• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.8
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• pp.1077-1084
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• 2000

In this work, a modified stage-stacking method for the performance prediction of multi-stage axial flow compressors is proposed. The method is based on a simultaneous calculation of all interstage variables (temperature, pressure, flow velocity) instead of the conventional sequential stage-by-stage scheme. The method is also very useful in simulating the effect of changing angles of the inlet guide vane and stator vanes on the compressor operating characteristics. Generalized stage performance curves are used in presenting the performance characteristics of each stage. General assumptions enable determination of flow path data and stage design performance. Performance of various real compressors is predicted and comparison between prediction and field data validates the usefulness of the present method.

• The KSFM Journal of Fluid Machinery
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• v.2 no.1 s.2
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• pp.88-95
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• 1999

This paper introduces the part of efforts to develop a derivative type turboshaft engine from an existing baseline engine for multi-purpose helicopters aiming at 4000 kg of take-off weight for 10-12 passengers. As a first step in meeting the development goal of increasing the output power from 720 hp to 840hp with minimum modification, a two stage axial compressor was redesigned to obtain the higher pressure ratio by removing the inlet guide vane and increasing the chord length. As a result, a two stage axial compressor was designed to facilitate a flow rate of 3.04 kg/s, a pressure ratio of 2.01 and an adiabatic efficiency of $85\%$. Its performance tests were carried out and verification of test results and redesign are under progress. Aerodynamic and structural analyses of the preliminary design are mainly described in this paper.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.713-716
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• 1998

To examine the influence of unsteady wake on the flow and heat transfer characteristics, an experiment has been conducted in a four-vane linear cascade. Flow and heat transfer measurements are made for the inlet Reynolds number of 66000(based on chord length and free-stream velocity). Turbulent intensity and stress were measured using hot wire anemometer, and to measure the convective heat transfer coefficients on the blade surfaces liquid crystal/gold film Intrex technique was used. The disturbance by the unsteady wake is characterized by the unresolved unsteadiness. The unsteady wake enhances the turbulent motion of flow in the cascade passage. It also promotes the boundary layer development and transition. The results show that heat transfer coefficients on the suction surface increase with increasing unresolved unsteadiness.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.3
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• pp.113-122
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• 1994

This paper describes the effects of combustion parameters on the characteristics of combustion products in swirling flow furnace. The concentration of combustion products and temperature distribution of flow field in the furnace have been investigated by numerical method. The fuel was injected into the furnace and the swirling device was constructed with three kinds of vane swirler at inlet port of furnace. The results of this study showed that the effect of combustion parameters on the concentration characteristics of carbon monoxide and nitrogen monoxide of combustion products. It was found that the pollutant formation wad dependent on the equivalence ratio and swirl intensity level.

• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1626-1637
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• 2006

The pressure pulsation due to the gear geometry of the gerotor (generalized rotor) pump mainly occurs in an instant that the chamber of the gerotor enters the delivery port and leaves the suction one. Such a pressure pulsation may result in undesirable vibration and noise of pump components as well as cavitation in hydraulic system. Therefore, it is very important to examine the pressure characteristic of the gerotor pump at its design and analysis stages. In this paper, in order to reduce the pressure pulsation in the gerotor pump, the port plate with the relief grooves is designed by referring to as notch of vane pump and relief groove of piston pump. A series of the theoretical analyses on the pressure pulsation is performed in consideration of various design parameters of the port plate, including the installation positions of the port inlet/outlet and the groove width, and the operating conditions such as rotational velocity and delivery pressure.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.1
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• pp.83-88
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• 2016

This paper describes the test results of plant minimum stable load (Pmin) for Ilijan Power Plant. The test was conducted on May 13 through 14, 2015 to investigate the plant operating and equipment condition in accordance with "Ilijan Plant Performance Test Procedure on Plant Minimum Stable Load" [1]. This paper also contains the assessment of the impact of Pmin to plant operating parameters and possible technical operating issues when operating at lower loads and to recommend the safe minimum load operation of Ilijan per block. In addition, this paper describes the performance calculation results of efficiency and heat rate depending on the load level.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.393-396
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• 1998

To examine the influence of unsteady wake on the flow and heat transfer characteristics, an experiment has been conducted in a four-vane linear cascade. Flow and heat transfer measurements are made for the inlet Reynolds number of 66000(based on chord length and free-stream velocity). Turbulent intensity and stress were measured using hot wire anemometer, and to measure the convective heat transfer coefficients on the blade surfaces liquid crystal/gold film Intrex technique was used. The disturbance by the unsteady wake is characterized by the unresolved unsteadiness. The unsteady wake enhances the turbulent motion of flow in the cascade passage. It also promotes the boundary layer development and transition. The results show that heat transfer coefficients on the suction surface increase with increasing unresolved unsteadiness.

• Solar Energy
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• v.17 no.2
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• pp.13-22
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• 1997

A study on the distribution characteristics of inflowed warm air is important to analyze warm air storage in a room. Also, in point of energy saving during heating, warm air flow characteristics occurred by circulation and distribution of inflowed warm air should be analyzed, and the storage efficiency should be considered in order to increase efficiency of heating system. For this study, in the real-sized model room, the temperature differences between inflowing warm air and inner room air are 10, 20, $30^{\circ}C$(3steps), and the flow rates of inflowing warm air are 0.5, 1, 2, 3m/s(4steps) respectively as dynamic parameters. Also, anemos and vane diffuser are used as inlet geometric condition. Consequently, on geometric conditions, high thermal storage efficiency can be obtained with the vane diffuser, and heat flow characteristics depend on the inflowing velocity more than reference temperature difference.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.446-456
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• 2006

The effect of relative position of the stationary turbine blade for the fixed vane has been investigated on blade tip and shroud heat transfer. The local mass transfer coefficients were measured on the tip and shroud fur the blade fixed at six different positions within a pitch. A low speed stationary annular cascade with a single turbine stage was used. The chord length of the tested blade is 150 mm and the mean tip clearance of the blade having flat tip is 2.5% of the blade chord. A naphthalene sublimation technique was used for the detailed mass transfer measurements on the tip and the shroud. The inlet flow Reynolds number based on chord length and incoming flow velocity is fixed to $1.5{\times}10^5$. The results show that the incoming flow condition and heat transfer characteristics significantly change when the relative position of the blade changes. On the tip, the size of high heat/mass transfer region along the pressure side varies in the axial direction and the difference of heat transfer coefficient is up to 40% in the upstream region of the tip because the position of flow reattachment changes. On shroud, the effect of tip leakage vortex on the shroud as well as tip gap entering flow changes as the blade position changes. Thus, significantly different heat transfer patterns are observed with various blade positions and the periodic variation of heat transfer is expected with the blade rotation.

• Journal of Aerospace System Engineering
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• v.14 no.3
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• pp.1-9
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• 2020

In this paper, the effects of the delta winglet vortex generator, the airfoil vortex generator and the guide vanes on the friction factor and the Colburn factor in the fin-tube flow were studied. The vortex generator and guide vane were non-dimensionalized based on the channel height and tube diameter, and locations were selected according to the authors' suggestions. The Reynolds number based on the inlet velocity and the tube diameter was selected in the range of 1400-8000. As a result, the friction factor resulted in a 4.7% decrease in guide vanes at the Reynolds number 8000 over the conventional fin-tube, and the Colburn factor resulted in a 33% increase in the delta winglet vortex generator at the Reynolds number 3800 over the conventional fin-tube.