance in accordance with a thrust control and burning time of hybrid rocket using hybrid combustor of Lab-Scale. To control a flux of an oxidizer, we design flow control system to regulate the mount of opening and shutting of a needle valve by a driving of stepping motor by a combination the needle valve with stepping motor. We derive the relationships between mass flow rate and regression rate according to a propellant through the oxidizer flux change. While doing the thrust control, we estimate regression distance through the oxidizer flux in accordance with thrust and confirm the creditability through the actual thrust control burning experimentation.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.71-78
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• 2007

An experimental investigation was conducted to clarify the combustion characteristics of Polyethylene-GOX(PE-GOX) hybrid motor using a single-port fuel grain configuration. Data from the experiments were analyzed to evaluate the length-averaged regression rate of PE-GOX propellants. Based on the existing theories, the empirical regression rate formulas provided from Marxman[3,4] and Altman[14] showed good concordance with the PE-GOX experiments. The accuracy of the regression rate was then evaluated and compared with the measured one. As a result, Marxman's model was somewhat more precise than Altman's model in these experiments. Moreover, the consideration of the empirical regression rate showed that O/F ratio has minor variation due to the quasi constant inflow of the fuel during motor firing.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.820-824
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• 2010

The purpose of this study is to develop basic technology of hybrid rocket vehicle by constructed and launched. This small hybrid rocket using HDPE/LN2O and Aluminium steel for its body (weight : 12.5 kg, diameter : 114 mm, height : 1.8 m) was designed. The fuel grain and injector were designed for 50 kgf thrust and burning time 2.5 sec. This rocket was loaded the data acquisition device for obtaining data of pressure and velocity during its flying and equiped an automatic ejector system using spring/motor and timer to collect the rocket more safely after launching. It was launched successfully, but found some problem that the rocket's weight was heavier than expected and the thrust was not enough to reach the designed altitude and analyzed its flight path way.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.2
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• pp.54-63
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• 2009

Large eddy simulation was conducted for flow development in a chamber with wall injection which simulates the cold flow in an idealized hybrid rocket motor. It was found that a peculiar timescale, roughly corresponding to St~0.5, resides in the flowfield resulting from the interaction between the main oxidizer and wall injected flows. However, the fact that this time characteristics is absent in the temperature field in the vicinity of the wall indicates that even a small regression rate renders the passive scalar, such as temperature, dissimilar to the velocity field. This implies that a classical approach, which assumes that constant turbulent Prandtl number, should be replaced by a more sophisticated turbulence models to accurately predict the temperature field in the hybrid motor.