• 한국항공운항학회지
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• 제26권3호
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• pp.48-54
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• 2018

This paper deals with a development of a quad-rotor for a hovering attitude control. First, a rotational dynamics are derived to design an attitude controller. The attitude controller is based on PI (Proportional-Integral) controller. For a stable attitude control, an anti-windup method applies to the PI attitude controller. Additionally, a complementary filter is used to obtain more reliable attitude. Gain values of the attitude controllers based on the anti-windup method are obtained through tests. Finally, the quad-rotor with the anti-windup based PI attitude controller is developed and a hovering attitude control flight tests are performed. As a result, the developed quad-rotor is capable of stable hovering.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.151-154
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• 2006

In the present paper, hovering performance analyses of proprotor and helicopter rotor blades were performed by using FLUENT software. As a proprotor, TRAM(Tilt Rotor Aeroacoustic Model) was selected and performance analysis was carried out with mesh adaptation for more elaborate solution. As a helicopter rotor blades, two bladed Caradonna and Tung's rotor and four-bladed BO-105 helicopter rotor blades were selected. In case of Caradonna and Tung's rotor, vortex trajectory was compared with experimental data to inspect the vortex convection capability of the present flow solver. For the final case, performance of BO-105 helicopter rotor blades was investigated and compared with experimental data. After performance analyses of proprotor and helicopter rotors, it was shown that the present solver showed reasonable vortex strength, wake geometry and thurst coefficient distributions. But power coefficient was somewhat overestimated about $10%{\sim}15%$ regard less of mesh adaptation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.996-1000
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• 2003

In this paper, Fly robot with electric power, a kind of Unmanned aerial vehicle (UAV), is considered as an autonomous hovering platform, capable of vertical lift-off, landing and stationary hovering. This aircraft has four rotor and DC motors of electrical Power, which is capable of omni-direction for indoor application. In the earlier days of vertical flight experimentation developers looked at the intuitively easy control functionality of 4 rotor designs. But we need to obtain design method of suitable structures and adequate components because the existing prototypes of 4 rotor-craft don't analyze the propeller, motor characteristic and propose a methodology to optimize this system. In this paper, we will show the new 4 rotor craft with blimp, analyze design and manufacturing method of 4 rotor craft system. Also we prove propriety of our design and manufacturing method by being based on thrust and motor experiment.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.427-430
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• 2006

The ground effect on tilt-rotor UAV is analyzed by simulating the hovering UAV for various altitudes. Ground effect increases pressure beneath the UAV body and generates additional lifting force. The ground effect diminishes at altitude 3m and hovering UAV generates constant lifting force above 3m.

• 한국전산유체공학회지
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• 제13권4호
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• pp.45-49
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• 2008

The present paper describes the results of performance analysis for UH-60A rotor blade in hover. For the numerical simulations, commercial CFD software, FLUENT was used with Spalart-Allmaras turbulence model. The flow solver was based on node based scheme and second order spatial accuracy options was used for simulations. For the enhancement of wake capturing capability, high resolution grid was used around tip vortex region. Granting that somewhat over-prediction of thrust was observed near blade tip region, performance was well correlated with experimental data within 3% accuracy in the operating region. Finally it was shown that the present flow solver can be used as a preliminary performance analysis tool for hovering helicopter rotor blades.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.73-76
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• 2007

The present paper describes the results of performance analysis for UH-60A rotor blade in hover. For the numerical simulations, commercial CFD software, FLUENT was used with Spalart-Allmaras turbulence model. The flow solver was based on node based scheme and second order spatial accuracy options was used for simulations. For the enhancement of wake capturing capability, high resolution grid was used around tip vortex region. Granting that somewhat over prediction of thrust was observed near blade tip region, performance was well correlated with experimental data within 3% accuracy in the operating region. Finally it was shown that the present flow solver can be used for preliminary performance analysis tool for hovering helicopter rotor blades.

• 산업기술연구
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• 제8권
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• pp.31-35
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• 1988

To predict the airloads on helicopter rotors in hover, the doublet panel method of the first order is applied. For this simulation, the rotor blade is divided into many panels both in spanwise and in chordwise direction, and Kocurek-Tangler's prescribed wake with roll-up process is taken for determing wake geometry and then represented by vortex lattice. To abtain more physically realistic calculation of induced velocity, the vortex core model is adopted and the compressibility effect is considered by Karman-Tsien rule.

• 한국기계가공학회지
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• 제21권5호
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• pp.53-60
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• 2022

In this study, the conceptual design and performance evaluation of a personal air vehicle (PAV) is presented, which is a potential futuristic individual transportation. The blade element theory (BET) is employed to compute a rotational velocity. A computational fluid dynamics (CFD) simulation is performed to investigate the difference in the thrust performance in the rotor axis distance of a quad-copter PAV in hovering. Modal analysis is performed to create a Campbell diagram to investigate critical speed. Consequently, a quad-copter PAV changes the aerodynamics thrust and critical velocity according to the rotor axis distance.

• International Journal of Aeronautical and Space Sciences
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• 제10권1호
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• pp.20-29
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• 2009

There are concerns about the influence of the gust wind caused by helicopters affecting the moving vehicles while hovering over the road during rescue activities. For the understanding of such complicated flow. numerical simulation of a rotor hovering above the ground has been carried out, changing the rotor/ground clearances. The rotor thrust is kept constant. and the rotor control is determined by trim adjustments incorporated into the CFD algorithm. Collective pitch angle and the required power decreases with the rotor/ground clearance which agrees with experience. Changes of the flowfield near the rotor with regard to the rotor height are investigated based on the calculated results.

• 한국항공우주학회지
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• 제49권8호
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• pp.699-708
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• 2021

본 논문에서는 제자리 비행하는 동축반전 로터의 설계 파라미터인 상하부 로터의 축 간격에 따른 공력 특성 및 공력소음 특성에 관해 전산유체해석을 통해 분석하였다. Reynolds Averaged Navier Stokes 방정식을 사용하여 공력 해석을 진행하였으며 공력소음 해석 시에 Ffowcs Williams ans Hawkings 방정식을 사용하여 공력 특성 및 공력소음 특성을 비교하였다. 동축반전 로터는 회전에 의해 상하부 로터가 다른 각도를 가지며, 위상이 주기적으로 변하는 비정상 특성을 가진다. 상하부 로터의 간격이 증가함에 따라 유동 상호간섭이 감소하여 추력 및 토크의 공기역학적인 효율이 증가함을 확인하였다. 공력소음 관점에서 회전 평면 방향으로 방사하는 소음 특성은 축 간격에 의한 영향이 미미하게 나타났다. 로터 수직 아래 방향으로 주파수가 증가함에 따라 음압이 감쇄하지 않고 크기가 유지되어 전체 음압 수준을 증가시킨다. 동축반전 로터의 축 간격이 증가함에 따라 유동의 비정상 특성이 감소하여 전체 음압 수준이 크게 감소함을 확인하였다.