POA * ONLINE SUBSCRIPTION ONLY

ESDU 75031 gives an empirical method for the prediction of the drag increment due to a variety of two-dimensional excrescences, each mounted normal to the flow direction on a flat plate, and immersed in a turbulent boundary layer for Mach numbers up to 3. The excrescence types are

i) a forward-facing step, ramp (chamfered step), or a radiused step,

ii) a rearward-facing step, ramp (chamfered step), or a radiused step,

iii) a square section ridge or a rectangular section ridge (of height/length ratio 2), with or without radii to the top corners.

Two compatible versions of the method are given. The first involves the use of graphs to determine the parameters used in the evaluation of the necessary empirical equation. The second version, details of which are given in Appendix A, involves the use of tabulated data only, obviating the need for graphical information.

A computer program of the method is provided as ESDUpac A7531.