• Title, Summary, Keyword: aerodynamic characteristics

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Experimental and numerical studies of aerodynamic forces on vehicles and bridges

  • Han, Yan;Hu, Jiexuan;Cai, C.S.;Chen, Zhengqing;Li, Chunguang
    • Wind and Structures
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    • v.17 no.2
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    • pp.163-184
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    • 2013
  • An accurate identification of the aerodynamic characteristics of vehicles and the bridge is the premise for the coupled vibration analysis of a wind-vehicle-bridge system. At present, the interaction of aerodynamic forces between the road vehicles and bridge is ignored in most previous studies. In the present study, an experimental setup was developed to measure the aerodynamic characteristics of vehicles and the bridge for different cases in a wind tunnel considering the aerodynamic interference. The influence of the wind turbulence, the wind speed, the vehicle interference, and the vehicle position on the aerodynamic coefficients of vehicles, and the influence of vehicles on the static coefficients of the bridge were investigated, based on the experimental results. The variations in the aerodynamic characteristics of vehicles and the bridge were studied and the measured results were validated according to the results of surface pressure measurements on the vehicle and the bridge. The measured results were further validated by comparing the measured results with values derived numerically. The measured results showed that the wind turbulence, the vehicle interference, and the vehicle position significantly affected the aerodynamic coefficients of vehicles. However, the influence of the wind speed on the aerodynamic coefficients of the studied vehicle is small. The static coefficients of the bridge were also significantly influenced by the presence of vehicles.

An Investigation on Nonlinear Characteristics of Aerodynamic Torque for Variable-Speed Variable-Pitch Wind Turbine (가변속도-가변피치 풍력터빈의 공기역학적 토크의 비선형 특성에 관한 고찰)

  • Lim, Chae-Wook
    • The KSFM Journal of Fluid Machinery
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    • v.14 no.2
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    • pp.29-34
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    • 2011
  • Aerodynamic torque of wind turbine is highly nonlinear due to the nonlinear interactions between wind and blade. The aerodynamic nonlinearity is represented by nonlinear power and torque coefficients which are functions of wind speed, rotational speed of rotor, and pitch angle of blade. It is essential from the viewpoint of understanding and analysis of dynamic characteristics for wind turbine to linearize the aerodynamic torque and define aerodynamic nonlinear parameters as derivatives of aerodynamic torque with respect to the three parameters. In this paper, a linearization method of the aerodynamic torque from power coefficient is presented through differentiating it by the three parameters. And steady-state values of three aerodynamic nonlinear parameters according to wind speed are obtained and their nonlinear characteristics are investigated.

Effect of Ice accretion on the aerodynamic characteristics of wind turbine blades

  • Sundaresan, Aakhash;Arunvinthan, S.;Pasha, A.A.;Pillai, S. Nadaraja
    • Wind and Structures
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    • v.32 no.3
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    • pp.205-217
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    • 2021
  • Cold regions with high air density and wind speed attract wind energy producers across the globe exhibiting its potential for wind exploitation. However, exposure of wind turbine blades to such cold conditions bring about devastating impacts like aerodynamic degradation, production loss and blade failures etc. A series of wind tunnel tests were performed to investigate the effect of icing on the aerodynamic properties of wind turbine blades. A baseline clean wing configuration along with four different ice accretion geometries were considered in this study. Aerodynamic force coefficients were obtained from the surface pressure measurements made over the test model using MPS4264 Simultaneous pressure scanner. 3D printed Ice templates featuring different ice geometries based on Icing Research Tunnel data is utilized. Aerodynamic characteristics of both the clean wing configuration and Ice accreted geometries were analysed over a wide range of angles of attack (α) ranging from 0° to 24° with an increment of 3° for three different Reynolds number in the order of 105. Results show a decrease in aerodynamic characteristics of the iced aerofoil when compared against the baseline clean wing configuration. The key flow field features such as point of separation, reattachment and formation of Laminar Separation Bubble (LSB) for different icing geometries and its influence on the aerodynamic characteristics are addressed. Additionally, attempts were made to understand the influence of Reynolds number on the iced-aerofoil aerodynamics.

A Study on the Prediction of the Aerodynamic Characteristics of a Launch Vehicle Using CFD (전산유동해석에 의한 발사체 공력 특성 예측에 관한 연구)

  • Kim Younghoon;Ok Honam;Kim Insun
    • 한국전산유체공학회:학술대회논문집
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    • pp.17-22
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    • 2004
  • A space launch vehicle departs the ground in a low speed, soon reaches a transonic and a supersonic speed, and then flies in a hypersonic speed into the space. Therefore, the design of a launch vehicle should include the prediction of aerodynamic characteristics for all speed regimes, ranging from subsonic to hypersonic speed. Generally, Empirical and analytical methods and wind tunnel tests are used for the prediction of aerodynamic characteristics. This research presents considerable factors for aerodynamic analysis of a launch vehicle using CFD. This investigation was conducted to determine effects of wake over the base section on the aerodynamic characteristics of a launch vehicle and also performed to determine effects of the sting which exist to support wind tunnel test model.

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A STUDY ON AERODYNAMIC CHARACTERISTICS DEPENDING ON SHAPE OF AN INTERNAL MOTOR IN A SIROCCO FAN FOR RESIDENTIAL VENTILATION (주거환기용 시로코홴의 내부모터 형상에 따른 공력특성 연구)

  • Cha, K.H.;Kim, J.H.;Kim, K.Y.
    • 한국전산유체공학회:학술대회논문집
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    • pp.321-326
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    • 2011
  • Aerodynamic characteristics depending on the shape of an internal motor in a small-size sirocco fan for residential ventilation have been investigated For the aerodynamic analyses of the sirocco fan, three-dimensional Reynolds-averaged Navier-Stokes equations are solved with the shear stress transport model for turbulence closure. The flaw analyses are performed on hexahedral grids using a finite-volume solver. The validation of the numerical results at steady-state is performed by comparing with experimental data for the pressure and efficiency. In order to investigate the aerodynamic characteristics depending on shape of an internal motor in a sirocco fan, the reference shape is analyzed compared to the case without internal motor. Additionally, two shape parameters, height and width of the internal motor in a sirocco fan, are tested to investigate their effects on the aerodynamic characteristics. The results show that the shape of the internal motor in a sirocco fan is an important factor to improve the aerodynamic performances.

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A STUDY ON AERODYNAMIC CHARACTERISTICS DEPENDING ON SHAPE OF AN INTERNAL MOTOR IN A SIROCCO FAN FOR RESIDENTIAL VENTILATION (주거환기용 시로코홴의 내부모터 형상에 따른 공력특성 연구)

  • Cha, K.H.;Kim, J.H.;Kim, K.Y.
    • Journal of computational fluids engineering
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    • v.16 no.4
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    • pp.1-6
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    • 2011
  • Aerodynamic characteristics depending on the shape of an internal motor in a small-size sirocco fan for residential ventilation have been investigated. For the aerodynamic analyses of the sirocco fan, three-dimensional Reynolds-averaged Navier-Stokes equations are solved with the shear stress transport model for turbulence closure. The flow analyses are performed on hexahedral grids using a finite-volume solver. The validation of the numerical results at steady-state is performed by comparing with experimental data for the pressure and efficiency. In order to investigate the aerodynamic characteristics depending on shape of an internal motor in a sirocco fan, the reference shape is analyzed compared to the case without internal motor. Additionally, two shape parameters, height and width of the internal motor in a sirocco fan, are tested to investigate their effects on the aerodynamic characteristics. The results show that the shape of the internal motor in a sirocco fan is an important factor to improve the aerodynamic performances.

A Numerical Study About the Aerodynamic Characteristics of Elliptic Airfoils (타원형 익형의 공력특성에 관한 수치적 연구)

  • Choe, Seong-Yun;Gwon, O-Jun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.2
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    • pp.1-10
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    • 2006
  • In the present study, the aerodynamic characteristics of elliptic airfoils are investigated numerically based on the RANS equations and the S-A turbulent model on unstructured meshes. Unlike the NACA series airfoil sections, elliptic airfoils have a relatively small leading edge radius and a rounded trailing edge. Also the maximum thickness is located in the middle of the chord. This geometric characteristics are responsible for the difference in the aerodynamic characteristics from those of NACA family airfoils. To identify the aerodynamic characteristics of elliptic airfoils, the results were compared with those of NACA series airfoils with a same maximum thickness. The effect of airfoil thickness variation on the aerodynamic characteristics were also investigated.

An Experimental Study of Aerodynamic Characteristics of the WIG under Accelerating and Decelerating Flows (지면효과익을 지나는 가/감속 유동의 공력특성에 관한 실험적 연구)

  • Kim, Tae-Ho;Yoon, Bok-Hyun;Kim, Heuy-Dong;Kashimura, Hideo
    • Proceedings of the KSME Conference
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    • pp.1939-1944
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    • 2004
  • Recently, several kinds of experimental and computational studies are being carried out to investigate the WIG aerodynamic characteristics which are of practical importance to develop the new ground transportation vehicle system. These works are mainly based upon conventional wind tunnel tests, but many problems associated with the WIG aerodynamic characteristics cannot be satisfactorily resolved due to the wind tunnel blockage effects or string problems to support the test object. To do this, it is necessary to develop a novel simulator appropriate to the WIG aerodynamics. The objective of the present study is to clarify the aerodynamic characteristics of a new developed WIG simulator, which is able to imitate real WIG flow circumstances such as gradually decelerating and accelerating flows.

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PREDICTION OF THE AERODYNAMIC CHARACTERISTICS OF AN ORBITAL BLOCK OF A LAUNCH VEHICLE IN THE RAREFIED FLOW REGIME USING DSMC APPROACH (DSMC 해석기법을 이용한 희박유동 환경에서의 발사체 Orbital Block 공력특성 예측)

  • Kim, Young-Hoon;Ok, Ho-Nan;Choi, Young-In;Kim, In-Sun
    • 한국전산유체공학회:학술대회논문집
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    • pp.79-82
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    • 2007
  • The aerodynamic coefficients of Apollo capsule are calculated using a DSMC solver, SMILE, and the results agree very well with the data predicted by NASA. The aerodynamic characteristics of an orbital block which operates at high altitudes in the free molecule regime are also predicted. For the nominal flow conditions, the predicted aerodynamic force is very small since the dynamic pressure is extremely low. And the additional aerodynamic coefficients for the analysis of the attitude control are presented as the angle of attack and the side slip angle vary from $+45^{\circ}\;to\;-45^{\circ}$ of the nominal angle.

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Changing Effect in Aerodynamic Characteristics of a Captive Body Separated from Aircraft (항공기 탑재체의 분리 후 공력 특성 변화 효과)

  • Cho, Hwan-Kee;Lee, Sang-Hyun;Kang, Chi-Hang
    • Journal of the Korea Institute of Military Science and Technology
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    • v.14 no.3
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    • pp.397-404
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    • 2011
  • The aerodynamic characteristics of a separated captive body in flow field around aircraft are studied to observe aerodynamic stability for safe separation from aircraft. Since the captive body separated from aircraft is initially exposed to unsteady flow pattern, the change of aerodynamic forces and moments should be measured to analyze how the flow pattern affects on the captive body at the vicinity of aircraft. Aerodynamic forces and moments of the separated captive body are measured at selected positions along predictable dropping trajectories. The measuring trajectories, generated by the free drop test of the dropping model in the wind tunnel, are consisted of 9 possible lines by free dropped trajectories. Experimental results show that the aerodynamic forces and moments are significantly varied with the distance between the captive body and aircraft. In conclusion, the change of aerodynamic characteristics within flow field around aircraft should be considered to simulate trajectories of the separated captive body from aircraft.