• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.497-500
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• 2011

The experimental study of thermal stress in the solid rocket engine nozzle with two different materials, SCM-440 and STS-630, was evaluated. SCM-440 has lager temperature increasing rate and higher temperature at the nozzle expansion region than STS-630. Thermal barrier efficiency and endurance of Zirconia coating were evaluated after making two more nozzles coated by Zirconica. Both coated materials showed about 70 percent higher thermal barrier efficiency than uncoated nozzles. Therefore, Zirconia coating using plasma spray method was useful in thermal safety at supersonic nozzle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.78-81
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• 2009

A series of hydraulic tests of a fuel pump are performed using water at a room temperature. The pump is under development for 75-ton class liquid rocket engines of the open-loop gas generator type. According to the test results, the fuel pump satisfies its design requirement and its head and efficiency at the design flowrate are higher than the expected value by the computational analysis. Also, it is found that the pressure at the rear bearing outlet is higher than expected because the inlet of bypass pipe line is narrow. Furthermore, the flowrate of the secondary flow is estimated using the pressure difference of the elbow of the bypass pipe line.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.511-514
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• 2009

In this study, the combustion characteristics of hybrid rocket fuel with tapered grain port were studied. The regression rate was increased about 17.5% by using the convergence port shape fuel. On the other hand, in case of divergence port shape fuel, any notable difference of regression rate was not observed when compared with regression rate of the cylindrical port shape fuel. Also, in case of convergence port shape fuel, characteristic velocity efficiency was increased. From these results, one can notice that convergence port shape of hybrid rocket fuel can be effective configuration in terms of improvement of combustion efficiency and performance.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.3
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• pp.25-30
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• 1999

An experimental investigation was conducted to explore the effects of air mass flux on the combustion efficiency and particle size distributions in a solid fuel ramjet using a fuel grain highly loaded with boron carbide. Particle distributions were measured at the grain exit and at the nozz1e entrance using a Malvern 2600 HSD. Combustion efficiency increased with decreasing air mass flux. In general, the particle distribution was trimodal or quadrimodal with node peaks at approximately 4, 15, and 25$\mu\textrm{m}$ and possibly one at less than 2$\mu\textrm{m}$. The larger particles were the result of surface agglomeration, primarily within the recirculation region. Higher inlet air temperature produced higher combustion efficiencies, apparently the result of enhanced combustion of the larger boron carbide particles that burn in a diffusion controlled regime.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.2
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• pp.36-43
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• 2011

The present study deals with numerical flow analysis to investigate the effect of sweep and lean on the performance characteristics of a partial admission supersonic turbine. The flow analysis was performed for three different angles. The angles of sweep and lean are $5^{\circ}$, $10^{\circ}$, $15^{\circ}$. The results of the flow analysis showed that the efficiency is improved as the sweep angle is increased. However, a sweep angle of $5^{\circ}$ was less effective in comparison with the baseline model. The total pressure loss was reduced as the lean angle is increased, but the total to static efficiency was decreased.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.4
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• pp.266-274
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• 2016

Many researchers have been trying to improve the propulsion efficiency of a propeller. In this study, the numerical analysis is carried out for the POW(Propeller Open Water test) performance of a propeller equipped with an energy saving device called PHVC(Propeller Hub Vortex Control). PHVC is aimed to control the propeller hub vortex behind the propeller so that the rotational kinetic energy loss can be reduced. The unsteady Reynolds Averaged Navier-Stokes(URANS) equations are assumed as the governing flow equations and are solved by using a commercial CFD(Computational Fluid Dynamics) software, where SST k-ω model is selected for turbulence closure. The computed characteristic values, thrust, torque and propulsion efficiency coefficients for the target propeller with and without PHVC and the local flows in the propeller wake region are validated by the model test results of KRISO LCT(Large Cavitation Tunnel). It is concluded from the present numerical results that CFD can be a good promising method in the assessment of the hydrodynamic performance of PHVC in the design stage.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.37-46
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• 2007

In this study, combustion fields of the end-burning hybrid combustor with tangential oxidizer injectors are examined. Momentum ratio of oxidizer is used as a main parameter to analyse the combustion efficiency with temperature, pressure, swirl velocity and mixture fraction field. It was found that as momentum ratio decreases the overall combustion efficiency is enhanced with the pressure field being insensitive to momentum ratio keeping quasi-uniform distribution. Irrespective to the momentum ratio, annular hot region commonly occurred in the upper combustion chamber where this phenomenon was left for a future improvement to be followed.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.4
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• pp.41-47
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• 2011

Turbopump, which is a part of 75 ton open cycle liquid rocket engine has a super sonic impulse turbine. This paper investigated the leading edge thickness effect on the turbine performance experimently. Two rotors were tested with the different leading edge thickness. The ratios (rotor thickness to Pitch) are 1.9 and 1.4 times to 30 ton turbine rotor. As a result, a rotor with 1.4 times ratio had a 1.5% higher efficiency gain than a rotor with 1.9 times ratio. The pressure ratio with the maximum efficiency on the same rotational speed was increased to the full expansion ratio of nozzle.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.6
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• pp.38-45
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• 2016

A study was conducted on the effect of leading edge location for the performance characteristics of a centrifugal compressor impeller. Five impellers with different leading edge location were selected for numerical analysis. The impeller with leading edge located 10% away from the inlet about meridional distance from entrance to exit showed the best total pressure ratio and efficiency. Also, this case showed relatively uniform flow distribution because of a weak intensity of the separation region at impeller exit. The impeller with leading edge located far from this location showed lowest total pressure ratio and efficiency. Performance of compressor also decreased due to non-uniform flow distribution at impeller exit.

• Journal of the Korean Society for Railway
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• v.19 no.5
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• pp.600-608
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• 2016

This paper will describe the optimal design of an induction motor for the propulsion of an electric railway. First, the design requirements are satisfied through the basic model, which is designed in a design process using the equivalent circuit. Then, Rotor slot and Airgap are determined by analysis and comparison of torque, torque ripple, efficiency, and power factor. In addition, Rotor slot shape is optimized by using the response surface method. Finally, through the results of equivalent circuit and FEA, the final model is found to satisfy the design requirements; its efficiency was far higher than that of the basic model.