Calculated Calibration Curves for Particle Size Determination Based on Time-of-Flight (TOF)

ABSTRACT

A model based on the equations for particle trajectory in a supersonic, one-dimensional, compressible flow was developed. The model was used to provide calibration curves for determination of particle size for time-of-flight instruments. In this study, particle trajectory calculations were performed for an Aerosizer (a time-of-flight (TOF) particle size determination instrument) using various expressions for drag coefficient obtained from the literature and considering that particle drag is a function of particle Reynolds number, Mach number, and gas properties in a supersonic flow field. The time-of-flight was calculated between the two laser beams in the instrument downstream of the nozzle and compared with recent experimental data (Cheng et al., 1993) in the literature, to develop the model and provide new calibration curves. The new calibration curve provide TOF values comparable to experimental value (2.4% to 4.4%). The original calibration curves from the manufacturer provides value between 35% to 60%.