Nikolay Bragin, Mansur Garifulin, Sergey Skomorokhov, Vitaliy Yanin

DOI Number: N/A

Conference number: IFASD-2015-038

The lift coefficient of buffet onset (CLb) or buffet boundaries is one of those limitations that should be taken into consideration when developing aerodynamic design of the subsonic aircraft wing, starting from the conceptual design stage. At cruising (transonic) Mach numbers pressure oscillations, leading to buffet load, are preconditioned by interacting shocks and the boundary layer of the wing. These oscillations are associated with fluctuations in flow separation zones, positions and shocks intensity. A certain problem comes with predicting СLb value by results of models test in a wing tunnel and transferring results on to a full-sized aircraft. In most cases, WT tests of full scale models are conducted at Reynold’s numbers (calculated by the average aerodynamic wing chord) no more than Re = (2.5-4.5) million. At these Reynold’s numbers the wing with free transition of the boundary layer may include large segments of the laminar boundary layer which influence shocks position and buffet origination. With fixed transition of the boundary layer it becomes thicker if compared to real aircraft flight conditions. In this case buffet development will also differ from real conditions. This paper investigates peculiarities of influence of Reynold’s number and of the boundary layer state on characteristics of flow about high aspect ratio wing at AoA up to buffet development.

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In Categories: 2. IFASD 2015, Experimental Methods & Bridges
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