Comparative Study of Square and Sine-Wave Excitation Methods for the Measurement of Aerosol Particles Charge and Size Distribution Using Phase Doppler Anemometry

This paper describes and compares two particle excitation methods, square and sine wave, used in conjunction with an application of phase Doppler anemometry to simultaneously obtain particle size and charge in real time. Different signal-processing strategies for particle velocity and size estimation are investigated, including quadrature demodulation, spectral analysis, and correlation technique. The systems performance has been tested using Monte Carlo simulations obtained from the synthesized Doppler burst signals. A mathematical model has been developed to estimate the percentage of particles captured in the measurement volume and successfully analyzed by the signal-processing system, leading to the optimization of the system parameters. Finally, some preliminary experimental results are given. It can be concluded that the measurement system using the square-wave excitation and based on the spectral analysis performs better in terms of the measurement range, SNR requirement, and particle capture efficiency.