Effect of Flow Rate Parameters on Eccentric Cylindrical DMA Transfer Function

Cylindrical differential mobility analyzers (DMAs) are fundamental instruments for submicron aerosol characterization; however, their sizing precision is highly susceptible to manufacturing and assembly imperfections, particularly electrode eccentricity. This study systematically investigates the coupled effects of flow rate parameters and axial eccentricity on the DMA transfer function. Building upon established theoretical frameworks developed by Alsharifi and Chen (Aerosol Science and Technology 2019a), we analyze how structural misalignment degrades classification resolution. The numerical model was rigorously validated against experimental and computational results from Chen et al. (1998) and Alsharifi and Chen (2019a, b). Our findings reveal that while the total flow rate remains invariant to eccentricity, electrode misalignment induces a detrimental shift toward a bimodal transfer function. Crucially, we demonstrate that strategic optimization of the flow rate ratio can significantly suppress this resolution degradation and mitigate the bimodal shift. This research provides essential theoretical insights and practical guidelines for tuning operational parameters, ultimately enhancing the sizing accuracy and reliability of DMAs in high-precision aerosol measurements.