Velocity-Correction Formula for the Calculation of Transonic Mach Number Distributions Over Diamond-Shaped Airfoils

摘要

A velocity-correction formula is proposed for the purpose of calculating, from the known Mach number distribution for a diamond-shaped airfoil at a stream Mach number of 1.0, Mach number distributions on the same airfoil at speeds from a Mach number of about 0.8 to shock-attachment Mach number. The time required to calculate these additional Mach number distributions is small in comparison with the time required by rigorous methods. The accuracy of the results for stream Mach numbers near 1.0 is of the same order as the accuracy of the known Mach number distribution. Moreover, the results tend to become exact as the stream Mach number is increased toward that for shock attachment. An expression for the rate of change of local Mach number with stream Mach number is derived and an explicit equation for the drag coefficient as a function of stream Mach number and thickness ratio is given.