• 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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.398-401
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• 2007

The performance characteristics of Polyethylene-Nitrous oxide (PE-N2O) hybrid rocket motor with the variation of the grain geometry was investigated. To compare the performance parameters under the different port number, single and four port grains were used in this study. In order to improve the performance by enhancing mixing between fuel and oxidizer, the fuel grain having the mixing chamber was additionally studied. From the motor firing tests, it is found that the motor having 4-port fuel grain with the mixing chamber showed the highest performance among all cases. Therefore we have confirmed that with only the geometrical change of the fuel grain, it was possible to give quite influential improvement on the motor performance

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.1
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• pp.7-14
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• 2011

In this study, the measurement uncertainty of combustion experimental system and experimental parameters for hybrid rocket were evaluated by B type evaluation method. The measurement uncertainty of all experimental parameters was lower than 3%. The highest value of expanded uncertainty was characteristic velocity efficiency with 2.83% and the expanded uncertainty of regression rate which is the design and performance parameter was indicated to 0.03%. These results shown that the reliability of hybrid combustion system was located within allowed limits.

• 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.

• Advances in aircraft and spacecraft science
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• v.4 no.3
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• pp.281-296
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• 2017

The axial-injection end-burning hybrid rocket proposed twenty years ago by the authors recently recaptured the attention of researchers for its virtues such as no ${\zeta}$ (oxidizer to fuel mass ratio) shift during firing and good throttling characteristics. This paper is the first report verifying these virtues using a laboratory scale motor. There are several requirements for realizing this type of hybrid rocket: 1) high fuel filling rate for obtaining an optimal ${\zeta}$; 2) small port intervals for increasing port merging rate; 3) ports arrayed across the entire fuel section. Because these requirements could not be satisfied by common manufacturing methods, no previous researchers have conducted experiments with this kind of hybrid rocket. Recent advances in high accuracy 3D printing now allow for fuel to be produced that meets these three requirements. The fuel grains used in this study were produced by a high precision light polymerized 3D printer. Each grain consisted of an array of 0.3 mm diameter ports for a fuel filling rate of 98% .The authors conducted several firing tests with various oxidizer mass flow rates and chamber pressures, and analysed the results, including ${\zeta}$ history, using a new reconstruction technique. The results show that ${\zeta}$ remains almost constant throughout tests of varying oxidizer mass flow rates, and that regression rate in the axial direction is a nearly linear function of chamber pressure with a pressure exponent of 0.996.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.233-236
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• 2007

In this paper, thermal sensitivity of the solid fuel grain in the hybrid rocket motor was investigated. When the heat from the non-reacting hot flow passing the grain ports is transferred to the solid fuel grain, the temperature fields in the solid fuel was numerically analyzed. These numerical analyzes were performed under the different nine port radii, and the critical distance between the ports in which the temperature in the solid fuel is sensibly responding was determined. Thus, the critical distance between the ports would be the important consideration for the design of the fuel grain because the high temperature in the fuel can bring the structural problems.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.244-248
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• 2012

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. The interaction of vortex shedding in the pre-chamber and small-scale vortices adjacent to burning surfaces by using combustion test.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.14 no.4
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• pp.17-23
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• 2006

This paper describes the preliminary design procedure for the hybrid propulsion system. For a given mission defined by velocity increment, the design of a polyethylene/LOX hybrid rocket was implemented. In addition, Seven-cluster multi-port fuel-grain was considered. After determining the system size including the combustion chamber, the performance parameters such as specific impulse, thrust, characteristic velocity, and thrust coefficient can be predicted by using empirical regression rate correlation, though most of preliminary design code assume constant regression rate. The results of the performance prediction indicated that besides the widely used HTPB/LOX, polyethylene/LOX hybrid motor can be a viable alternative to the more widely used SRMs.

• 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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• 2008.11a
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• pp.257-260
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• 2008

In order to control thrust of propulsion system, we built the 50 Newton level PE-GOx hybrid rocket, and changed the mass flow rate of GOx. From the preliminary experiential results, we could see possibility of controlling thrust of hybrid rockets by controlling mass flow rate of GOx.