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Effect of net surface charge on particle sizing and material recognition by using phase Doppler anemometry
1Key Laboratory of Mechanics on Disaster and Environment in Western China, Lanzhou University, Ministry of Education, Lanzhou, Gansu 730000, China. zhoujun@lzu.edu.cn
Applied Optics
|January 26, 2011
Summary
Net surface charge significantly impacts particle sizing and refractive index measurements using phase Doppler anemometry (PDA). This study introduces a method to identify charged particles and determine their surface conductivity for accurate PDA analysis.
Area of Science:
- Optical Particle Characterization
- Applied Electromagnetics
- Fluid Dynamics
Background:
- Phase Doppler Anemometry (PDA) is a widely used technique for measuring particle size and velocity.
- The presence of net surface charge on particles can influence light scattering, potentially affecting PDA measurements.
- Accurate particle characterization is crucial in various fields, including aerosol science, combustion, and spray analysis.
Purpose of the Study:
- To investigate the effect of net surface charge on particle scattering fields and PDA measurement parameters.
- To analyze the influence of surface charge on the phase-diameter relationship and phase ratio in PDA.
- To develop a method for recognizing charged particles and estimating their surface conductivity using PDA.
Main Methods:
- Mie's theory was employed to compute the scattering field of charged particles illuminated by dual laser beams.
- The study analyzed the phase-Doppler relationship and phase ratio as functions of particle properties and surface charge.
- A novel approach was proposed to identify charged particles and determine surface conductivity based on observed PDA measurement deviations.
Main Results:
- The net surface charge was found to significantly alter the phase-diameter relationship compared to uncharged particles.
- The relationship between the phase ratio and the refractive index of charged particles deviates notably from that of neutral particles.
- These deviations can lead to substantial errors in particle sizing and refractive index determination.
Conclusions:
- Net surface charge is a critical factor that must be considered for accurate particle characterization with PDA.
- The proposed method enables the identification of charged particles and the quantification of their surface conductivity.
- This research enhances the reliability of PDA measurements in environments with charged particles.
