Spatial filtering characteristics of electrostatic sensor matrix for local velocity measurement of pneumatically conveyed particles

The accuracy of local particle mean velocity measurement with spatial filtering method based on an electrostatic sensor matrix (ESM) is closely related to its sensitivity and spatial filtering characteristics. In this paper, the three-dimensional electrostatic field generated by a point charge in the sensing zone of the ESM is solved by using a finite element method to obtain the spatial sensitivity distributions of the ESM. Further a dimensionless calculation model for the sensitivity of the ESM is suggested based on a Cosine function. The numerical results demonstrate that the spatial sensitivity has a periodic distribution along the axial direction and its spatial periodicity is determined by the axial spacing between two adjacent electrodes. The sensitivity over the central cross-section is localized. The spatial filtering characteristics of the ESM are also investigated and verified by experiments on a gravity-fed rig. These results provide a basis for the optimized design of the ESM.