Fluid Mechanics and Flight Mechanics

Rotor/Empennage Unsteady Aerodynamic Interaction with Unsteady Panel/Viscous Vortex Particle Hybrid Method

  • TAN Jianfeng ,
  • WANG Haowen ,
  • WU Chao ,
  • LIN Changliang
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  • 1. School of Mechanical and Power Engineering, Nanjing University of Technology, Nanjing 211816, China;
    2. School of Aerospace, Tsinghua University, Beijing 100084, China;
    3. College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;
    4. Institute of Aircraft Design, AVIC Harbin Aircraft Industry Group Corporation, Harbin 150066, China

Received date: 2013-04-27

  Revised date: 2013-06-27

  Online published: 2013-07-19

Abstract

The unsteady aerodynamic interaction of the rotor and empennage of a helicopter is the main cause of the "Pitch-up" phenomenon in helicopter flight dynamics. To accurately predict the rotor/empennage unsteady aerodynamic interaction and the variation of transverse handling characteristics caused by it under low-speed flight in the helicopter design phase, an unsteady panel/viscous vortex particle hybrid method is established through the equivalence of vorticity and Neumann boundary conditions. The unsteady aerodynamic loads of a rotor blade and empennage are described by the unsteady panel method while the rotor time-varying effect and the viscous and stretch effect of the rotor wake are represented by the viscous vortex particle method, and the interaction of the rotor wake and empennage is implemented through a vorticity mirror method. The rotor wake and induced velocity distribution of NASA ROBIN (Rotor Body Interaction) are predicted and compared with experiment, time-accurate free-wake and CFD results. It demonstrates that the present method is more accurate than the free-wake method. The effect of rotor wake/empennage unsteady aerodynamic interaction on empennage airloads is then analyzed, and the influence of empennage type on rotor wake/empennage aerodynamic interaction is also studied. It is shown that rotor wake/empennage aerodynamic interaction leads to an abrupt increase of empennage airloads and the reversal of aerodynamic derivatives in low-speed flight. The increase of low-set empennage's airload is relatively large, while that of high-set empennage is small, and the reversal of aerodynamic derivatives for high-set empennage occurs in high speed. Although the increasing of forward-set empennage airload is small, the range of speed is wide. Increase of the right-set empennage airload for right-handed rotor is small, but the derivative is similar to that of the left-set empennage.

Cite this article

TAN Jianfeng , WANG Haowen , WU Chao , LIN Changliang . Rotor/Empennage Unsteady Aerodynamic Interaction with Unsteady Panel/Viscous Vortex Particle Hybrid Method[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2014 , 35(3) : 643 -656 . DOI: 10.7527/S1000-6893.2013.0324

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