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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 1987, Vol. 8 ›› Issue (7): 327-334.

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AN ENGINEERING APPROACH FOR NEARLY SHOCK-FREE WING DESIGN

Zhu Ziqiang1, H.Sobieczky2   

  1. 1. Beijing Institute of Aeronautics and Astronautics;2. Deutche Forschungs-und Versnchsanstalt far Luft-und Raunfaht
  • Received:1986-02-25 Revised:1900-01-01 Online:1987-07-25 Published:1987-07-25

Abstract: Aerodynamic efficiency needs to be increased at transonic cruising speed with the constraints of desirable aerodynamic performance also at lower speeds. Reduced drag is obtained by avoiding flows with strong shock waves on the wing. A methdd to systematically change given shapes in order to arrive at shock-free flows and therefore obtain reduced drag is the "Elliptic continuation" or "Fictitious gas"method. But up to date the second step of this method has been used successfully only in the form of ill-posed space-marching methods for swept wings with high aspect ratio and low swept angles. It has been already observed and understood; that aerodynamic efficiency is optimal not at shock-free conditions, but at somewhat higher Mach number and lift coefficients than those used for design. In the present paper, we use a reliable transonic analysis algorithm with an analytic fictitious gas model to develop a simplified version of the design method which does not aim 'oward finding exactly shock-free flows but such ones with possibly only weak shocks. In this method, we use the transpiration velocity boundary condition rather than the space-marching procedure to simulate the surface deformation. As shown in the numerical example this procedure yields almost shock-free configurations.