• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3398-3405
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• 2011

Vibration intensity (VI) method is used to reduce sound source generated from air-conditioning rotary compressor. Generally VI method is a good tool to find a sound source through vibration power flow. In this paper, the vibrations are measured by using the 3 uni-axial accelerometer from both the shells of the normal compressor and the fault compressor. The VI method successfully found out the sound source position on the surface of the compressor. In addition, the main noise (3kHz ~ 6.3kHz) was deminished by applying the newly designed compressor inner part which is related to the orginal noise source.

• Journal of computational fluids engineering
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• v.2 no.2
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• pp.18-25
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• 1997

A pressure-based Navier-Stokes numerical solver was used to compare solutions of the k-ε/RNG k-ε turbulence models. An efficient grid generation scheme, the transient grid generation with full boundary control, was used to solve the flows in the tip clearance region. Results indicate that the calculations using k-ε model captures various phenomena related to the tip clearance with good accuracy.

• 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.40 no.2
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• pp.75-83
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• 2016

Since a turbomachine has complex flow characteristics, which are caused by adverse pressure gradient and high speed motion, an elaborate turbulence model is needed to accurately predict the flow. Some turbulence models such as an algebraic or a two-equation eddy viscosity model have been used for in-house RANS-code, but it is difficult to obtain good result for several complex flows. In this study, Durbin's V2-F turbulence model, which has been known for better prediction for severe flow separation, is applied to T-Flow. It was validated for simple cases such as channel and compressor cascade, and its applicability to turbomachinery was shown by analyzing internal flow of a single rotor. As a result, the V2-F turbulence model shows better blade surface pressure distribution than the one-and-two equation turbulence model.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.4
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• pp.23-32
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• 2012

The present study is aimed to develop an integrated performance analysis approach for the application of a compressor with variable inlet guide vane (VIGV) and vairable stator vane (VSV) in a small turbofan engine. For the integrated analysis approach, an engine performance analysis program, NPSS and a computer program used for predicting of axial flow compressor performance based on stage stacking method, STGSTK were linked with an optimisation package, Isight. This enables off-design performance analysis for the turbofan engine with VIGV and VSV hence provides the capability to predict stable operation condition of the engine with acceptable surge margin.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.141-146
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• 1999

The comming of high speed computers with large memory size in recent years has allowed the practical development of codes which solve the Reynolds-averaged NAvier-Stokes (RANS) equations in three dimensions. Such codes are already used by the large engine manufacturers for the advanced design of some engine components. Different computational fluid dynamics approaches and turbulence models exist, and it seems essential today to establish their degree of validity for application to typical configurations in turbomachinery. In 1993 the Turbomachinery Committee of the IGTI of ASME has issued an open invitation to predict the flow details of an isolated transonic fan rotor called as NASA ROTOR 37. This paper reports this test case.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.309-314
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• 1999

This paper is concerned with the viscous interaction between rotor and stator The viscous interaction is caused by wakes from upstream blades. The cascade was composed with five blades and cylinders were placed to make wakes and their location was about 50 percent of blade chord upstream. The location of cylinders were varied in the cascade axis with 0, 20, 40, 60 and 80 percent of pitch length. The velocity distribution in the cascade passage were measured using single slanted hot-wire and the ones in the boundary layer using boundary probe. As a result, wakes decay more rapidly at suction surface and more slowly at pressure surface. And the measurement of momentum thickness of cascade shows that the momentum thickness is larger near the blade surface. From measurement of blade boundary layer, turbulent intensity is also larger near the blade surface because wakes collide the boundary layer And wakes make boundary layer thickness smaller and delay flow separation.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.561-567
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• 2000

This paper is concerned with the viscous interaction between rotor and stator. The viscous interaction is caused by wakes from upstream blades. The rotor cascade in the experiment was composed with five blades, and cylinders were placed to make the stator wakes and their locations were about 50 percent upstream of blade chord. The locations of cylinders were varied in the direction of cascade axis with 0, 12.5, 25, 50, and 75 percent of pitch length. The static pressure distributions on the blade surfaces and the velocity distributions in the cascade flow were measured. From the experimental result it was found that the value of velocity defect by a cylinder wake might vary depending on the wake position within the cascade but the value at the cascade exit approached to some constant value regardless of the difference of wake locus. The momentum defect at the downstream from the cascade and the pressure distribution on the blade surfaces showed that the wake flowing near the blade surfaces caused the decrease of lift and the increase of drag regardless of the disappearance of flow separation.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.157-160
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• 2006

A turbo-expander is developed for the regeneration in the expansion process. The turbo-expander operates in the partial admission and supersonic flow, and an axial-type single stage turbine is applied to the turbo-expander. Its outer diameter is 82mm and the operating gas is R134a. A 15kW reciprocating compressor is applied in this experiment and the turbo-expander is installed in the expansion process instead of the commonly using expansion valve. Two supersonic nozzles are applied for the expansion process. The high speed of R 134a after passing the supersonic nozzles gives the impulse force to the turbo-expander and some powers are generated on this process. A generator is installed at the end of the turbo-expander shaft. The generating output power from the turbo-expander is controlled by the power controller. Pressures and temperatures are measured on the lines for the performance investigation. More than 600W/(kg/sec) are generated in this experiment.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.229-240
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• 1991

The large camber angle theory of turbomachine blade of compressor has been developed recently for the two-dimensional flow by Hawthorn, et al. However, in the above theory it was assumed that the fluid was incompressible and inviscid, and the blades had no thickness. In this study, the flow in a blade cascade being mounted in parallel fashion with blade of arbitrary thickness is studied in order to determine the effects of the camber angle on the performance characteristic of the blade section under the consideration of compressibility and viscosity of fluid. The panel method is used for potential flow analysis. The flow in the boundary-layer is obtained by solving the integral boundary-layer structure through the laminar, transitional , and turbulent flow using the pressure field determined from the potential flow. And then the viscous-inviscid interaction scheme is used for interaction of these two flows. For the determination of the variation in the outlet fluid angle influenced by deviation in cascade flow, the superposition method which is used for single foil is introduced in this analysis. By the introduction of this method, the effects of the deviation on outlet fluid angle and the resulting fluid angle are made to adjust for oneself through the calculation. As the result of this study, the blade of large camber angle, large incidence angle, large pitch-chord ratio has large viscous and compressible effect than those of small camber angle. Lift force increase as camber angle increases, but above 60.deg. of camber angle, lift force decrease as camber angle increases. But drag force increases linearly with camber angle increases in the entire region.