수직이착륙 무인기용 Ducted Fan 및 로터의 공력성능 비교

박영민,방현석,정진덕,이해창 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.11

Ducted Fan 추진 장치는 저소음 특성과 정지비행 시 덕트의 추가 추력으로 인한 높은 효율로 인해 무인기 등의 추진 장치에 자주 거론된다. 이에 본 논문에서는 Ducted Fan의 수직이착륙 무인기로의 적용 가능성을 확인하기 위하여 정지비행 및 축방향 전진비행 조건에서 Ducted Fan과 로터의 성능을 전산유체역학을 통해 해석하고 성능을 비교하였다. 해석결과 Ducted Fan은 정지비행 시 동일한 동력 조건에서 로터보다 높은 추력을 보인 반면, 전진비행 조건의 경우 Duct로 인한 항력 때문에 매우 제한된 조건에서만 우수한 성능을 보였다. 결국 Ducted Fan은 정지비행이나 저속 무인기에 적합하며 고속 무인기의 추진시스템으로는 적합하지 않음을 확인할 수 있었다. Due to the high hovering efficiency and low noise characteristics, the ducted fan is frequently mentioned for VTOL aircraft propulsion system. In the present paper, to verify the application of ducted fan to VTOL UAV propulsion system, aerodynamic performances of the ducted fan and open rotor are investigated using computational fluid dynamics approaches. The results showed that the ducted fan showed outstandingly higher hovering efficiency compared to the open rotor. In axial forward flight condition, however, the ducted fan showed lower efficiency except low speed and hovering region due to the drag increase of the duct. Finally, it was shown that the ducted fan propulsion system is suitable for hovering or low speed UAV and not for high speed UAV.

다중 덕트 팬 전진 비행 특성에 대한 수치적 연구

노나현(Nahyeon Roh),오세종(Sejong Oh),박동훈(Donghun Park) 한국항공우주학회 2018 韓國航空宇宙學會誌 Vol.46 No.2

차세대 회전익기 개발에서 고속화는 중요한 과제이며, 선행 연구들을 통해 덕트 팬을 가지는 비행체는 고속화 실현 가능성이 높은 형상으로 평가된다. 본 연구에서는 다중 덕트팬 비행체의 전진 비행시의 유동 특성 및 공력 성능 분석을 위한 전산해석을 수행하였다. 전방 팬의 공력 성능은 자유류 유동과 팬 유입류에 의해 결정되는 반면, 후방 팬의 성능은 전방 팬에서 발생한 유동에 지배적인 영향을 받음을 확인하였다. 전진 속도가 증가하며 전방 팬 입구에서의 유동 박리는 후방 팬보다 먼저 발생하며, 덕트 입구 박리는 팬 추력의 증가를 유도한다. 두 덕트 팬 간의 상호 작용으로 인해 후방 팬에는 상대적으로 정렬된 유동이 유입되므로 박리 이전까지 추력이 꾸준히 감소하고, 전/후방 팬의 추력의 급격한 변화는 동시에 발생한다. 전진 속도에 따라 전체 비행체의 수직력은 감소하였다. 이는 팬 후류에 의한 동체 아랫면 압력 저하가 주요 원인으로 분석되었다. Increasing cruise speed is an important issue for the development of the next generation rotorcraft. Among several concepts proposed by previous research, the rotorcraft with ducted fan demonstrates its possibility of high-speed flight. In this study, numerical simulations are conducted to investigate the aerodynamic and flow characteristics of multi-ducted fan in forward flight. The aerodynamic efficiency around front ducted fan is determined by interaction between free-stream velocity and the induced velocity. While flow characteristics of rear ducted fan are dominantly influenced by the front ducted fan. Separation in the front ducted fan occurs faster than that of rear ducted fan, and the separation at duct inlet induces an increase of fan thrust. As a result of interaction effect between each ducted fan, relatively aligned inflow enters to the rear ducted fan. Therefore, thrust of the rear fan is decreased steadily before separation, and sudden changes of thrust in fans occur simultaneously. Due to the pressure decrease on lower surface, the normal force of rotorcraft is reduced with forward speed.

Effect of Vortex Design on a Half-Ducted Axial Flow Fan (In the case of forced vortex design)

Kaji, Atsushi,Kinoue, Yoichi,Shiomi, Norimasa,Setoguchi, Toshiaki Korean Society for Fluid machinery 2018 International journal of fluid machinery and syste Vol.11 No.1

An improvement of the half-ducted axial flow fan design by applying the forced vortex design to the rotor blade was conducted by CFD. The quasi three-dimensional flow theory was applied for the half-ducted fan design, and the meridional flow was calculated by the method of streamline curvature. When the radial balance equations from hub to tip was solved, the vortex design was changed from the constant-whirl-velocity design to the forced vortex design in reference to our previous experimental results of the half-ducted fan's internal flow. The analysis of the three-dimensional internal flow fields of the half-ducted fan designed by adopting the forced vortex design was conducted. As a result of CFD, the efficiency ${\eta}$ of the fan was about 1-3 % larger at the flow rate coefficient ${\phi}$ of 0.158-0.343 than the constant-whirl-velocity design.

A Study on the Optimal Installation of Ducted Fan Ventilation System in Long Mine Airways

Chang Woo Lee(이창우),Van Duc Nguyen(응우엔반득) 한국암반공학회 2017 터널과지하공간 Vol.27 No.1

국내 석회석광산은 주로 자연통기에 의존하고 있으나 자본 및 운전비용이 과다하게 소요되는 광산 전체통기방법보다 풍관과 선풍기를 이용한 국부통기방법이 바람직한 방법으로 평가된다. 국내 대단면 장대 광산갱도에 풍관이 접속된 국부선풍기를 직렬로 연결 설치하는 경우에 통기시스템의 경제성과 효율의 최적화가 반드시 요구된다. 최적화를 위한 가장 중요한 두가지의 설계변수는 벽면 이격거리와 풍관 간의 이격거리이다. 본 연구에서는 경제적 및 환경적으로 최적화된, 즉 풍관간의 이격 공간을 통한 압력손실, 누기 그리고 오염된 공기의 재유입을 최소화할 수 있는 두 설계변수 값을 도출하기 위하여 광범위한 CFD분석을 시행하였다. 기존 연구결과와 권고기준들을 고려하여 이들 변수의 연구대상 범위를 선정하였다. 본 연구의 궁극적 목표는 국내 장대 광산갱도내 설치되는 풍관 접속 선풍기의 직렬연결 국부통기시스템의 최적화를 통하여 깨끗하고 안전한 작업장 환경을 제공하기 위함이다. In local underground mines heavily depending on the natural ventilation, ducted fan auxiliary ventilation system is strongly recommended instead of the total mine ventilation system requiring large capital and operating costs. Optimizing the installation of ducted fans in series in long large-opening mines is required to assure the economy and efficiency of the ventilation system. The two most critical design parameters for optimization are the wall separation distance and gap length between adjoining ducts. This study aims at deriving the optimal values for those two parameters concerning the economic and environmental aspects through the extensive CFD analysis, which minimizes pressure loss, leakage and entrainment of the contaminated air in the gap space. The ranges of the wall separation distance and gap length for study are selected by taking into consideration the existing recommendations and guidelines. The ultimate goal is to optimize the auxiliary ventilation system using ducted fans in series to provide a reliable and efficient solution to maintain clean and safe workplace environment in local long underground mines.

덕트 내부 형상이 무인기용 덕티드 팬의 성능에 미치는 영향

이광민(K.M. Lee),김철완(C.W. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.11

Ducted fans that are popular choices in Vertical take-off and landing (VTOL) unmanned aerial vehicles (UAV) offer a higher static thrust/power ratio for a given diameter than open propellers. Although ducted fans provide high performance in many UAV applications, there havent been well-studied on the internal shape of ducts. In the present study, the aerodynamic characteristics of the ducted fan composed a 34cm diameter duct and 5 blades investigated based on Reynolds-Averaged Navier-Stokes (RANS) and SST model. RANS prediction of thrust performance was compared to the wind tunnel test data. Comparison of internal duct shapes shows results affecting the overall performance of the ducted fan. As the depth of furrow on the duct and tip clearance change, the thrust performance also changes.

Experimental Study on Tip Clearance Effects for Performance Characteristics of Ducted Fan

Iliyas Raza,Hyunmin Choi,Jinsoo Cho 한국추진공학회 2009 한국추진공학회 학술대회논문집 Vol.2009 No.11

Currently, a new generation of ducted fan UAVs (Unmanned Aerial Vehicles) is under development for a wide range of inspection, investigation and combat missions as well as for a variety of civil roles like traffic monitoring, meteorological studies, hazard mitigation etc. The current study presents extensive results obtained experimentally in order to investigate the tip clearance effects on performance characteristics of a ducted fan for small UAV systems. Three ducted fans having different tip clearance gap and with same rotor size were examined under three different yawed conditions of calibrated slanted hot-wire probe. Three dimensional velocity flow fields were measured from hub to tip at outlet of the ducted fan. The analysis of data were done by PLEAT (Phase locked Ensemble Averaging Technique) and three non-linear differential equations were solved simultaneously by using Newton ?Rhapson numerical method. Flow field characteristics such as tip vortex and secondary flow were confirmed through axial, radial and tangential velocity contour plots. At the same time, the effects of tip clearance on axial thrust and input power were also investigated by using wind tunnel measurement system. For enhancing the performance of ducted fan, tip clearance level should be as small as possible.

팁 간격이 덕티드 팬의 공력 및 소음 성능에 미치는 영향에 관한 전산해석

황유현,김시진,조규철,명노신,이학진 한국전산유체공학회 2023 한국전산유체공학회지 Vol.28 No.4

A ducted fan offers improved safety by preventing object collisions and shielding the rotating blades. The tip clearance is an important parameter that can control the strong vortex generated at the rotating blade tips and impacts the performance. This study conducted computational analysis to investigate the effect of tip clearance on the aerodynamic performance and noise level of a ducted fan in hover condition using lattice-Boltzmann method (LBM) simulations. The tip clearance was defined as s/R = 1%, 2%, 4% using propeller radius(R), and computational analysis was conducted, including an propeller without duct. The thrust contribution of duct system was confirmed through the axial velocity field and surface pressure contour on ducted fan. Duct Shielding effect and aerodynamic noise level were investigated by comparing the overall sound pressure level (OASPL). Moreover, the directionality of noise propagation was observed using the instantaneous sound pressure field with various tip clearances. As a result, the strength of blade tip vortex increased as the tip clearance increased, thus leading to increase in tonal and broadband noise. It was concluded that a reduced tip clearance demonstrated enhanced noise reduction performance for the ducted fan.

Study on Influence of Blade Number on Aerodynamic Noise of Half-ducted Propeller Fans for Packaged Air-conditioners

Taku Iwase,Tetsushi Kishitani,Masato Furukawa 한국유체기계학회 2017 International journal of fluid machinery and syste Vol.10 No.4

Flow fields in 2-blade and 4-blade half-ducted propeller fans for the outdoor units of air-conditioners were calculated with large eddy simulation based on finite element method with the aim of investigating the influence of blade number on aerodynamic noise. We confirmed that the tip vortex had a great influence on aerodynamic noise in half-ducted propeller fans. The length of the tip vortex trajectory and the blade pitch for the 2-blade propeller fan were longer than those for the 4-blade propeller fan. These were suppressed the interaction between the tip vortex and the adjacent blade in the 2-blade propeller fan. The 2-blade propeller fan was therefore more silent than the 4-blade propeller fan.

Effect of Vortex Design on a Half-Ducted Axial Flow Fan

Atsushi Kaji,Yoichi Kinoue,Norimasa Shiomi,Toshiaki Setoguchi 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.1

An improvement of the half-ducted axial flow fan design by applying the forced vortex design to the rotor blade was conducted by CFD. The quasi three-dimensional flow theory was applied for the half-ducted fan design, and the meridional flow was calculated by the method of streamline curvature. When the radial balance equations from hub to tip was solved, the vortex design was changed from the constant-whirl-velocity design to the forced vortex design in reference to our previous experimental results of the half-ducted fan’s internal flow. The analysis of the three-dimensional internal flow fields of the half-ducted fan designed by adopting the forced vortex design was conducted. As a result of CFD, the efficiency η of the fan was about 1-3 % larger at the flow rate coefficient ø of 0.158-0.343 than the constant-whirl-velocity design.

삼중 덕티드 팬 비행체 운동모델링 및 리아푸노프 제어를 이용한 안정화

나경석(Kyung Seok Na),원대희(Dae Hee Won),윤석환(Seok Hwan Yoon),성상경(Sang Kyung Sung),류민형(Min Hyoung Ryu),조진수(Jin Soo Cho),이영재(Young Jae Lee) 한국항공우주학회 2012 韓國航空宇宙學會誌 Vol.40 No.7

로터를 이용한 무인비행체는 노출된 블레이드로 운용 시 위험이 따른다. 반면 덕티드팬은 블레이드 주위를 덕트로 감싸 위험요소를 줄여주고, 동일 동력 하중을 사용한 로터보다 향상된 추력성능을 보인다. 본 논문에서는 덕티드 팬의 장점을 적용하고자 세 개의 덕티드 팬으로 구성된 삼중 덕티드 팬 비행체 형상을 제안한다. 크기가 동일한 두 개의 덕티드 팬과, 크기가 다른 한 개의 덕티드 팬으로 구성되며 3개의 덕티드 팬 중 하나는 추력 방향 조절을 통해 신속한 자세 제어가 가능하다. 삼중 덕티드 팬 비행체의 운동방정식을 유도 하였고, 리아푸노프 함수를 적용하여 시스템을 안정하게 하는 제어 입력을 도출하였다. 그리고 비행체 초기모델의 파라미터를 적용하여 비선형 모델 시뮬레이션을 통해 안정한 자세각이 출력됨을 확인하고 결과를 분석하였다. Because of the exposed blade, the UAV using the rotors entail the risks during operation. While a wrapped duct around the fan blades reduces risks, it is a higher thrust performance than the same power load rotor. In this paper, for applying advantages of a ducted fan, the tri-ducted fan air vehicle configuration is proposed. The vehicle has three ducted fans. Two of them are the same shape and size and the third one is the smaller. It is possible to control a rapid attitude stability using thrust vector control. The equations of motion of the tri-ducted fan were derived. Lyapunov control input was applied to the system and stable inputs were derived. A nonlinear simulation was fulfilled by using parameters of a prototype vehicle. It verified a stable attitude and analyzed results.