DRAG OF CIRCULAR CYLINDERS NORMAL TO A FLAT PLATE WITH A TURBULENT BOUNDARY LAYER FOR MACH NUMBERS UP TO 3.

ESDU 83025 provides a method of predicing the drag due to circular cylinders mounted on a flat plate with a turbulent boundary layer for Mach numbers up to 3. It applies to such items as drain masts, whip aerials, ill-fitting access hatches, fasteners etc. The complexity of the flow around a circular cylinder and its variation with geometry is such that no single drag prediction method could be expected to represent all possible geometries and flow conditions. However, the availability of sufficient quantities of experimental data allowed provision of empirically-based methods for two ranges of cylinders. The first method caters for any cylinder whose height is not less than its diameter. It applied to cylinders either wholly or partially immersed in the boundary layer at free-steam Mach numbers up to 3. The second method caters for any cylinder whose height is small compared with its diameter and the boundary layer thickness, but applies only to low-speed flows. The two methods are comparable in terms of expected accuracy; the available experimental data are correlated generally to within about 0. 05 in C//D based on the frontral area of the cylinder. A worked example for each method is given to illustrate typical uses of the Item.