Shock Tube Determination of the Drag Coefficient of Small Spherical Particles
An experimental study was conducted to determine the drag coefficient of inert spherical particles accelerating in a laminar, non-reacting, incompressible continuum flow. The Reynolds number range which was covered in the study was from 150 to 1700, and particle sizes ranged from 150 JL to 450 JL. The convective flow behind the shock wave in a shock tube was used to accelerate the particles. The particle's diameter and the displacement versus time measurements were obtained using a rotating drum camera in conjunction with an oscillating light source. The photographic data, the particle density, the shock speed, and the initial pressure and temperature in conjunction with the normal shock relations were combined to calculate the drag coefficient. The drag coefficient is usually considered to be a function only of Reynolds number and acceleration modulus, however, CD varies considerably because of particle roughness. Experiments with HP 295 ball powder, whose surface is relatively rough, produced results which were as much as 85 per cent higher than the steady state curve, with the increase dependent upon the relative Mach number of the flow about the particle. Similar drag coefficient experiments with smooth sapphire balls did not produce the scatter, the higher values, nor the dependence on relative Mach number.
B. P. Selberg, "Shock Tube Determination of the Drag Coefficient of Small Spherical Particles," Michigan State University, Jan 1966.
Mechanical and Aerospace Engineering
National Aeronautics and Space Administration
Keywords and Phrases
Aerodynamic Drag; Particles; Coefficients; Mach Number; Laminar Flow; Reynolds Number; Incompressible Flow; Shock Tubes
© 1966 Michigan State University, All rights reserved.
01 Jan 1966