ESDU 06001 provides simple equations and graphs for predicting the skin friction drag coefficient for symmetrical and cambered aerofoil sections with smooth surfaces and attached flow@ in the presence of a pressure field@ with fixed boundary-layer transition on both upper and lower surfaces. The predicted value is that occurring at zero lift@ which is also representative of the skin friction drag coefficient at other low values of lift coefficient when boundary-layer transition is fixed. The method is based on correlating results of calculations made with the VGK Computational Fluid Dynamics program which iteratively allows for the effect of boundary-layer thickness in deriving the pressure distribution around the aerofoil at subsonic Mach numbers. The VGK program calculates skin friction drag coefficient using an empirical expression employing the known surface pressure distribution. The method provides an equation for the skin friction drag coefficient in incompressible flow as a function of an equivalent aerofoil thickness parameter@ transition position and Reynolds number. An equation gives a factor to be applied to that prediction to allow for the effect of compressibility at higher Mach numbers. Graphs obtained by plotting the equations provide an alternative prediction method. The accuracy of the method is discussed and the ranges of the parameters for which it was developed are tabulated. Plots of predictions by the method against the VGK data show a correlation to within two drag counts over the full range of Reynolds number and Mach number. A worked example illustrates the use of the method.
ESDU 06001-2006 history
2006ESDU 06001-2006 Aerofoil skin friction drag for Mach numbers below the drag-rise condition.