• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.87-93
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• 2016

In a Direct Connect(DC) mode altitude engine test, a labyrinth seal is set up between an air intake duct and an engine. The labyrinth seal plays a key role in mechanically isolating them, which contributes to the accurate measurement of thrust and the other component forces. However, when high vertical temperature gradient is generated in the supplied air in the duct, the isolation breaks down. In this paper, a labyrinth seal control device is designed and installed in an effort to eliminate the issue. Test result shows the device successfully gets rid of the contact problem even when high vertical temperature gradient is produced.

• 한국전산유체공학회:학술대회논문집
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• 2002.10a
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• pp.88-94
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• 2002

Curved intakes are commonly used from commercial aircraft to military missile. Sound radiation from the intake of air vehicle affects cabin noise, community noise and military detection. In this paper, Sound radiation from curved intake is computed using the high order, high resolution scheme. The generalized characteristic boundary conditions, adaptive nonlinear artificial dissipation model and conformal mapping for high order, high resolution scheme are used. The geometric change of curved intake and the frequency of acoustic source are considered. Two dimensional Euler equations are solved for theses analyses.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.713-721
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• 2004

Variable air intake and variable exhaust nozzle of hypersonic engines are designed and tested in this study. Dimensions for variable geometry air intake, ram combustor and variable geometry exhaust nozzle are defined based on the requirements of a pre-cooled turbojet engine. Hypersonic Ramjet Engine is designed as a scaled test bed for each component. Actuation forces of moving parts for variable intake and variable nozzle are reduced by balancing the other force in the opposite direction. A demonstrator engine which includes variable intake and variable nozzle is designed and the components are fabricated. Composite material with silicone carbide is applied for high temperature parts under oxidation environment such as leading edge of the variable intake and combustor liner. Internal cooling structure is adopted for both moving and static parts of the variable nozzle. Pressure recovery and mass capture ratio of the variable intake at Mach 5 is obtained by a hypersonic wind tunnel test. Flow characteristics of the variable nozzle are obtained by a low temperature flow test. Wall temperature and heat flux of the nozzle at Mach 3 is obtained by a firing test. As results, the intake and the nozzle are proved to be used at designed pressure and temperature environment.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.277-284
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• 2013

In this paper, the ventilating and heating system of T-103 trainer aircraft were investigated and redesigned to improve its poor performance. The ventilation system of the trainer was designed to increase the mass flow rate of fresh air by using air intake valves. The flow-in air through the air intake valve is supplied to the cabin by the ram effect of aircraft and the propeller. And the additional heating system was installed to improve the temperature of the cabin inside. The wasted heat from the exhaust gas of the engines was used as heat source of the additional heating system by installing an heat exchanger around the exhaust nozzle. The additional fresh air and the heated air enter the cabin via two ducts mounted under the instrument panel and behind the pedal in the cabin. The additional ventilating and heating system can be controlled by the first pilot and the secondary pilot individually using the control knob equipped separately. After mounting the additional ventilating and heating system, evaluations such as inspection of parts and component, ground run-up test, in-flight test, user test, etc. were conducted. The result of the tests was sufficient to meet the requirements of the manuals, and the pilots were satisfied with the additionally mounted systems.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.4
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• pp.15-24
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• 2014

This study conducted a computational fluid dynamics(CFD) analysis to find an appropriate diameter or sectional area of air ducts and fluid pipes which have an electromagnetic pulse(EMP) shied to protect indoor electronic devices in special buildings like military fortifications. The result shows that the optimized outdoor air intake size can be defined with either the ratio of the maximum air velocity in the supply duct to the air intake size, or the shape ratio of indoor supply diffuser to the outdoor air intake. In the case of water channel, the fluid velocity at EMP shield with the identical size of the pipe, decreases by 25% in average due to the resistance of the shield. The enlargement of diameter at the shield, 2 step, improves the fluid flow. It illustrated that the diameter of downstream pipe size is 1step larger than the upstream for providing the design flow rate. The shield increases friction and resistance, in the case of oil pipe, so the average flow velocity at the middle of the shield increase by 50% in average. In consideration of the fluid viscosity, the oil pipe should be enlarged 4 or 5 step from the typical design configuration. Therefore, the fluid channel size for air, water, and oil, should be reconsidered by the engineering approach when EMP shield is placed in the middle of channel.

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.579-584
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• 2005

Unsteady state free natural gas jets injected from several types of injectors were numerically simulated. Simulations showed good agreements with the schlieren experimental results. Moreover, injections of natural gas in intake manifolds of a single-valve engine and a double-valve engine were predicted as well. Predictions revealed that large volumetric injections of natural gas in intake manifolds led to strong impingement of natural gas with the intake valves, which as a result, gave rise to pronounced backward reflection of natural gas towards the inlets of intake manifolds, together with significant increase in pressure in intake manifold. Based on our simulations, we speculated that for engines with short intake manifolds, reflections of the mixture of natural gas and air were likely to approach the inlets of intake manifolds and subsequently be inbreathed into other cylinders, resulting in non-uniform mixture distributions between the cylinders. For engines with long intake manifolds, inasmuch as the degrees of intake interferences between the cylinders were not identical in light of the ignition sequences, non-uniform intake charge distributions between the cylinders would occur.

• 열병합발전
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• s.6
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• pp.13-20
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• 1998

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.283-290
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• 2007

Recently, plastic products in air-intake parts of automotive engines have become very popular due to advantages that include reduced weight, constricted cost, and lower intake air temperature. However, flow-induced noise in air-intake parts becomes a more serious problem for plastic intake-manifolds than for conventional aluminum-made manifolds. This is due to the fact that plastic manifolds transmit more noise owing to their lower material density. Internal aerodynamic noise from an Idle Speed control Actuator (ISA) is qualitatively analyzed by using a scaling law, which is expressed with some flow parameters such as pressure drop, maximum flow velocity, and turbulence kinetic energy. First, basic flow characteristics through ISA passage are identified with the flow predictions obtained by applying Computational Fluid Dynamics techniques. Then, the effects on ISA passage noise of each design factors including the duct turning shape and vane geometries are assessed. Based on these results, the preliminary low noise design for the ISA passage are proposed. The current method for the prediction of internal aerodynamic noise consists of the steady CFD and the scaling laws for the noise prediction. This combination is most cost-effective, compared with other methods, and therefore is believed to be suited for the preliminary design tool in the industrial field.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.8
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• pp.683-692
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• 2007

Recently, plastic products in air-intake parts of automotive engines have become very popular due to advantages that include reduced weight, constricted cost, and lower intake air temperature. However, flow-induced noise in air-intake parts becomes a more serious problem for plastic intake-manifolds than for conventional aluminum-made manifolds. This is due to the fact that plastic manifolds transmit more noise owing to their lower material density. Internal aerodynamic noise from an idle speed control actuator(ISA) is qualitatively analyzed by using a scaling law, which is expressed with some flow parameters such as pressure drop, maximum flow velocity, and turbulence kinetic energy. First, basic flow characteristics through ISA passage are identified with the flow predictions obtained by applying computational fluid dynamics techniques. Then, the effects on ISA passage noise of each design factors including the duct turning shape and vane geometries are assessed. Based on these results, the preliminary low noise design for the ISA passage are proposed. The current method for the prediction of internal aerodynamic noise consists of the steady CFD and the scaling laws for the noise prediction. This combination is most cost-effective, compared with other methods, and therefore is believed to be suited for the preliminary design tool in the industrial field.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.191-198
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• 1998

In this study, the effects of water vapor in inlet air, spark advance and fuel type in the spark ignition engine were investigated through the experiments of combustion and flame arriving pattern analysis using ionization probe. The results of flame propagation experiment using ionization probe show that the flame which ignited from spark plug located at the center of the combustion chamber propagated faster in exhaust side than in intake side due to the mixture flow motion inducted into combustion chamber from intake tumble port at all conditions. And as the partial vapor pressure increased, the flame propagation became slower in all direction. Especially effects were greater for intake side than the exhaust side.