• Title/Summary/Keyword: Aerodynamics

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Aero-optical effects in the hypersonic flow field

  • Shi, Ketian;Miao, Wenbo;Li, Pengfei;Chen, Xiaoli
    • International Journal of Aerospace System Engineering
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    • v.2 no.1
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    • pp.12-17
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    • 2015
  • Aero-optical effects induced by the flow around the optical window degrade the performance of the IR seeker, especially for the hypersonic flow. For the thermochemical non-equilibrium flow, index of refraction model and optical transmission calculation method are developed to predict the aero-optical effects. The optical distortion is discussed for the typical optical widow shape and flow condition. The influence on aero-optical effects is analyzed.

INVESTIGATION FOR THE AERODYNAMIC CHARACTERISTICS OF HIGH SPEED TRAIN PANTOGRAPH WITH COVER (커버 형상을 고려한 고속전철 팬터그래프 공력특성의 수치해석적 연구)

  • Kang, H.M.;Kim, C.W.;Cho, T.H.;Kim, D.H.;Yoon, S.H.;Kwon, H.B.
    • Journal of computational fluids engineering
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    • v.17 no.3
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    • pp.18-24
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    • 2012
  • The aerodynamic performance of the pantograph on a high speed train was compared for different pantograph covers which are designed to block the aero-acoustic noise from the pantograph. For the study, two types of cover are designed: wedge and cone types. The lift force of pantograph with cover was compared with the force of pantograph only. The comparison clarified that the cone type cover increases the sideslip angle of the flow and decreases the lift force considerably. However, the wedge type cover changes the flow direction upward and increases the lift force of the pan head. This increment of lift force compensates the decrement of lift force caused by the blocking of the flow into the pantograph lower frame due to cover. Therefore, in case of the wedge type cover, the overall lift force changes slightly compared with the cone type cover.

Hypersonic Aero-Heating Ground-Test Simulation Technique

  • Li, Ruiqu;Yao, Dapeng;Sha, Xinguo;Gong, Jian
    • International Journal of Aerospace System Engineering
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    • v.2 no.2
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    • pp.50-53
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    • 2015
  • It would encounter some complicated flow fields, such as transition, separation, reattachment and disturbances, in the hypersonic flight. Thus, it is difficult to theoretically analyze the hypersonic aerothermodynamics effects, so that the ground-test simulation is thought of as one of the most important methods to improve the understanding level of the hypersonic aerothermodynamics. However, the aero-heating tests could not simulate all aerodynamics and geometry parameters in the real flight due to the differences between the experimental environments supplied by the ground facilities and the flight, so that the feasible technique for the ground-test simulation of the hypersonic aerothermodynamics effects is required to be advanced. The key parameters that are especially required to simulate for aero-heating tests are analyzed and one detailed approach is suggested to perform the experimental investigation on the hypersonic aero-heating effects in the ground facilities in this paper, and the tests are performed in the FD-20 gun tunnel of CAAA (China Academy of Aerospace Aerodynamics) to give out the data which could be used to confirm the equation from the theoretical analysis.

An Unstructured Mesh Technique for Rotor Aerodynamics

  • Kwon, Oh-Joon
    • 한국전산유체공학회:학술대회논문집
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    • 2006.10a
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    • pp.24-25
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    • 2006
  • An unstructured mesh method has been developed for the simulation of steady and time-accurate flows around helicopter rotors. A dynamic and quasi-unsteady solution-adaptive mesh refinement technique was adopted for the enhancement of the solution accuracy in the local region of interest involving highly vortical flows. Applications were made to the 2-D blade-vortex interaction aerodynamics and the 3-D rotor blades in hover. The interaction between the rotor and the airframe in forward flight was investigated by introducing an overset mesh technique.

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Aero-optical transmitting effect in the compressible mixing layer

  • Ma, Handong;Gan, Caijun;Li, Lang
    • International Journal of Aerospace System Engineering
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    • v.2 no.2
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    • pp.79-82
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    • 2015
  • The handicap for investigating the aero-optical effect focuses on the accurate prediction on the index refraction fluctuation or density fluctuation. In recent years, with the development of CFD techniques and optical experimental techniques, the comprehension have developed on the aero-optical transmitting effect in many kinds of complex flow. This study mainly introduces the optical aberration in compressible mixing layer. And then the debates about the mechanism of aero-optical effects and assessment of image blur also present.