• International Journal of Aeronautical and Space Sciences
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• 제17권1호
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• pp.101-108
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• 2016

The RCS characteristics of stealth modified three-surface aircraft are analyzed in this paper. Prototype A is built with CATIA software and the three-dimensional digital models of modified stealth three-surface B and C are also designed based on carrier-based aircraft Su-33; the numerical simulation of RCS characteristics of three-surface aircraft is conducted with RCSAnsys software based on physical optics method and the method of equivalent currents; The following results are obtained by comparative analysis and mathematical statistics: (1) by the use of physical optics method and equivalent electromagnetic current method, the scattering intensity for each part of the model and RCS characteristic of the aircraft can be analyzed efficiently and accurately; (2) compared with model A, the mean RCS value of model B is reduced to 14.1% in forward direction and 48.1% in lateral direction; (3) compared with model A, the mean RCS value of model C decreases to 11.4% in forward direction and 21.6% in lateral direction. The results are expected to provide theoretical basis and technical support to the conceptual design of aircraft and stealth technology research.

• International Journal of Aeronautical and Space Sciences
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• 제15권3호
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• pp.309-319
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• 2014

This paper mainly focuses on the conceptual design and stealth performance of the three-surface military aircraft. A three-dimensional (3-D) digital mock-up of the three-surface strike fighter with stealth feature was designed and the schemes of carrying missiles were analyzed in CATIA. Based on physical optics principle and the Method of Equivalent Currents (MEC), a numerical simulation of the RCS feature of the aircraft was carried out with RCSPlus which is a software designed by Beihang University. The paper contributes to the RCS feature analysis of the whole plane and different parts on X-band, S-band and UHF-band and a comparison of RCS feature to Su-37 and T-50 military aircraft is drawn. On X-band, the pitch angle of the incident wave was $0^{\circ}$, and the result shows: (1) Compared with Su-37 aircraft, the forward scattering RCS of the three-surface strike aircraft was reduced to 14.9%, the side scattering RCS to 9.6% and the back scattering RCS to 40.2%. (2) Compared with T-50 aircraft, the forward scattering RCS was reduced to 38.61%, and the side scattering RCS to 67.26%. This paper should be useful for researchers in conceptual design and stealth technology of the military aircraft.

• International Journal of Aeronautical and Space Sciences
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• 제15권4호
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• pp.366-373
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• 2014

A conceptual design of a three-surface strike fighter was studied and stealth performance was taken into account to enhance survivability and battle effectiveness. CATIA was used to design the aircraft's three-dimensional prototype model and the weapon carriage arrangement was also studied. The aircraft's RCS characteristics and distributions under X, S, C, and L bands were simulated using the RCSPlus software, which is based on the PO method. Pressure and velocity distributions of the flow field were also simulated using CFD. A turbulence model was based on standard $k-{\varepsilon}$ function and N-S functions were used during the CFD computation. Lift coefficients, drag coefficients, and lift-to-drag ratio were obtained by aerodynamic simulation. The results showed that: (1) the average value of head-on RCS between ${\pm}30^{\circ}$ is below -3.197 dBsm, and (2) the lift coefficient is 0.34674, the drag coefficient is 0.04275, and the lift-to-drag ratio is 8.11087 when the attack angle is $2.5^{\circ}$.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1997년도 추계 학술대회논문집
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• pp.43-48
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• 1997

When computing the flow around complex three dimensional aircraft configurations, the generation of the grid is the most time consuming part. This paper presents a survey of the grid generation technique. The technique for treating problems arising in surface grid generation for complex geometries is addressed. Several example grids are shown, demonstrating the ability of the method to discretize complex geometries.

• 항공우주시스템공학회지
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• 제6권3호
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• pp.24-28
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• 2012

An actuator should be added to a existing control linkage to make manned aircraft to unmanned. But it is quiet difficult to synchronize actuator with control surface because non-linear error necessarily occurs when four-bar linkage acts in three dimensional motion. In addition, in point of controller design view, while a real-time model needs the control surface deflection as its input, controller needs the actuator command as its output. Hence, the relation between both should be investigated. In this paper, the mathematical relation between actuator and control surface deflection investigated by kinematic analysis of a plant aircraft. The performance margin of the selected actuator also was verified.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.149-156
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• 2007

A three-dimensional inviscid flow solver has been developed based on unstructured meshes for the simulation of steady and unsteady flowfields around a generic fighter aircraft and for the investigation of the aerodynamic interference between the external stores and the tail surfaces. The flow solver is based on a vertex-centered finite-volume method and an implicit point Gauss-Seidel relaxation scheme. To validate the flow solver, calculations were made for a steady flow and the computed results were compared with experimental data. An unsteady time-accurate computation of the generic fighter aircraft with external stores at transonic flight conditions showed that the external stores cause undesirable vibration on the horizontal tail surface due to the mutual interference between their wake and the horizontal tail surface. It was shown that downward deflection of the trailing edge flap significantly reduces the undesirable interference effect.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.420-427
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• 2011

In this study, numerical simulations of transonic aircraft configurations are performed with various turbulence models and the effect of turbulence models on flow separation are examined. A three-dimensional RANS code and three turbulence models are used for the study. The turbulence models incorporated to the code include Menter's ${\kappa}-{\omega}$ model, Coakley's $q-{\omega}$, and Huang and Coakley's ${\kappa}-{\omega}$, model. Using the code, numerical simulations of DLR-F6 configurations obtained from AIAA CFD Drag Prediction Workshop are conducted. Flow separations on the wing-body juncture and the wing lower surface near pylon are observed. and flow features of the regions are compared with experimental data and other numerical results.

• 한국항행학회논문지
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• 제23권1호
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• pp.1-7
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• 2019

본 연구에서는 항공기 지상 이동 fast-time 시뮬레이터를 개발하였다. 시뮬레이터는 FCFS (first-come first-served) 스케줄러로부터 생성된 스케줄을 사용하여 항공기를 지상 이동시키는데, 항공기의 움직임을 모사하기 위해 1차원 등속 이동 운동 모델을 적용하였다. 공항 내 항공기 충돌 위험이 발생하는 상황을 분석하여 총 6개의 상황으로 분류하였으며 충돌 감지 및 회피 알고리즘을 구현하여 분리 거리를 유지하고 교착 상태를 방지 하도록 하였다. 인천국제공항의 실제 운용상황을 모사한, 72대의 항공기가 포함된 시나리오에 대하여 테스트를 실시하였다. 충돌 감지 및 회피 기능을 사용하지 않은 경우, 다양한 위험 상황이 확인되었으며, 충돌감지 및 회피 알고리즘을 사용하면 위험 상황이 없어지는 대신 추가적인 지연이 발생함을 확인하였다. 또한 회피 알고리즘에서 3가지 통행 우선순위 부여 방식을 구현하여 각 방식에 따른 지연 대수와 평균 지연 시간을 비교하였다. 남은 거리 또는 남은 시간에 따라 우선 순위를 부여하는 방식이 각 상황별 최소 지연을 선택하는 방식에 비하여 전체 추가 지연이 작아짐을 확인하였다.

• Advances in aircraft and spacecraft science
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• 제10권6호
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• pp.555-572
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• 2023

Airplanes in flight collide with raindrops, and the leading edges of the airframe can be damaged when colliding with raindrops. A single waterjet testing platform was created to study rain erosion damage. Carbon fiber samples with three types of skins were studied and the mechanical properties were measured using a nanoindentation instrument. The research results show that the impact force on the sample increases with the continuous increase in the impact speed of raindrops, which leads to an increase in the damage area. Sheathing with low surface roughness is more damaged than other sheathings due to its rougher surface, and the result proves that surface roughness has a more significant effect on rain erosion damage to sheathings compared to their hardness.

• Advances in aircraft and spacecraft science
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• 제4권4호
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• pp.401-419
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• 2017

This paper presents the main outcomes of the preliminary development of the Anuloid, an innovative disk-shaped VTOL aircraft. The Anuloid has three main features: lift is provided by a ducted fan powered by a turboshaft; control capabilities and anti-torque are due to a system of fixed and movable surfaces that are placed in the circular internal duct and the bottom portion of the aircraft; the Coanda effect is exploited to enable the control capabilities of such surfaces. In this paper, results from CFD analyses and wind tunnel tests are presented. Horizontal and vertical flights were considered, including accelerated flight. Particular attention was paid to the experimental analysis of the Coanda effect via a reduced scale 3D printed model. The results suggest that the Coanda effect is continuously present at the lower surface of the Anuloid and may be exploited for the control of the aircraft. Also, very complex 3D flows may develop around the aircraft.