Analytical comparisons of electrostatic sensors with various geometric probes for gas path monitoring

Various electrostatic sensors have been widely used for detecting abnormal debris present in gas path from fault. The sensor geometries have important effects on their sensor sensitivity. In this paper, the sensing features of three typical sensors, i.e. circular thin-plate-shaped sensors, hemisphere-shaped sensors and special rod-shaped sensors, are compared theoretically by analytical functions to find their advantages and limitations. In particular, an analytical function of a special rod-shaped sensor is proposed to provide corresponding sensing characteristics for the first time. The numerical simulations precisely show the compared sensing features of these sensors in terms of spatial sensitivity. The results demonstrate that the special rod-shaped sensor has given rise to strongest signals, while it affects the gas flow. Conversely, the circular thin-plate-shaped sensor is totally non-intrusive. Moreover, the hemisphere sensor as a tradeoff between two other sensors has intermediate signals and causes fewer gas flow disturbance. They are capable of meeting different requires of various applications.