• Proceedings of the KSME Conference
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• 2001.11b
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• pp.658-663
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• 2001

In this study, the axial-compressor design and performance/flow analysis program is developed. A mean-line analysis was used to determine optimum arrangement of overall geometry and its off-design performance is predicted by stage-stacking method. Three dimensional blade shape is generated using radial equilibrium equation and vortex methods. Various blade shape is generated and their performance is compared. Finally the quasi-three dimensional flow analysis is applied to investigate the detailed flow phenomena.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.10
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• pp.843-851
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• 2003

The present paper studies the leakage flow model used in the performance prediction of a scroll compressor. Two leakage flow models, isentropic and Fanno flow model, are studied in detail. Their predictions are also compared with CFD solutions to check the validity as a leakage flow model. Comparison with CFD solutions shows that the isentropic flow model predicts excessive leakage flow rate, while the Fanno flow model shows acceptable agreement with CFD solutions. The excessive leakage flow rate by isentropic flow model results in under-prediction of the overall performance of a scroll compressor.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.291-300
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• 1999

Currently under development is an airborne auxiliary power unit with 100 Kw equivalent power, which is composed of a centrifugal compressor, a reverse annular combustor, and a radial turbine. Air-foil bearings are used in this power unit to eliminate the oil supplying system, which can reduce the system complexity and weight. The high speed generator is adopted as an electric power generation and engine starting system, which can also eliminate the reduction gear system. Not only electric power but also pneumatic power is provided by bleeding the compressed air This power unit is aimed for the multi-purpose use such as a primary power unit In the army weapon system, an auxiliary power and environmental control unit in a next-generation tank, and a smoke generating unit.

• The KSFM Journal of Fluid Machinery
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• v.2 no.3 s.4
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• pp.17-23
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• 1999

In the present numerical analysis, investigation of the effect of blade loadings from design shape on the slip factor variation was studied. Both the Eckardt radial bladed impeller and the backswept impeller were analyzed. In addition, a new design of the blade profile was arbitrarily attempted to generate a center-loading pattern in the original backswept impeller. Three dimensional compressible Navier-Stokes flow analysis with the Baldwin-Lomax turbulence model was applied to get the numerical slip factor at each impeller exit plane using the mass-averaging technique. The numerical slip (actors are in good agreement with the experimental ones and the Wiesner's slip factors deviate further from the numerical and experimental ones in both backswept impellers. Deviation angles and meridional channel loadings are found in no relation with the trend of change of the slip factor. Blade-to-blade loadings in midspan location are, however, found to have a direct relationship, especially at the sections where maximum loadings we to be expected. That information can be utilized in establishing an improved expression for slip factors in the future.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.277-278
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• 2015

Korea Aerospace Research Institute(KARI) has developed the gas turbine core technologies since 1989 and has built the infrastructure for the development of gas turbine. Efficiency and flow instability are the major research object in radial and axial compressors. For combustor, NOx reduction is major research object. KARI also has developed turbine cooling technology as well as turbine aerodynamic technology.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.9
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• pp.1247-1254
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• 1998

The vaneless diffusers are widely used in industrial centrifugal compressors which are required to operate within a wide flow range. When very high pressure gases are handled by centrifugal compressor. rotating stall is a serious problem because of the occurance of large aerodynamic exciting forces. Rotating stall mostly often occurs in the impellers but it can occur in vaneless diffusers as well. In this experimental study, the rotating stall in vaneless diffuser with radial type centrifugal impeller was measured by changing the flow rate with I-type, X-type hotwire. As the result, it was cleared which type of rotating stall of the impeller stall would occur and how many stall cells would appear relating with the flow rate. As the flow rate reduced, the propagation speed of rotating stall was reduced. But the stall cell number unchanged with respect to the flow rate.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.4
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• pp.274-282
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• 2009

Diaphragm compressor is widely used for hydrogen compression because it achieves high gas pressure without gas contamination. Diaphragm deflecting in the cavity with high pressure formed by an oil compression is the most important component in the compressor. Therefore, it is necessary to obtain deflection degree of diaphragm to predict the damage point of diaphragm. The objective of this study is to estimate the diaphragm's damage point through diaphragm deflection test by implementing with strain gauges attached on several radial points. Without gas compression, strain sum of each points varied as similarly as the variation of the pressure with respect to time. And while the motor speed was slower than 400rpm, the strain near the rim was larger than that of the center. When motor speed, however, was over 500rpm, strain became similar to that of the center and the rim. With gas compression, it was shown that the variation of the strain sum was delayed against that of the pressure and the strain near the rim was much higher than that of the center.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.7
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• pp.759-766
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• 2011

Recently, noise reduction in room air conditioners has been one of the important issues as well as cooling efficiency. The rotary compressor is the dominant noise source in an air conditioner. A number of studies have been conducted on reducing compressor noise through improving muffler and resonator design. However the noise from the accumulator, a noise delivering path between compressor and air conditioner, is not fully taken into consideration. The accumulator contains a large inner cavity, and usually generates additional resonance noise during operation. This paper aims to conduct an optimal design for reducing accumulator noise by maximizing the transmission loss within the target frequency range that represents high-order nonlinearity. Design of experiments and radial basis function neural network are used in the context of approximate meta-models, and genetic algorithm is used as an optimization tool.

• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.2
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• pp.84-90
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• 1997

The turboshaft engine with the free power turbine has been used for various purposes, for instance electric power generator, emergency power source, helicopter powerplant and so on. Steady-state simulation program was developed and experimental tests was carried out for comparing with computer simulation results. The test unit was composed of 1-stage centrifugal compressor, the can type combustor chamber, 1-stage radial type compressor turbine, and radial type free power turbine, and its output power is obtained from 3-phase AC generator. Main component characteristics which was used for the steady state simulation program, were obtained from the manufacturer of the test unit, and modified from experimental results of test unit. In comparison between computer simulation and experimental test results even though the test unit has the operational limit, deviation of component performance characteristics in simulation were within 6％ range of experimental results.

• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.844-853
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• 2003

In this paper, a dynamic analysis of the reciprocating compression mechanism of a small refrigeration compressor is performed. In the problem formulation of the mechanism dynamics, the viscous frictional force between the piston and the cylinder wall is considered in order to determine the coupled dynamic behaviors of the piston and the crankshaft. Simultaneous solutions are obtained for the equations of motion of the reciprocating mechanism and the time-dependent Reynolds equations for the lubricating film between the piston and the cylinder wall and for the oil films on the journal bearings. The hydrodynamic forces of the journal bearings are calculated by using a finite bearing model along with the Gumbel boundary condition. A Newton-Raphson procedure is employed in solving the nonlinear equations for the piston and crankshaft. The developed computer program can be used to calculate the complete trajectories of the piston and the crankshaft as functions of the crank angle under compressor-running conditions. The results explored the effects of the radial clearance of the piston, oil viscosity, and mass and mass moment of inertia of the piston and connecting rod on the stability of the compression mechanism.