• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.7
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• pp.565-574
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• 2007

The flow control effect of blending Gurney flap with jet flap for flow around an NACA 0012 airfoil was numerically investigated through parameter variation of each flow control mechanism on unstructured meshes. The aerodynamic force and moment variations due to flow control were examined, and the results were compared between the blending control and each individual flow control. The results showed that the blending control required less energy input to achieve the same level of lift increment than that of the jet flap, and at the same time alleviated drag increment caused by introducing the Gurney flap.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.537-540
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• 2016

유체역학적 추력 방향 제어(Fluidic Thrust Vector Control) 방법 중 하나인 동축류 제어 유동 분사를 이용한 추력 방향 제어(Co-flow Thrust Vector Control)의 작동 특성에 대해서 연구하였다. 이 제어 방법은 점성 유동이 벽면에 부착되어 흐르는 코안다 효과(Coanda Effect)를 이용하여 주 유동을 편향 시키는 방법으로서 그 편향각은 이러한 제어 유동 노즐 출구의 플랩 형상에 영향을 받는 것으로 알려져 있다. 이 연구에서는 출구 플랩 형상을 여러 가지로 바꾸어 가며 주 유동의 전압력 300kPa일 때 제어 유동의 편향각이 포화되는 제어유동의 전압력을 측정하였다. 그 결과 쐐기형 플랩의 각도가 증가할수록 포화 영역에서의 편향각은 증가하며 그 각은 플랩의 각도와 일치한다. 그러나 각도가 증가할수록 제어 유동이 플랩의 벽면을 지나면서 팽창파에 의해 가속되어 충격파을 발생시키게 되고 이 충격파는 주 유동에게까지 전파되어 주 유동 제트의 속도를 감소시킨다.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.24-30
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• 2016

An experimental study for the characteristics of the thrust-vectoring of a sonic jet utilizing the coanda flap installed at a rectangular nozzle exit is performed. Two side plates are installed at both sides of the flap to decrease the three dimensional effects of the jet on the flap surface. Schlieren flow visualizations and quantitative measurements of the deflection angle of thrusting vector show that the side plates are able to delay the separation of the jet at the downstream of the flap surface. Substantial increase in the deflection angle of the jet as high as $72^{\circ}$ and small thrust loss as low as 7% are obtained by the present thrust-vectoring technique using the side plates.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.3
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• pp.1-9
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• 2011

In this paper, a conceptual design process for Very Light Jet aircraft has been proposed incorporating aircraft safety certification. During the proposed design process, satisfaction of the airworthiness certification for an intermediate resulting aircraft configuration is evaluated and then redesigns are carried out if necessary and until the designed aircraft configuration satisfies the airworthiness requirements. Certification database has been developed using FAR 23, AC 23, KAS 23, and CS 23 as the airworthiness certification. Based on the developed certification database Design Certifcation Related Table has been produced to use the airworthiness requirements as design constraints in the propsed design process. Using Quality Function Deployment the design variables for a redesign are carefully selected and a design optimization is performed. To demonstrate the feasibility and effectiveness of rapid aircraft conceptual design using the proposed approach, a Very Light Jet design optimization including a redesign of wing flap has been performed and the design results have been presented.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.4
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• pp.21-27
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• 1999

A low order panel method based on the perturbation potential is applied for prediction of performance of blown-flap rudders. In order to improve the solution behavior at the large angle of attacks, the geometry of the trailing wake sheet is computed by aligning freely with the local flow. The effect of the wake sheet roll-up is also included with use of a high order panel method. The flow in the gap between the main component and the flap of the rudder is modeled as Couette flow. The effects of the gap and the flow jet are included in application of a kinematic and a dynamic boundary condition on the inlet and the outlet of the gap as well as on the flap and the wake. The results with the present method are compared with existing experimental data. The method is shown to be capable of determining accurately the flow characteristics even for large flap angles.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.1
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• pp.22-29
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• 1999

In the development of high speed marine vehicle, lilting devices became important in sharing the pay load or controlling the attitude. The devices are also important to meet the IMO regulation to prevent the marine pollution by keeping the high rudder force for VLCC even in low speed operation. The high lift devices such as the Coanda device have been introduced to the aircraft as a common practice for a long time among the aero-engineers. If the Coanda device can be utilized to the flapped rudder, the severe requirement of rudder force could be provided for the VLCC in low speed operation. The performance of the rudder system has been investigated at the towing tank of Seoul National University.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.11
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• pp.927-933
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• 2012

The characteristics of two-dimensional supersonic coanda flow was experimentally investigated. For various ratios of slot height to coanda wall's radius of curvature, surface roughnesses, and jet stagnation pressures, the characteristics of the supersonic coanda flow such as shock structures and hysteresis were observed by flow visualization. It was found that the characteristics of hysteresis of the coanda jet was related to the surface roughness of the coanda wall. The study was further extended for application of the tangentially injected coanda jet to control co-flowing highly compressible main jet direction. It was noticed that the stagnation pressure of the main jet as well as the ratio of the slot height to coanda wall's radius of curvature wall was an influencing factor in the performance of the fluidic thrust vectoring method.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.125-129
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• 2005

Flow control has been performed using synthetic jet on NACA23012. In order to improve aerodynamic performance, synthetic jet is located near separation paint on airfoil with leading edge droop and plain flap. The flow control using synthetic jet shows that stall characteristics and control surface performance can be improved through resizing separation vortices. Stall is delayed and stall characteristics are improved when synthetic jet is applied from separation region of leading edge droop. Control surface effectiveness is increased and lift is increased when synthetic jet applied at the flap leading edge region. The results show that aerodynamic characteristics can be improved through leading edge droop with synthetic jet at near separation and plain flap with synthetic jet at the flap leading edge. The combination of synthetic jet and simple high lift device is as good as fowler flap system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.6
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• pp.10-17
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• 2006

NACA23012익형에 대하여 synthetic jet을 이용하여 박리 제어를 수행하였다. 공력특성의 향상을 위해 앞전 droop과 plain flap의 박리 부근에 synthetic jet을 위치시켰다. 고 받음각에서 앞전 박리의 발생으로 인한 실속을 앞전 droop의 작동과 이때 발생하는 앞전 박리를 synthetic jet으로 효과적으로 지연시킬 수 있고, 또한 실속 특성을 개선 할 수 있음을 확인하였다. 양력의 향상을 위하여 plain flap을 장착하였고, 이때 발생하는 박리를 synthetic jet으로 지연시켜 제어면의 작동 효율을 증가 시킬 수 있음을 확인하였다. 앞전 droop과 plain flap으로 구성된 간단한 고양력 장치에 발생하는 박리를 synthetic jet으로 제어함으로 실속을 지연시킴과 동시에 실속 특성을 향상시키고, 최대 양력의 증가로 fowler flap에 버금가는 공력특성을 확보할 수 있음을 확인하였다.

• Journal of Navigation and Port Research
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• v.37 no.3
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• pp.257-262
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• 2013

A ship operating in rough sea may suffer from an undesirable motion which may severely degrade the performance of equipment onboard and give a person an uncomfortable feeling. Hence, roll stabilization received a considerable attention and various devices including bilge keels, stabilizing fins, gyroscopic, anti-rolling tanks, rudders and flaps have been conceived and utilized for the purpose. The Coanda effect is evident when a jet stream is applied tangential to a curved surface of a hydrofoil since then the jet increases the circulation around the foil and consequently the lift. Model tests and numerical simulation have been conducted to examine the practicality of a fixed type fin stabilizer augmented by the Coanda jet. The results show that the lift coefficient of the modified Coanda fin at the zero angle of attack identically coincides with that of the original fin at ${\alpha}=\26^{\circ}$ when Coanda jet is supplied at the rate of $C_j$ = 0.25. It is also shown that fixed type fin stabilizers for active control of the motions of ships and the other mobile units without rotation can be put to practical use if the Coanda effect is applied.