Measurement of density and mass flow of particles in a dilute suspension in general flow

Abstract

For the measurement of density and mass flow of the particle phase in an air suspension in pipe flow with tangential motion, new instrumentation, needs arose. For these measurements, the earlier fiber optics probe and electrostatic ball probe have to be modified. Simultaneous measurements of particle density and mass flow permits determination of mean velocity of the particle phase. For the measurement of particle density, a ‘twin diode’ optical probe has been introduced. In this design, the source and detector are two miniature diodes, one as a source and the other as a detector mounted on two arms of a probe holder. The probe is insensitive to yaw angles of ±90° and pitch angles of ±30°. The probe sensitivity approaches 0.01 kg/m 3. An important innovation of the electrostatic counter probe is by filtering and counting the electric pulses of particles impacting on a probe due to charge transfer. The probe diameter can be as small as 1.6 mm. Sensitivity of the order of 0.002 kg/m 2 s has been indicated. This probe is insensitive to direction of motion of particles and has potential for use in fluctuating or nonsteady flows.