Motion of tracer particles in supersonic flows

Factors that may act on particle motion in high-speed flow are investigated . The classical expressions of drag coefficient C-D for a sphere are review ed. Then, a drag expression is proposed, extending Cunningham's method to h igher velocities and Knudsen numbers. This law, valid from continuum to fre e molecule conditions, for Re less than or similar to 200 and M less than o r similar to 1 (where Re and M are, respectively, the Reynolds and Mach num bers based on relative velocity), is used to compare calculated and experim ental values of the drag coefficient, as well as the particle velocities ac ross an oblique shock wave. Calculated results are found to be in agreement with experiments.