• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2524-2527
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• 2007

Solid propellant gas generators (SPGG) play a role as a turbopump starter in liquid propellant propulsion systems by supplying pressurized gas to power turbines for engine start. For such a purpose, the propellants should burn with a relative low flame temperature and the combustion gas should not contain corrosive constituents such as chlorine compounds. In accordance with these requirements, stabilized AN-based propellants have been usually used as the most appropriate oxidizer for propellant compositions. However, the burning area of the propellant intends to increase to satisfy the required mass flux because of its low burning rate. Consequently the burning area incensement brings on the SPGG size augmentation. A flow restriction such as filters is applied to decrease the SPGG size by rising up the combustion pressure resulting in increasing the burning rate. The feasibility of the size reduction of SPGG by the employment of filters have been studied. The preliminary results of this study show that the considerable reduction of SPGG size would be achievable just by installing a filter with relatively high pressure loss coefficient.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.219-222
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• 2009

Pyrostarters play a role as a turbopump starter in liquid propellant propulsion systems by supplying pressurized gas to power turbines for engine start. A rupture disk in pyrostarters, which is usually installed behind a nozzle throat, not only isolates the charged solid propellants from the external environment but also improves the ignitability of the solid propellants by increasing a chamber pressure at the beginning of combustion. Experimental tests have been performed to study the effects of rupture disk thickness, depth and shape of scores, and pressure build-up rates on burst pressures and burst diameters. The experimental results show that the developed rupture disk fulfills the performance requirements expected in a real operational condition.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.664-667
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• 2010

Solid rocket propulsion systems are generally used for tactical missiles due to the structural and operational simplicity. Nevertheless, various kinds of design factors including outer diameter, length, weight, loading efficiency of propellant grain effects to thrust performance. Dual thrust is beneficial to range extension and terminal velocity increasement. But loading efficiency becomes low in case to obtain dual thrust performance by burning surface control. So, It is predicted to be reasonable to obtain dual thrust performance with high/low burning rate propellants. This study is on internal ballistic analysis and ground test to confirm dual thrust performance.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.4
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• pp.33-40
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• 2020

A sturdy on the adhesion properties of solid propellants, liners, and insulation was carried out according to the types of barrier coats. A barrier coats were used to prevent migration of the plasticizer or curative between the propellant/liner/insulation, and the barrier coat was selected out of Isocyanates with different molecular weight and number of -NCO in one molecule. As a result, it was found that the more the -NCO group and the larger molecular weight, the stronger adhesion. In addition, as a result of experiments about effects of the pot life after applying the barrier coat on bond strength, the adhesion strength was shown to increase as the pot life was short.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.10
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• pp.813-820
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• 2021

In this study, a low-velocity impact test was performed to obtain the dynamic properties of solid propellants. The dynamic behavior of the solid propellant was examined by measuring the force and displacement of the impactor during the low-velocity impact test. The bending displacement was calculated by compensating for the local displacement caused by the low-velocity impact test in the form of three point bending and the shear displacement caused by using a short and thick solid propellant specimen. Stress and strain were calculated using compensated displacements and measured force, and dynamic properties of solid propellants were obtained from the stress-strain curve and compared with static bending test. The dynamic properties of solid propellant under the low-velocity impact loading at various operating temperature conditions such as room temperature(20 ℃), high temperature(63 ℃), and low temperature(-32 ℃) were compared and investigated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.275-282
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• 2008

This paper presents numerical investigation of multi-phase flow in solid rocket motor nozzle and effect of multi-phases on the performance prediction of the Solid Rocket Motor. Aluminized propellants are frequently used in solid rocket motors to increase specific impulse. An Eulerian-Lagrangian description has been used to analyze the motion of the micrometer sized and discrete phase that consist of the larger particulates present in the Solid Rocket Motor. Uniform particles diameters and Rosin-Rammler diameter distribution method has been used for the simulation of different burning of aluminum droplets generating aluminum oxide smokes. Roe-FDS scheme has been used to simulate the effects of the multi-phase flow. The results obtained show the sensitivity of this distribution to the nozzle flow dynamics, primarily at the nozzle inlet and exit. The analysis also provides effect of two phases on performance prediction of Solid Rocket Motor.

• Polymer Science and Technology
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• v.1 no.4
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• pp.211-215
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• 1990

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.383-386
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• 2006

Several HTPB/AP and HTPB/AP/HMX propellants were investigated experimentally for ignition characteristics in subatmospheric pressure. The threshold ignition pressure was 4psia for HTPB/AP composite propellant. The partial replacement of AP in HTPB/AP composite propellant by $5\sim15%$ of HMX, HNIW showed improvements in the threshold pressure was below 0.4psia. This appears to be due to the exothermic dissociation characteristics of HMX and HNIW at lower temperature $(\sim220^{\circ}C)$ than that of AP. The ignition substance B/KNO3 was coated thinly on the propellant surface for better ignition effect. As a result, ignition delay time of 15% was improved. NC is applied to $B/KNO_3$ ignition substance as a secondary binder and $NC-B/KNO-3$ suspension solution is coated to the propellant surface.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.177-180
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• 2009

This study was investigated to know the thermal decomposition for the propellant ingredients and 2 kinds of HTPE propellants. The thermal analysis of the propellant ingredients used in this study showed that the thermal stability of these materials decreases in the following order : AP > HTPE > AN > BuNENA. In addition, propellant HTPE 002 containing AN showed that an endothermic process at around $125^{\circ}C$ corresponding to the solid-solid phase change($II{\rightarrow}I$) of AN was followed by the exothermic process due to decomposition of BuNENA/AN until $200^{\circ}C$. The critical temperature, $T_c$, of thermal explosion for the propellants HTPE 001 and HTPE 002, were obtained from the non-isothermal curves at various heating rates, by using Semenov's thermal explosion theory. Kissinger's method was employed to obtain the activation energy of the thermal decomposition, and it was used to calculate the $T_c$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.2
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• pp.91-97
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• 2002

Dynamic extinction of solid propellants subjected to rapid pressure drop was studied with the aid of energy equation of condensed phase and flame model in gas phase. It is found that the total residence time($\tau_\gamma$) which measures the residing time of fuel in the reaction zone may play a crucial role in determining the dynamic response of the combustuion to extinction. Residence time was modeled by various combinations of diffusion and chemocal kinetic time scale. Effect of pressure history coupled with chamber volume on the extinction response was also performed and was found that dynamic extinction is more susceptible in a confined chamber than in open geometry. And, dynamic extinction was revealed to be affected profoundly by diffysion time scale rather than chemical kinetic time scale.