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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Propulsion Engineers
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Journal DOI :
The Korean Society of Propulsion Engineers
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Volume & Issues
Volume 3, Issue 4 - Dec 1999
Volume 3, Issue 3 - Sep 1999
Volume 3, Issue 2 - Jun 1999
Volume 3, Issue 1 - Mar 1999
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Analysis of Turbulent flow using Pressure Gradient Method
Journal of the Korean Society of Propulsion Engineers, volume 3, issue 2, 1999, Pages 1~9
Applicability of the pressure gradient method which is formulated based on pressure gradient is verified against turbulent flow analysis. In the pressure gradient method, pressure gradient instead of pressure itself is obtained using continuity constraint. Since correct pressure gradient is found only when mass conservation is satisfied, pressure gradient method can reflect physics of flow field properly The pressure gradient method is formulated with semi-staggered grid system which locates each primitive variables on the same grid point but evaluates pressure gradient in-between. This grid system ensures easy programming and reflection of correct physics in analysis. For verifying applicability of this method, the pressure gradient method is applied to turbulent flow analysis with low Reynolds number
model. Turbulent flows include fully developed channel flow, backward-facing step flow, and conical diffuser flow. Prediction results show that the pressure gradient method can be applied to turbulent flow analysis. However, the pressure gradient method requires somewhat long computation time. Proper way to find optimum under-relaxation factor,
, is also need to be developed.
Stability Analysis of Reacting Mixing Layers with Density Gradient and Wake Deficit
Journal of the Korean Society of Propulsion Engineers, volume 3, issue 2, 1999, Pages 10~17
This paper investigates the linear stability of both uniform and non-uniform density plane mixing layers with special emphasis on the effect of the wake component in the velocity profile. Velocity and density profiles for laminar flows are obtained from analytic profiles. Mixing layers with wakes have two generalized inflection points and two unstable modes-sinuous and varicose modes. For uniform density mixing layers, sinuous modes are more unstable than varicose modes, which shows wakes will be destabilized by sinuous modes. For non-uniform density mixing layers with high density in high speed flows, sinuous modes are more unstable than varicose modes. For non-uniform density mixing layers with high density in low speed flows, varicose modes can be more unstable than sinuous modes.
Analysis of Three Dimensional Liquid Ramjet Engine with Spray and Combustion
Journal of the Korean Society of Propulsion Engineers, volume 3, issue 2, 1999, Pages 18~24
Liquid ramjet combustor is closely connected with complex phenomena due to a series of processes such as intake air, spray, mixing, and combustion. The present numerical experiments were peformed to investigate these flow characteristics for two and three dimensional liquid ramjet combustor. Grid system was made with three domains: intake region where air is supplied and fuel is injected, combustor and nozzle region, and exit atmosphere region. The numerical results showed that two and three dimensional flow patterns in recirculation region of combustor were significantly different each other and spray model was necessary to predict correctly the chemical reaction flow characteristics. Numerically examined for two different location of fuel injector, one is located on the bottom position of curved intake and the other is located on the top position. We found that bottom position of fuel injector is better than top position because fuel influx to the recirculation region which is need to sustain chemical reaction is more than the latter.
A Study on Characterization of Hole Quality Effect on Composite Laminate Strength Reduction
Journal of the Korean Society of Propulsion Engineers, volume 3, issue 2, 1999, Pages 25~36
The main objectives of this research are to experimently explain the drilling mechanism for the production of bad holes and good holes during the drilling operation, to investigate how a wide range of drilling parameter affect composite laminate strength reduction, and to find which type of test provides the greatest interrogation of notched composite laminates. To achieve these objectives, a bulk of test specimens have been drilled with 5 different drilling parameters and tested with compressive, tensile, and flexural loads. It was found that the drilling parameters had a measurable effect on specimen hole quality as measured by static strength. The specimens, which were well supported, which had the higher spindle speed and lower feed rate, and which were well clamped gave the best hole qualities. The flexural test results presented the most clear and consistent failure strengths relating to the drilling parameters and associated hole quality.
Two-dimensional Thermal Analysis for Carbonacious Thermal Liner of Rocket Nozzle with Ablation and In-depth Pyrolysis
Journal of the Korean Society of Propulsion Engineers, volume 3, issue 2, 1999, Pages 37~47
This paper describes the thermal analysis which can calculate the ablation depth and temperature distribution of the rocket nozzle liner allowing geometry change caused by the ablation of nozzle liner. In this analysis, Zvyagin's model is used for surface ablation and Yaroslavtseva's model for in-depth pyrolysis. A deforming finite-element grid is used to account for external-boundary movement due to the erosion of thermal liner. The accuracy of the present numerical method is evaluated with a rocket nozzle liner and the numerical solutions are favorably agreed with experimental data. The temporal variations of temperature and ablation depth at the thermal liner of another rocket nozzle are numerically simulated and the results are discussed. Special emphasis is given to the effects of kinetic constants for carbon-carbon and carbon-phenolic composites on the ablation depth of thermal liner.
Performance Analysis of a 50㎾ Turbo-Generator Gas Turbine Engine with a Recuperator
Journal of the Korean Society of Propulsion Engineers, volume 3, issue 2, 1999, Pages 48~55
Performance analysis of a 50KW turbo-generator gas turbine engine with a recuperator was studied. Recuperated cycle has been employed to meet maximum fuel economy and ultra low emissions especially for military and vehicular engines. From thermodynamic stand point, it is known that recuperative cycle can contribute most to enhance thermal cycle efficiency for the Pressure ratios under 10 and of comparatively low turbine inlet temperature. Efficiency of a simple cycle with a recuperator increases relatively about 30% than without one at effectiveness of 0.5. Pressure losses in the heat exchanger less than 5.2% is considered in the design process. A tubular type heat exchanger is selected for this particular engine because it can provide simple construction as well as structural sturdiness and excellent leak tightness.
Experimental Investigation on Relationship of Winding Process Variables and Mechanical Properties for Filament Wound Composites
Journal of the Korean Society of Propulsion Engineers, volume 3, issue 2, 1999, Pages 56~65
The relationship of the winding process variables and the mechanical properties of filament wound composites is investigated experimentally. The winding process variables considered are the fiber tensions and the fiber ends. The filament wound ring specimens are fabricated using 3-axis controlled filament winding machine. Two types of carbon fibers, TZ-507 and IZ-40, are used as reinforcements and epoxy for filament winding is used as resin. During the winding process, the fiber tensions are varied from 0.5kgf to 3.0kgf, and the number of the fiber ends are varied from 1 to 6. The fiber volume fractions and the void contents for the ring specimens are measured through the resin digestion. The mechanical properties of the ring specimens are also evaluated by the split disk test. The test results show that the winding process variables affect the fiber volume fractions and the void contents of the ring specimens, which result in the variation of the tensile properties of the ring specimens. Therefore, suitable winding process variables should be applied to maximize the structural performance and the productivity for filament wound structures.
An Experimental Study for the Heat Transfer Augmentation of an Impinging Jet
Journal of the Korean Society of Propulsion Engineers, volume 3, issue 2, 1999, Pages 66~74
In this study, the heat transfer augmentation without additional blower power was obtained by using punched plate. Though this scheme has some disadvantages such as decrease of momentum caused by the punched plate, it has significantly increased heat transfer coefficients in the stagnation region. Compared with the case of no punched plate, heat transfer coefficients were increased by punched plate more than 2 times near the optimum condition determined in this study. Liquid crystal and hue-capturing technique were used in this study to obtain heat transfer coefficients.
Performance Analysis of a Cold Inert Gas Generator
Journal of the Korean Society of Propulsion Engineers, volume 3, issue 2, 1999, Pages 75~81
Present study deals with performance analysis of a cold inert gas generator which is to be used as an effective and prompt mean to suppress the fire. Every year, squandering of numerous People and assets by fire have been noticed around us. However, there seemed not enough progresses made to suppress the fire effectively for the past few centuries. Present study introduces CIGG(Cold Inert Gas Generator), basically a new conceptual approach to suppress the fire, through performance analysis of the machine and tried to suggest basic specifications of the heat exchanger which is a vital part of the machine, while at the same time, revealing the basic performance of the CIGG in the form of a design point.
The Formation of Detonation Wave and Acceleration Characteristics with the Ram Accelerator Projectile Shapes
Journal of the Korean Society of Propulsion Engineers, volume 3, issue 2, 1999, Pages 82~91
Projectile shapes of the superdetonative ram accelerator have great effects on shock structures, detonation wave formation, and ram acceleration characteristics. In this study, cone-cylinder-cone, a baseline projectile configuration of the superdetonative combustion mode, double-cone configurations and power-law shape, have been numerically investigated to analyze the effect of the front/rear configuration changes, on the flow field around the projectile, detonation wave formation process, and projectile acceleration characteristics. Hence, a ram projectile configuration with conspicuously improved acceleration characteristics has been proposed by adjusting the double cone angle and height. The results provide useful information for the ram accelerator design optimization study.