• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
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• pp.289-294
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• 2007

Solid Rocket Motor(SRM) has advantages such as - high specific impulse, operational safety and simplicity in design and manufacturing process, but thrust magnitude can't be controlled. For studying of pintle nozzle that can control the thrust magnitude of SRM, cold flow test and numerical analysis about needle type pintle shape were performed and results were presented in this paper. As the results of this study, pintle tip's shape and nozzle contour were important design parameters because thrust performance and variable thrust range of pintle nozzle depend on them. Especially, the thrust of needle typed pintle nozzle adopted in this test was predicted 13% higher than normal nozzle without pintle.

• Journal of the Korean Society of Propulsion Engineers
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• 제19권6호
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• pp.42-53
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• 2015

In this study, the influence of Al particle size, as an additive for solid propellant, on the mechanical erosion of the carbon-composite nozzle was evaluated. A new model which can predict the size and distribution of the agglomerated reaction product($Al(l)/Al_2O_3(l)$) was established, and the size of agglomerate were calculated according to the various initial size of Al in the solid propellant. With predicted results of the model, subsequently, the characteristics of mechanical erosion on the carbon-composite nozzle was estimated using a commercial CFD software, STAR CCM+. The result shows that the smaller the initial Al particles are, in the solid propellant, the lower is the mechanical erosion rate of the composite nozzle wall, especially for the nano-size Al particle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.162-166
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• 2005

A thermal resistance estimation of carbon/carbon composites used as the nozzle throat insert of solid rocket motor was performed using TPEM motor. Three types of TPEM motor and two types of propellant were employed. The ablation rate is higher for the higher chamber pressure and also higher for the higher concentration of oxidizing species in combustion gas, but it is lower for the higher material density.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.662-665
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• 2011

Pintle technology, which is one of the thrust control method for solid rocket motor, can control the thrust by the control of nozzle throat area through the pintle moving. For studying the unsteady flow characteristics of pintle nozzle by needle type pintle moving, cold flow test and numerical analysis were performed. The pressure distribution on the pintle tip was varied for pintle moving and stopping and thrust was varied by this effects.

• Journal of the Korean Society of Propulsion Engineers
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• 제10권1호
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• pp.30-37
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• 2006

A thermal resistance estimation of carbon/carbon composites used as the nozzle throat insert of solid rocket motor was performed using TPEM motor. Three types of TPEM motor and two types of propellant were employed. The ablation rate is higher for the higher chamber pressure and also higher for the higher concentration of oxidizing species in combustion gas, but it is lower for the higher material density.

• Journal of the military operations research society of Korea
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• 제3권1호
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• pp.83-96
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• 1977

The combustion chamber and nozzle of an end burning, small spherical rocket is designed. A spherical external shape has a number of advantages such as fixed center-of-gravity and minimum aerodynamic precession torques during flight and a better mass distribution for gyro-stabilization as contrasted to a conventional ogive rocket shape. It is shown that the cross-sectional variation of the end burning solid propellant with length is an exponential geometry to provide a constant thrust-weight ratio of the rocket device during the propellant burning period, and that the factors which affect the attainment of the constant relationship of thrust to weight in the design are the initial propellant area, initial weight of the rocket and propellant density. The measurement of the transient thrust in the ground static test using black powder propellant supports the predicted results. A wind tunnel having a $30{\times}30{\times}75cm$ test section and Mach number 0.11 is constructed, and a simple balance-type device is designed for the measurement of the drag of a spinning sphere. The experimental results indicate that the. spinning has no effect on the magnitude of the drag up to the Reynolds number $3{\times}10^5$. Numerical computation of the flight trajectories for various launching angles is presented, and the gyro-stabilization of spinning sphere is discussed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.477-482
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• 2009

Though rocket nozzle flow is very important to the rocket performance, the direct measurement is very difficult because of high temperature and high pressure gas flow. Then the experiment utilizing the hydraulic analogy has been developed for such a problem. Supersonic flows through an axisymmetric De Laval nozzle of solid rocket motor was simulated in a 2-D sluice-type water-table designed and manufactured utilizing hydraulic analogy. Methods to minimize or account for non-analogous effects in the hydraulic system must be reviewed for the quantitative application of the hydraulic analogy. In this application the water table is inclined slightly, so that gravity acceleration has a small component in the direction of motion, thus compensating for the effect of friction. Flow visualization leads to better understanding of the analogous system. Within the experimental errors, it is shown that the hydraulic analogy can be used as an effective tool for the study of two dimensional isentropic flows of gases in many fields.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.269-272
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• 2008

Internal flow field of supersonic nozzle with pintle, which control thrust of solid rocket motor, is very complicated by pintle tip shape and contour of nozzle. For studying of pintle nozzle performance by effects of internal flow field variation with pintle position, cold flow test and numerical analysis about needle type pintle shape were performed and results were presented in this paper. As the results of this study, three types of internal shocks exists in the pintle nozzle and oblique shock is oscillated by pintle position

• Journal of the Korean Society of Propulsion Engineers
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• 제11권2호
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• pp.26-36
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• 2007

The thermal response characteristics of nozzle liner for a solid rocket motor applying highly aluminized PCP or HTPB propellant with slotted tube grain have been investigated. The SEM photographs of aluminum oxide particles taken from nozzle liner show that the PCP propellant with the finer and less contents of oxidizer can offer greater possibility for increasing aluminum agglomeration than the HTPB propellant. The PCP propellant shows locally greater mechanical erosion at 4 circumferential areas of the nozzle entrance in line with grain slot due to the impingement of large particles, but the HTPB propellant shows greater thermochemical ablation at the nozzle blast tube, the throat insert and the exit cone because of relatively much more mole fraction of $H_2O\;and\;CO_2$ in combustion gases.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.651-663
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• 2017

Experimental results of $30^{\circ}-15^{\circ}$ nozzles were compared with numerically calculated convective heat transfer coefficients using FLUENT, Boundary Layer Integration Method and Bartz predictions. Also, the convective heat transfer coefficients were calculated by using FLUENT and boundary layer integration method for NASA HIPPO nozzles according to the characteristics of combustion gas and the correlation between pressure and pressure was compared. Finally, thermal analysis of NASA HIPPO nozzle was performed to compare the ablation thickness and char depth according to the combustion gas characteristics.