• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 춘계 학술대회논문집
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• pp.196-201
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• 2004

Aerodynamic characteristics of three-dimensional wings in ground effect for Aero-levitation Electric Vehicle(AEV) are numerically investigated for various ground clearances and wing spans at the Reynolds number of $2\times10^6$. Numerical results show that a sizeable three-dimensional flow separation occurs with formation of an arch vortex at the junction of main and vertical wings, and that this is conjectured a primary cause for the high lift-to-drag(L/D) reduction rate of the main wing, when the wing span is decreased. Improvements on L/D ratios of the wings with small spans are pursued by breaking the coherence of superimposed adverse pressure gradients at the wing junction.

• 한국해양공학회지
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• 제12권2호통권28호
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• pp.87-96
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• 1998

A numerical simulation was done to investigate the performance of thin wings in close vicinity to ground. The simulation is based on Vortex Lattice Method(VLM) and freely deforming wake elements are taken into account for a sudden acceleration case. The parameters covered in the simulation are angle of attack, aspect ratio, ground clearance, sweep angle and taper ratio. In addition, the effect of the wing endplate on the ground effect is included. The wing sections used for present computations are uncambered, cambered and S-types. The present computational results are compared with other published computational results and experimental data.

• 한국항공우주학회지
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• 제35권5호
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• pp.369-374
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• 2007

비평면 지면 위를 비행하는 플래퍼론이 있는 날개의 비정상 공력특성을 경계요소법을 사용하여 연구하였다. 시간 전진법을 사용하여 채널과 지면 위를 비행하는 날개 및 플래퍼론의 움직임에 따른 후류의 형상을 모사하였다. 지면 위 또는 채널 내를 비행하는 날개의 공력계수는 플래퍼론의 주기운동에 따라 일정한 루프로 나타난다. 플래퍼론 변화에 따른 롤링모멘트는 지면 위를 비행하는 날개와 채널 내를 비행하는 날개가 동일한 결과를 나타내었다. 피칭모멘트는 지면에서 보다 채널 내를 비행할 때 플래퍼론의 움직임에 따라 더 큰 변화폭을 나타내었다. 본 연구를 통해 비평면 지면 위를 비행하는 운송체의 안정성 해석에 필요한 다양한 공력계수 확보가 가능하다.

• Journal of Mechanical Science and Technology
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• 제20권7호
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• pp.1043-1050
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• 2006

The aerodynamic interaction between a wing and a rail is investigated using a boundary-element method. The source and doublet singularities are distributed on the wing and its guide-way rail surface. The unknown strengths of the singularities are determined by inverting the aerodynamic influence coefficient matrices. Present method is validated by comparing computed results with the other numerical data. Rail width and rail height affect the aerodynamic characteristics of the wing only if the rail is narrower than the wing span. Although the present results are limited to the inviscid, irrotational flows, it is believed that the present method can be applied to the conceptual design of the high speed ground transporters moving over the rail.

• International Journal of Aeronautical and Space Sciences
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• 제3권2호
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• pp.82-87
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• 2002

Aerodynamic analysis of NACA wings moving with a constant speed over guideways are performed using an indirect boundary element method (potential-based panel method). An integral equation is obtained by applying Green's theorem on all surfaces of the fluid domain. The surfaces over the wing and the guideways are discretized as rectangular panel elements. Constant strength singularities are distributed over the panel elements. The viscous shear layer behind the wing is represented by constant strength dipoles. The unknown strengths of potentials are determined by inverting the aerodynamic influence coefficient matrices constructed by using the no penetration conditions on the surfaces and the Kutta condition at the trailing edge of the wing. The aerodynamic characteristics for the wings flying over nonplanar ground surfaces are investigated for several ground heights.

• 해양환경안전학회지
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• 제19권5호
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• pp.491-496
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• 2013

수면비행선박의 지위가 국제해사기구(IMO)에서 선박으로 분류하는 것으로 결론지은 이후, 국내외적으로는 몇몇 규칙과 권고 사항들이 개정 및 승인되었다. 하지만 정작 수면비행선박의 종류 및 운항특성을 고려한 항법에 관해서는 규정이 미비하고, 수면비행선박간 항법에 관련해서는 규정이 되어 있지 않다. 이러한 상황에서, 현행 법령상에 다른 선박들과 수면비행선박간의 책임 관계를 명확히 하기 위하여 서로 시계에 항법상의 수면비행선박 관련 규정을 모든 시계로의 항법상으로 이동할 것과 수면비행선박간 안전통항을 확보하기 위하여 타입 'B'와 'C'의 수면비행선박이 타입 'A'의 수면비행선박을 피항해야 한다는 규정이 신설되어야 한다고 판단된다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.103-108
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• 2003

In the construction of mountain tunnels, reaction forces of the legs of steel arch supports against the ground are often expected to support the ground being excavated. In these cases, a stress concentration occurs in the ground directly under the support legs. If the bearing capacity of the ground is insufficient or displacement is not effectively constrained, the local failure of the ground under the support legs or settlement of the tunnel supports due to large deformation could result. It is therefore necessary to reinforce the support legs to reduce settlement. As a means of reducing settlement, wing-ribbed steel arch supports are well used. In this study, with the aim of finding a way to quickly reduce the settlement of steel arch support legs, effectiveness of a new type of wing ribs to reinforce steel arch supports was investigated through laboratory testing.

• 대한조선학회논문집
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• 제48권5호
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• pp.381-389
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• 2011

In this study, we are focusing our attention on lift characteristics of the low aspect wings for Wing-In Ground effect crafts (WIG). Experimental measurements at an open-type wind tunnel are carried out and results are comparatively presented. In order to simulate the realistic ground condition in where the WIG craft is flying, moving ground is implemented by a conveyor belt rotating with the same velocity of the inflow. We consider two different wings (NACA0012 and DHMTU section) which have four different aspect ratios (0.5, 1.0, 1.5 and 2.0). Forces acting on the wings are measured and lift characteristics are elaborately investigated for various different conditions. In addition, end-plate effects are estimated. Results are validated by comparing with theoretic solutions of the symmetric airfoil. Present results show that ground effects are differently generated in moving or fixed ground conditions, and hence left characteristics are affected by the ground condition. Consequently, accurate aerodynamic forces acting on the WIG craft are guaranteed in a realistic moving ground condition.

• Advanced Composite Materials
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• 제17권4호
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• pp.343-358
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• 2008

This present study provides the structural design and analysis of main wing, horizontal tail and control surface of a small scale WIG (Wing-in-Ground Effect) craft which has been developed as a future high speed maritime transportation system of Korea. Weight saving as well as structural stability could be achieved by using the skin.spar.foam sandwich and carbon/epoxy composite material. Through sequential design modifications and numerical structural analysis using commercial FEM code PATRAN/NASTRAN, the final design structural features to meet the final design goal such as the system target weight, structural safety and stability were obtained. In addition, joint structures such as insert bolts for joining the wing with the fuselage and lugs for joining the control surface to the wing were designed by considering easy assembling as well as more than 20 years service life.

• 한국항공우주학회지
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• 제35권6호
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• pp.483-488
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• 2007

경계요소법을 이용하여 동체에 탠덤 날개를 결합한 FAST가 비평면 지면을 비행할 때의 공력 특성을 파악하였다. 본 수치해석 기법을 이용하여 계산한 결과를 실험 및 타 전산해석 결과와 비교하여 검증을 수행하였다. 날개-동체를 결합한 운송체의 공력 특성을 분석하여 안정성 확보 및 충분한 공기부상력을 가지도록 운송체 상부의 탠덤 날개를 배치하는 공력설계를 수행하였다. FAST에서 탠덤 날개가 동체의 전두부와 후두부에 위치하고, 하단 익단판을 설치하였을 때 최대 양력 성능을 얻을 수 있었다. FAST의 안정성은 탠덤날개의 플래퍼론을 이용하여 확보 가능하다.