• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1229-1239
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• 1999

A computational study on unsteady compressible flows has been performed by adopting a low Reynolds number $k-{\omega}$ turbulence model in conjunction with dual time stepping scheme. An explicit four-stage Runge-Kutta scheme for the Navier-Stokes equations and an approximate factorization scheme for the $k-{\omega}$ turbulence model equations are used. Computational results obtained for blade surface pressure distributions in the process of rotor-stator interaction in a turbine stage are in good agreement with extant experimental data. The effects of the wake from the stator on the boundary-layer transition over the rotor blade surface are discussed by showing that high intensity turbulence of the stator wake induces an early transition.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.475-480
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• 2001

The flowfield of transverse jet in a supersonic air stream subjected to shock wave turbulent boundary layer interactions is simulated numerically by Generalized Taylor Galerkin(GTG) finite element methods. Effects of turbulence are taken into account with a two-equation $(k-\varepsilon)$ model with a compressibility correction. Injection pressures and slot widths are varied in the present study. Pressure, separation extents, and penetration heights are compared with experimental data. Favorable comparisons with experimental measurements are demonstrated.

• Journal of the Korean Society of Visualization
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• v.5 no.2
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• pp.56-63
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• 2007

Flow visualization and aerodynamic characteristics of delta wings with two different leading edge geometries are investigated by PIV system and wind tunnel balance when the Reynolds number is about based on the freestream velocity and the root chord length. Delta wing models have 65-deg swept angle, and the leading edge shapes are divided into round- and sharp- type. The experimental results indicated that the leading-edge vortex strength and aerodynamic coefficient in the round leading edge are stronger and more, respectively than those in the sharp one. Therefore the flow interactions between vortices and the boundary layer are more desirable or more rapidly swirled in the round-type leading edge.

• International Journal of Aeronautical and Space Sciences
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• v.5 no.2
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• pp.9-17
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• 2004

In this paper, a small supersonic wind tunnel was designed and built to studythe flow characteristics of a supersonic impulse turbine cascade by experiment. Theflow was visualized by means of a single pass Schlieren system. The supersoniccascade with 3-dimensional supersonic nozzle was tested over a wide range ofpressure ratio. Highly complicated flow patterns including shocks, nozzle-cascadeinteraction and shock boundary layer interactions were observed.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1732-1737
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• 2004

In this paper, a small supersonic wind tunnel is designed and built to study the flow characteristics of a supersonic impulse turbine cascade. The flow is visualized by means of a single pass Schlieren system. The supersonic cascade with 3-dimensional supersonic nozzle was tested over a wide range of nozzle installation angle. Highly complicated flow patterns including shocks, nozzle-cascade interaction and shock boundary layer interactions are observed.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.1-8
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• 2004

In this paper, a small supersonic wind tunnel is designed and built to study the flow characteristics of a supersonic impulse turbine cascade. The flow is visualized by means of a sin91e pass Schlieren system. The supersonic cascade with 3-dimensional supersonic nozzle was tested over a wide range of nozzle installation angle. Highly complicated flow patterns including shocks, nozzle-cascade interaction and shock boundary layer interactions are observed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.807-812
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• 2004

In this paper, a small supersonic wind tunnel was designed and built to study the flow characteristics of a supersonic impulse turbine cascade by experiment. The flow was visualized by means of a single pass Schlieren system. The supersonic cascade with 3-dimensional supersonic nozzle was tested over a wide range of pressure ratio. Highly complicated flow patterns including shocks, nozzle-cascade interaction and shock boundary layer interactions were observed.

• Journal of Ocean Engineering and Technology
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• v.8 no.2
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• pp.31-37
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• 1994

3-Dimensional panel method is now developed to the level that one can calculate the lift of a three dimensional body with the same accuracy of wind tunnel test and some current codes can consider the boundary layer effects due to the viscosity and unsteady motion in the calculation of lift. This paper is also aimed to develop these kinds of computing programs, and as a beginning, the authors restricted the problems to the steady potential flow cases. The calculation of 3-Dimensional body, wing and tandem wing carried out, using source panel and vortex ring panel. Finally, the interactions between 3-Dimension symmetric body and a wing are also calculated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.99-108
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• 2004

In this paper, a small supersonic wind tunnel is designed and built to study the flow characteristics of a supersonic impulse turbine. The flow is visualized by means of a single pass Schlieren system. The supersonic cascade with 2-dimensional supersonic nozzle was tested over a wide range of pressure ratio. Highly complicated flow patterns including shocks, nozzle-cascade interaction and shock boundary layer interactions are observed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.1
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• pp.92-100
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• 2018

Vortical systems are considered a main feature to sustain turbulence in a boundary layer through interaction. Such turbulent structures result in frictional drag and erosion or vibration in engineering applications. Research for controlling turbulent flow has been actively carried out, but in order to show the effect of vortices in a turbulent boundary layer, it is necessary to clarify the mechanism by which turbulent energy is transferred. For this purpose, it is convenient to demonstrate and capture phenomena in a laminar boundary layer. Therefore, in this study, the interactions of disturbed flow around a hemisphere on a flat plate in laminar flow were analyzed. In other words, a street of hairpin vortices was generated following a wake region formed after flow separation occurred over a hemisphere. Necklace vortices surrounding the hemisphere also appeared due to a strong adverse pressure gradient that brought high momentum fluid into the wake region thereby leading to an increase in the frequency of hairpin vortices. To mitigate the effect of these necklace vortices, local suction control was applied through a hole in front of the hemisphere. Flow visualization was recorded to qualitatively determine flow modifications, and hot-film measurements quantitatively supported conclusions on how much the power of the hairpin vortices was reduced by local wall suction.