• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2023-2028
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• 2008

In present study, the flow field near the fin surface of plate fin - oval tube heat exchanger with delta wing vortex generator was numerically analyzed. As results, the well developed vortex behind delta wing was observed. These vortex can improve heat transfer fin surface behind delta wing vortex generators.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.2
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• pp.98-106
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• 2007

The vortex flow characteristics of a double-delta wing, which can change the incidence angle of its apex strake was investigated through the wing-surface pressure measurement and the particle image velocimetry(PIV) measurement of the wing-leeward flow region. The apex strake has sharp edges and can change its incidence angle with a hinge line at the 23% chord position measured from the apex of the main wing. The present study revealed that the incidence-angle change of the apex strake could greatly alter the vortex flow pattern around the double-delta wing and the wing-surface pressure distribution, which suggested that the apex strake could be used as an effective device for the active control of delta-wing vortex flow.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.2
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• pp.128-136
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• 2006

The present study examined the effects of micro leading-edge flaps on the vortex characteristic changes of a double-delta wing through pressure measurements of the wing upper surface and PIV measurements of the wing-leeward flow region. The experimental data were collected and analyzed while changing the deflection angle of the leading-edge flaps to investigate the feasibility of using micro leading-edge flaps as flow control devices. The test results revealed that the leading edge modification could greatly alter the vortex flow pattern and the wing surface pressure of the delta wing, which suggested that the leading-edge flaps could be used as an effective device for the control of delta-wing vortex flow.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.795-798
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• 2002

This paper dispicts the vortical flow characteristics over a delta wing using a computational analysis for the purpose of investigating and visualizing the effect of the angle of attack and fee stream velocity on the low-speed delta wing aerodynamics. Computations are applied to the full, 3-dimensional, compressible, Navier-Stokes Equations. In computations, the free stream velocity is changed between 20m/s and 60m/s and the angle of attack of the delta wing is changed between $16^{\circ}\;and\;28^{\circ}$. For the correct prediction of the major features associated with the delta wing vortex flows, various turbulence models are tested. The standard $k-{\varepsilon}$ turbulence model predict well the vertical flows over the delta wing. Computational results are compared with the previous experimental ones. It is found that the present CFD results predict the vortical flow characteristics over the delta wing, and with an increase in the free steam velocity, the leading edge vortex moves outboard and its streangth is increased.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.215-224
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• 2001

An experimental investigation was conducted on the interaction of vortices over a delta wing with the leading edge extension for three angles of attack($16^{\circ},\; 24^{\circ} \;and\; 28^{\circ}$) at Reynolds number of $1.76{\times}10^6.$ The experimental data included total pressure contours and velocity vectors using 5-hole probe measurements. Constant total pressure coefficient contours show the LEX vortex moves downward and outboard, while the wing vortex exhibited an inboard and upward migration. At near the trailing edge, these vortices reveal a direct interaction between the wing and LEX vortex, featuring a coiling of vortex cores about each other. The combined effect of the interaction of these two vortices and proximity to the wing surface results in the increase of the suction peak. This is in contrast to the result obtained on the delta wing alone configuration, where the effect of the vortex breakdown was manifested. The interaction of the wing and LEX vortices is more pronounced at higher AOA.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.3
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• pp.77-86
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• 2002

An experimental study of the vortex interaction characteristics of a delta wing/LEX configuration was conducted in a wind tunnel using the micro water droplet and laser beam sheet visualization technique. The main focus of this study was to analyze the effect of the angle of attack and sideslip angle on the vortex interaction and vortex breakdown. These tests were accomplished at angles of attack between $16^{\circ}$ and $28^{\circ}$ and sideslip angle between $0^{\circ}$ and $-15^{\circ}$ at free-stream velocity of 6.2 m/s. Flow visualization data provide a description of the vortex interaction between LEX and wing vortices, and of the vortex breakdown. The introduction of LEX vortex stabilized the vortical flow, and delayed the vortex breakdown up to higher angle of attack. The vortex interaction and breakdown was promoted on the windward side, whereas they are suppressed on the leeward side.

• Journal of the Korean Society of Visualization
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• v.2 no.2
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• pp.52-57
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• 2004

The development and interaction of vortices over a delta wing with leading edge extension (LEX) was investigated through off-surface flow visualization using micro water droplets and a laser beam sheet. Angles of attack of $20^{\circ}$ and 24$^{\circ}$ were tested at sideslip angles of $0^{\circ}$, $-5^{\circ}$, and $-10^{\circ}$ The flow Reynolds number based on the main-wing root chord was $1.82{\times}10^{5}$. The wing vortex and the LEX vortex coiled around each other while maintaining comparable strength and identity at a zero sideslip. The increase of angle of attack intensified the coiling and shifted the cores of the wing and LEX vortices inboard and upward. By sideslip, the coiling, the merging and the diffusion of the wing and LEX vortices were increased on the windward side, whereas they were delayed significantly on the leeward side. The present study confirmed that the sideslip angle had a profound effect on the vortex structure and interaction of a delta wing with LEX, which characterized the vortex-induced aerodynamic load.

• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.914-924
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• 2003

The interaction and breakdown of vortices over the Leading Edge Extension (LEX) - Delta wing configuration has been investigated through wing-surface pressure measurements, the off-surface flow visualization, and 5-hole probe measurements of the wing wake section. The description focused on analyzing the interaction and the breakdown of vortices depending on the angle of attack and the sideslip angle. The Effect of angle of attack and sideslip angle on the aerodynamic load characteristics of the model is also presented. The sideslip angle was found to be a very influential parameter of the vortex flow over the LEX-delta wing configuration. The introduction of LEX vortex stabilized the vortex flow, and delayed the vortex breakdown up to a higher angle of attack. The vortex interaction and breakdown was promoted on the windward side, whereas it was suppressed on the leeward side.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.388-393
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• 2001

An experimental study is conducted to investigate the interaction of vortices over a delta wing with leading edge extension(LEX) through the off-surface flow visualization and the 5-hole probe measurements of the wing wake region. Especially, the application of a new visualization technique is employed by ultrasonic humidifier water droplet and laser beam sheet. The results, both the off-surface visualization and the 5-hole probe, show that LEX tends to stabilize the vortices of the delta wing up to the high angle of attack even though the model is yawed. With increasing yaw, the windward leading edge vortex moves inward, and closer to the wing surface, while the leeward vortex moves outwards and away from the wing surface. The vortex interaction is promoted in the windward side, and is delayed in the leeward side.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.9
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• pp.761-770
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• 2007

In this study, a swirl generator using delta wing was developed in order to simulate total pressure distortion and flow angle distortion. The delta wing was used for $65^{\circ}$-degree sweep back angle to satisfy the design performance for vortex core position, total pressure distortion(DC90) and swirl angle. To extend the swirling flow area, a $45^{\circ}$-degree vortex flap have applied to the delta wing. The swirl generator satisfied the design requirement of distortion coefficient in the flow distortion test to be applied to the simulation duct, and the performances of distortion for vortex core position and swirl angle using CFD(computational fluid dynamics) analysis results that was verified by flow distortion test results.