• Journal of ILASS-Korea
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• v.22 no.3
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• pp.116-121
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• 2017

Pre-combustion chamber type indirect diesel engines have different combustion characteristics compared with those of common rail direct injection engine. The CONVERGE, specific engine CFD program, was used to simulate hollow cone spray model and combustion. The air-fuel mixture flow propagating from pre-combustion chamber to cylinder was concentrated at top half and center of the pre-combustion chamber throat. Stronger mixture flow was formed at smaller and longer throat cases. As a result, thermal efficiency and fuel consumption were improved for modified throat shape and the soot emission was also reduced.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.392-396
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• 2012

Experimental and computational study for steady-state pintle driven nozzle throat flow are carried out by changing four pintle shape. Results show that thruster performance is influenced by pintle shape greatly. This attributes to the distorted throat area and chamber pressure change as the pintle shape and its penetration.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.10
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• pp.985-991
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• 2010

The objective of this work was to investigate the pintle-tip shape effect on nozzle flow and thrust by cold flow test. When nozzle throat area was decreased by pintle movement, chamber pressure was increased monotonously but thrust was increased differently according to every pintle-tip shape. At the same chamber pressure and nozzle throat area, thrust of convex pintle-tip shape was mostly larger than that of concave one. Nozzle wall pressure distribution and magnitude of pintle-tip load depended on the pintle-tip shape, pintle position and nozzle throat area.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.153-156
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• 2011

Steady state experiment was carried out for modulatable thruster applications, with four different pintles. Results show that thrust can be modulated by changing nozzle throat area with pintle penetration. However, effect of pintle shape on the thruster performance is yet to be concluded.

• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.51-55
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• 2003

In this research, authors tried to measure the shape of the nozzle throat of KL-3 engines, which is the main engine of KSR-III rocket, to find the increase of nozzle area caused by the thermal ablation. For the purpose, we invented an image-based method instead of the 3D pointer, which is actually inaccessible to such large scale engines. As a result, our equipment showed satisfactory accuracy and performance. Analysing the results of experiments, we find that the pattern of ablation is determined by the spray pattern and that the process of thermal ablation phenomena can be categorized in three regimes - the first regime that the shape of nozzle throat is maintained and ablation is negligible, the second regime that saw-tooth form is developed and ablation is accelerated, and the third regime that the saw-tooth form is already established and the growth of ablation rate is reduced. Also, we find that the ratio of area increase after 60 seconds combustion is +5.82% and conclude that this figure is acceptable and satisfactory.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.514-517
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• 2008

An hydraulic experiment was carried out in an open channel flume in order to investigate the water discharge capability of the sluice caisson for tidal power generation, which greatly affects the economical efficiency of the construction of a tidal power plant. To predict the influence of change in the major design parameters relating to the sluice shape on the water discharge capability of the sluice, the experiment was carried out very precisely. The experiment was carried out for the six different sluice models of different widths and bottom heights of the sluice throat section. The experimental data showed that the water discharge generally increased by increasing the width of the throat section if the side shape of the sluice was the same. In addition, the coefficient of discharge was larger when the bottom height of the throat section was higher for the two bottom heights that were tested.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.346-351
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• 2017

A numerical study has been conducted to investigate flow characteristics of STED with ram structure shape. By increasing the attack angle of shock cone, vacuum pressure is increased because of oblique shock at ram structure and separation point moved to the downstream of the second throat. By increasing blockage ratio, expansion wave angle is increased at ram structure while vacuum pressure is constant.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.1
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• pp.81-92
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• 2008

In this study, the analysis results were presented for the experimental data of sluice for tidal power generation that were installed in an open channel flume. The experiment was carried out for the six different sluice models of different widths and bottom heights of the sluice throat section. If the side shape of the sluice was the same, the coefficient of discharge generally increased by increasing the width of the throat section. However, when the water discharge was small and the upstream water level was low, the coefficient of discharge increased for a while but decreased later with the increase of the throat section width. In addition, the coefficient of discharge was larger when the bottom height of the throat section was higher, regardless of the width of the throat section. It was concluded that the values of coefficient of discharge that were frequently used in the previous feasibility studies were underestimated so that should be adjusted to higher values.

• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.153-162
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• 2002

This paper predicted the engineering constants of spatially reinforced carbon/ carbon composites and analyzed the mechanical behaviour of the kick motor nozzle. Those equivalent engineering constants are used to analyze the mechanical behaviour of the kick motor nozzle. Because the distribution of equivalent engineering constants is varying as change its structure, we made a program to predict engineering constants of spatially reinforced composites. The kick motor nozzle consists of graphite or spatially reinforced carbon/ carbon composites for the nozzle throat, carbon/ phenol for the nozzle entrance and the expansion part, and steel for the outer surface of the expansion part. The 4-D carbon/ carbon composite shows the smallest deformed shape of the nozzle throat, which has a favorable effect on the rocket thrust, and the most uniform deformation of all nozzle throat materials. In addition to analysis, ground firing tests of 4D C/ C nozzle throat and graphite nozzle throat were performed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.40-45
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• 2005

Techniques used for throcket motors are mainly classified as fixed nozzles with mechanical exhaust jet interferences on the expansion region (such as jet tabs and jet vanes) and movable nozzles(such as ball&socket md flexible seal). Using the numerical analysis and the cold-flow test, this paper evaluates the performance of supersonic nozzle for asymmetric entrance shape at tilted position of ball&socket nozzle. Numerical results show that the asymmetric effects in the flow fields are gradually diminished up to the nozzle throat and are not noticeable downstream of the nozzle throat. Although the calculated thrust and the lateral force are less than those of cold-flow test, two results show a flirty good agreement.