Aerofoil incidence for zero lift in subsonic two- dimensional flow.
Abstract:ESDU 98011 gives a method for predicting the viscous zero-lift incidence of aerofoils. The method applies to aerofoils with simple or complex camber lines and accounts for the effect of compressibility, but is limited to subcritical flows. The boundary layer thicknesses at the trailing edge increase the zero-lift incidence above that predicted by inviscid theory. The method of Pankhurst is used to calculate the inviscid zero-lift incidence and two simple factors presented graphically are used to correct that value for the effects of viscosity and compressibility; both depend on the camber-line geometry in the vicinity of the trailing edge and Reynolds number while the latter also depends on Mach number. The VGK program was applied to a selection of aerofoils with a wide variety of camber-line shapes to derive the factors. The method applies to fully-attached flow and will therefore be unreliable for aerofoils with excessive thickness or camber. The accuracy of prediction of the viscous zero-lift incidence is within 0.2 degrees. Worked examples illustrate the use of the method.
|Data Item ESDU 98011|