ESDU 78019:2014

ESDU 78019 gives a correlation of computed results using a
method that allows iteratively for the displacement effects of the
boundary layer and wake. It is found that by plotting the profile
drag of the body as a fraction (the form factor) of the skin
friction on a flat plate with the same transition position at the
same Reynolds and Mach numbers, the data can be correlated and
shown graphically simply as a function of body geometry parameters
for a datum condition of transition at the nose, zero Mach number
and fixed Reynolds number. Correction factors, also given
graphically, correct the data for different transition positions
and Mach numbers from datum. To assist in obtaining the value of
profile drag, additional graphs give the flat plate mean skin
friction for an appropriate range of transition positions, Reynolds
numbers and Mach numbers. The method of correlating the data has
been found to be accurate within 1 per cent for a range of body
geometry and flow conditions. The computational method itself was
found to agree within 5 per cent with a limited number of reliable
experimental data available in the literature. A worked example
illustrates the use of the data. ESDU 77028 gives, for a range of
forebody and afterbody shapes, the geometry parameters required for
the use of the correlation.

Although the method is relatively simple to apply, it is fairly
time consuming to evaluate by hand due to the need to determine
some second-order effects of body geometry. Analytic equations were
therefore developed using the original database, producing a
simplified method given in Addendum A. The equations are easily
programmed and give a correlation only marginally worse than the
graphical method and, moreover, they extend the method to cover a
greater range of transition positions. Tentative provision is also
made for bodies of smooth non-circular cross section. A computer
program of the simplified method is provided as ESDUpac A7819.