APPENDIX 3 NOTES ON ELECTROSTATIC PRECIPITATOR By H. J. uiuiova 1. Laws of Motion of Small Particles Subjected to a Porce (a) A small particle subjected to a force 4g accelerated thrpugh the mecis e particles of in the surrounding space, the resulting motion through the media results in a resistive force to the motion giwen by Stokes a3 R ® (1) kdv «a Yor spheres k * 377. When the velocity through the medial that the resistive force is equal to the accelerating f acceleration will be sero resulting in a constant veloc the terminal velocity. () is such e, the y terned For a spherical particle in a gravitational field , . 1 P 3 mg; ni 4783p z z TB >p The terminal velocity will remilt when PF = Ror i 1rd Pp 8 317d vps a @ (2) ory © 18 (c) Tf the perticle acquires an eleetrical charge and is in trical f4eld the force on the particle will be F = an elec- QE The terminal velocity will then be Qt 377 4 - (a) (3) For particles of a size approaching the mean free path of air molecuiss, a correction dus to Cunningham is required $ account for the additional velocity caused by the particle acc between impacts. This is given by v * Yerokes Q + ky >») -77UNCLASSIFIED erating (h) 00131986 069