• Title/Summary/Keyword: 프로펠러 형상

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Computational Simulation of Coaxial eVTOL Aircraft in Ground Effect (동축 반전 전기동력 수직이착륙기의 지면 효과에 대한 전산해석)

  • Yang, Jin-Yong;Lee, Hyeok-Jin;Myong, Rho-Shin;Lee, Hakjin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.9
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    • pp.599-608
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    • 2022
  • Urban air mobility (UAM) equipped with rotor system is subject to ground effect at vertiport during takeoff and landing. The aerodynamic performance of the aircraft in ground effect should be analyzed for the safe operation. In this study, The ground effects on the aerodynamic performance and wake structure of the quadcopter electric vertical takeoff and landing (eVTOL) configuration equipped with coaxial counter-rotating propellers were investigated by using the lattice Boltzmann method (LBM). The influence of the ground effect was observed differently in the upper and lower propellers of the coaxial counter-rotating propeller system. There was no significant change in the aerodynamic performance of the upper propeller even if the propeller height above the ground was changed, whereas the averaged thrust and torque of the lower propeller increased significantly as propeller height decreased. In addition, the amplitude of the thrust fluctuation tended to increase as the propeller height decreased. The propeller wake was not sufficiently propagated downstream and was diffused along the ground due to the outwash flow developed by the ground effect. The impingement of the rotor wakes on the ground and a fountain vortex structure were observed.

Airframe Weight Estimation Method for Initial Sizing of Multicopter (멀티콥터 초기 사이징을 위한 기체 구조 중량 예측 기법)

  • Jang, Byeong-Wook;Hwang, In-Seong;Kim, Minwoo;Lee, Bosung;Jung, Yongwun;Kang, Wanggu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.9
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    • pp.723-734
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    • 2018
  • A structural weight estimation methodology for the multicopter design process is presented. In general, a multicopter is composed of an airframe, motors, propellers, battery and so on. Among these, the weight of motors, propellers and battery can be obtained from the weight trends with respect to design parameters. However, the structural weight is hard to be estimated due to the various configurations and design concepts of multicopters. Moreover, the airframe weights of most commercial multicopter products are not provided. Thus, an accurate airframe weight model is required for the reliable mutlcopter design process. Firstly, the standard configuration of multicopters is defined. Then, we proposed the structural weight estimation method using the number and diameter of propellers determined from the initial step of sizing process. Finally, we validated our suggested method using the commerical products.

Prediction of Rolling Moment for a Hand-Launched UAV Considering the Interference Effect of Propeller Wake (프로펠러 후류 간섭 효과를 고려한 투척식 무인기 롤 모멘트 예측)

  • Sang-Mann, Woo;Dong-Hyun, Kim;Ji-Min, Park
    • Journal of Aerospace System Engineering
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    • v.16 no.6
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    • pp.114-122
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    • 2022
  • This paper explores three-dimensional unsteady computational fluid dynamic (CFD) analyses with an overset grid technique to analyse the wake effect created by a rotating propeller on a hand-launched unmanned aerial vehicle (UAV). Additionally, the influence of actual aileron deflection on the equilibrium condition of the rolling moment is examined in various hand-launched take-off conditions. The results of this study demonstrate the importance of initial aileron deflection in increasing the initial rolling stability during the hand-launched take-off process. Furthermore, an aerodynamic database is constructed to rapidly predict the aileron set values required for different take-off speeds and angle-of-attacks.

A Study of a Correlation between Experiments and Calculations of Pressure Fluctuation on Hull Surface (선체 변동 압력에 관한 실험과 이론의 비교 연구)

  • Moon-Chan Kim;Ki-Sup Kim;In-Haeng Song
    • Journal of the Society of Naval Architects of Korea
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    • v.33 no.1
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    • pp.19-26
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    • 1996
  • An experimental and computational study of the pressure fluctuation induced by a propeller on a hull surface was carried out with three ship models and seven model propellers. The fluctuation of pressure on a flat plate was measured at KRISO cavitation tunnel and calculated by a panel and lifting surface method(XForShip code). To extend the measurement data on the flat plate into that on complex hull forms, the correction factor was determined as a ratio of the solid boundary factor(SBF). The computation of pressure fluctuation around complex hull forms was also performed to make the full scale prediction and compared with the corrected experimental data. The calculated values agreed well with the compensated experimental data and it was found that the correction factor was about 0.65-0.7.

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Gouging-free Tool-path Generation for Manufacturing Model Propellers (모형 프로펠러 제작을 위한 과절삭이 없는 공구 경로 생성)

  • Kim, Yoo-Chul;Kim, Tae-Wan;Suh, Jung-Chun
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.2 s.152
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    • pp.198-209
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    • 2007
  • In this paper, we present the gouging and collision-free tool-path generation for manufacturing model propellers using the 5-axis NC machine. Because it takes much time to generate tool-paths when we use general purpose CAD/CAM systems, a specific system would be necessary for marine propellers. Overall manufacturing process is composed of two steps: roughcut and finishcut steps. The roughcut is conducted using only 3-axis for efficient machining and the finishcut is done using 5-axis for avoiding collision. The tool-path that might happen to gouging is searched and the tool position is also decided for avoiding interference between the tool and the propeller blades. The present algorithm is applied extensively to the surface piercing propellers. Some results are demonstrated for its validation.

A Study on the Development for the Coastal Fishing Boat attached Protected-Tunnel for Propeller (세미워터제트형 연안어선 개발에 관한 연구)

  • 고재용;심상목;박충환;서성부;배동균
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2003.05a
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    • pp.16-20
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    • 2003
  • Recently, The fast change of fishing boat fishery surrounding environment is connected by request of fan shape development that meet in restructuring of existing fishing boat fishery and new community, economical surrounding. In southern sea district along the coast work and district along the coast fishing bats that sail to exposed propeller fishing net, rope etc.. cold real condition that accident is increasing every year. This study is thing which analyze main performance of minuteness water jet type district along the coast fishing boat through model examination to propeller protection tunnel sticking district along the coast fishing boat that correct existing stem shape for marine accident prevention of district along the coast fishing boat in viewpoint such as ideal and examines.

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Numerical Technique to Analyze the Flow Characteristics of a Propeller Using Immersed Boundary Lattice Boltzmann Method (가상경계 격자볼쯔만법을 이용한 프로펠러의 유동특성해석 방법에 관한 연구)

  • Kim, Hyung Min
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.7
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    • pp.441-448
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    • 2016
  • The thrust force created by a propeller depends on the incoming flow velocity and the rotational velocity of the propeller. The performance of the propeller can be described by dimensionless variables, advanced ratio, thrust coefficient, and power coefficient. This study included the application of the immersed boundary lattice Boltzmann method (IBLBM) with the stereo lithography (STL) file of the rotating object for performance analysis. The immersed boundary method included the addition of the external force term to the LB equation defined by the velocity difference between the lattice points of the propeller and the grid points in the domain. The flow by rotating a 4-blade propeller was simulated with various Reynolds numbers (Re) (including 100, 500 and 1000), with advanced ratios in the range of 0.2~1.4 to verify the suggested method. The typical tendency of the thrust efficiency of the propeller was obtained from the simulation results of different advanced ratios. It was also necessary to keep the maximum mesh size ratio of the propeller surface to a grid size below 3. Additionally, a sufficient length of the downstream region in the domain was maintained to ensure the numerical stability of the higher Re and advanced ratio flow.

멤브레인형 LNG선의 진동에 관한 고찰

  • Choe, Jong-Pil;Kim, Mun-Su;Lee, Gi-Mun;Gwon, Jong-Hyeon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.868-875
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    • 2000
  • 이 연구의 목적은 당사에서 제작한 멤브레인형 $130,000M^3$$135,000M^3$ LNG 운반선의 진동특성을 파악하고, 거주구역의 진동수준을 예측하기 위함이다. 우선 공진 회피의 관점에서 최적의 프로펠러를 선택하기 위해 간단한 계산을 수행한 후, 주변 해수를 고려한 선박 전체를 모델링하여 3차원 유한요소해석을 수행한다. 이 계산은 보다 정확한 고유진동수를 결정하고, 프로펠러 기진의 주파수 범위에서 관련된 모드 형상을 결정하며, 선박 거주구에서 기대되는 진동수준은 잘 예측할 수 있다. 다음으로 선박이 진수되고 전체구조가 조립된 후 안벽에서 불평형 가진기를 이용해 가진기테스트를 실시하고, 해상시운전 중에도 동일한 방법으로 테스트를 실시한다. 시험은 고유진동수의 항으로 선박의 실제진동응답과 계산결과와의 좋은 비교를 가능하게 한다. 추가적으로 실제 엔진을 구동해 RPM을 최저에서 최고까지 천천히 변경하면서 실제 운항 중 진동응답을 계측함으로서 고유진동수를 예측하여 해석결과 및 가진기 시험결과와 비교한다.

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Development of aerodynamic noise prediction technique for high efficiency and low noise design of unmanned aerial vehicle propeller (멀티로터형 무인항공기 프로펠러의 고효율 및 저소음 설계를 위한 공력 소음 예측 기법 개발)

  • Gwak, Doo Young;Lee, Soogab
    • The Journal of the Acoustical Society of Korea
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    • v.36 no.2
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    • pp.89-99
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    • 2017
  • Multi-rotor type UAV (Unmanned Aerial Vehicle)s are expanding their applications not only for military purposes but also for private industries such as aerial photography and unmanned delivery vehicles. For wider use of unmanned aerial vehicles, studies should be carried out to improve aerodynamic efficiency and reduce noise of propellers, which can be achieved based on techniques of predicting aerodynamic performance and noise in a given environment. In this study, aerodynamic and noise prediction techniques were developed for a small unmanned aerial vehicle propeller, and it was verified by comparing it with actual measurement results. Thrust and torque due to the change of r/min and the frequency spectral prediction at a given position secured the reliability of the prediction method, which provides a basis for the shape design of the propeller.

Design and Performance Analysis of Propeller for Solar-powered HALE UAV EAV-3 (고고도 장기체공 태양광 무인기 EAV-3의 프로펠러 설계 및 성능해석)

  • Park, Donghun;Hwang, Seungjae;Kim, Sanggon;Kim, Cheolwan;Lee, Yunggyo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.9
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    • pp.759-768
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    • 2016
  • Design and performance analysis of propeller for solar-powered HALE UAV, EAV-3 are conducted. Experiment points of design variables are obtained by using Design of Experiment(DOE) and Kriging meta-model is generated for objective and constraints function. The geometry of propeller is designed by evaluating the response surface with requirement and restrictions. The validity of the design is verified by meta-model based optimization. Computational analyses are carried out by using commercial CFD code and the results are compared with those from a design code and wind tunnel test. The results showed good agreement with predictions of the design code at the design altitude. Also, it is confirmed that the blockage effect due to the measurement device and support strut is included in the test data and the results including this effect compare well with the test data.