• 월간산업보건
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• s.79
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• pp.34-35
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• 1994

• Journal of Periodontal and Implant Science
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• v.39 no.1
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• pp.109-109
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• 2009

• 대한정형외과스포츠의학회:학술대회논문집
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• 2005.11a
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• pp.30-31
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• 2005

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.2
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• pp.280-287
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• 2000

Laboratory measurements were made of wall pressure fluctuations in a separated and reattaching flow over a backward-facing step. An array of 32 microphones along the streamwise direction was utilized. Various statistical properties of pressure fluctuations were scrutinized. The main emphasis was placed on the flow inhomogeneity along the streamwise direction. One point statistics such as the streamwise distribution of rms pressure and autospectra were shown to be generally consistent with other studies. The coherences and wavenumber spectra in the streamwise directions were indicative of the presence of dual modes in pressure; one is the large-scale vortical structure in low frequency and the other is the boundary-layer-like decaying mode in high frequency.

• Journal of computational fluids engineering
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• v.9 no.1
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• pp.10-17
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• 2004

Comprehensive investigation according to the two kinds of blades is systematically carried out for a design of the centrifugal blower. The motivation of this work is due to demand of enhanced flow rate with higher inlet pressure, such as air purifiers adopting several filters. It is observed that flow rate of the blower with forward blades is larger than that of the system with backward blades. The reason is due to larger outlet velocity from the rotating forward blades and the tendency is validated by a parallel experiment with a wind tunnel. Numerical analysis for the blower system shows detail information between the blades and inside the casing. A series of figures to show the flow details offers deep understanding of a centrifugal blower with the two different blades.

• The KSFM Journal of Fluid Machinery
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• v.16 no.2
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• pp.48-53
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• 2013

This paper presents a numerical investigation of the influence of the blade back sweep angle on the performance and flow characteristics in a centrifugal compressor with a vaneless diffuser. Five impellers with different back sweep angles were tested in the flow simulations. It was found that a low back sweep angle could improve the total-to-total pressure ratio and the work coefficient over whole operating ranges. However, the flow field in an impeller with a low back sweep angle produced a more non-uniform velocity distribution at the impeller exit because the wake region was significantly increased. As a consequence, the impeller with a low back sweep angle caused a low diffuser performance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.3039-3045
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• 1994

The k-$\varepsilon$ turbulence models by Launder et al.(1977, LPS) and Leschziner and Rodi(1981, LR) are modified to account for the secondary straining effect with having a generality in the present paper. The modified models are obtained by replacing the gradient Richardson number used to account for the secondary straining effect in the original models by a new parameter with a tensor-invariant correction form. These two modified models are used to predict the turbulent flow over a backward-facing step. In contrast to both standard and modified LR models, the modified LPS model is found to predict the reattachment point fairy well, as well as mean velocity, wall static pressure, turbulent kinetic energy and Reynolds shear stress in the recirculating region.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.1
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• pp.1-10
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• 1994

The flow and heat transfer characteristics behind a backward facing step located in a vertical channel has been studied. In this study, the numerical prediction has been performed by solving the Navier-Stokes equation and energy equation simultaneously with the SIMPLE algorithm embedied in TEACH code. Local heat flux was measured by using Schlieren Interferometer. The flow visualization was performed using the cylindrical lens and the laser beam that is scattered by the supplied glycerine particles. The velocity and temperature distributions, recirculation region, reattachment length, and local heat flux are obtained under the various parameters to investigate the buoyancy effect on the flow and heat transfer characteristics behind the step.

• 한국전산유체공학회:학술대회논문집
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• 1998.11a
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• pp.127-132
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• 1998

The present study is aimed to investigate flow characteristics of Two dimensional backward-facing step by numerical approach. A convection conservative difference scheme based upon SOLA algorithm is used for the solution of the two-dimensional incompressible Navier-Stokes equations to simulate the laminar, transitional and turbulent flow conditions at which the experimental data can be available for the backward-facing step. The twenty kinds of Reynolds number are used for the calculations. In an effort to demonstrate that the reported solutions are dependent on the mesh refinement, computations are performed on seven different meshes of uniformly increasing refinement. Also to investigate the result of inflow dependence, two kinds of the inflow profile are chosen for the laminar flow. As criterion of benchmarking the result of numerical simulation, reattachment length is used for the selected Reynolds numbers.

• Journal of Industrial Technology
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• v.19
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• pp.59-65
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• 1999

This study is to analyze turbulent flow over a backward-facing step in a rectangular duct. The side wall effects on the internal flow were determined by varying the aspect ratio(defined as the step span-to-height ratio) from 1 to 20. In the flow behind a backward-facing step, separation, recirculation and redeveloping is occurred frequently. These phenomena appear in a particular variation by varying the aspect ratio. The results show that the aspect ratio has an influence on the velocity and reattachment length. When the AR is increased, the reattachment length is increased. For 6 over aspect ration, the rate of increase is decreased. The length of recirculation in the upper corner is increased, as the increase of aspect ration. It's width is not changed in the variation of aspect ration. The transverse, streamwise and spanwise velocities were decreased along the flow down stream of the step.