Turbulent Tunnel PDF Download

Summary: The effect of Reynolds number on the aerodynamic characteristics of a low-drag airfoil section tested under conditions of relatively high stream turbulence was determined by tests in the LMAL 7- by 10-foot tunnel of the NACA 653-418, a = 1.0 airfoil section with a split flap having a chord 20 percent of the airfoil chord. The Reynolds number ranged from 0.19 to 2.99 x 106; the Mach number attained was never greater than 0.10. The data are presented as curves of section angle of attack, section profile-drag coefficient, and section pitching-moment coefficient against section lift coefficient for various flap deflections. The maximum lift coefficient increased with Reynolds number. Deflecting the flap added an increment of maximum lift coefficient that seemed to be almost constant at all Reynolds numbers. The slope of the section lift curve with flap deflected showed no consistent variation with Reynolds number, although the slope of the section lift curve for the plain airfoil increased up to a Reynolds number of about 1.0 x 10 6 and then remained nearly constant up to a Reynolds number of about 3.0 x 106, the limit of the tests. For flap deflections about 15°, the slope of the section lift curve decreased with increase in flap deflection. The section drag coefficient with flap deflected remained almost constant with Reynolds number of about 0.8 x 106 and then remained nearly constant to a Reynolds number of about 3.0 x 106.