Measurement System Based on Electrostatic Sensors to Detect Moving Charged Debris with Planar-Isotropic Accuracy

We present a measurement system capable to detect and reconstruct the trajectory of moving charged debris expelled with the exhaust gases or circulating in the lubricating oil of engines, aero-engines, or gas turbines. The measurement technique is based on a circular array of three electrostatic sensors used to estimate the trajectory, the charge, and the velocity of a moving charged particle. We discuss methods to process the information provided by the sensors, combining physical models and the geometrical characteristics of the sensor array, providing a theoretical characterization of the measurement accuracy, which is shown to be not dependent on the direction of the particle motion with respect to the sensor placement. The information obtained with the measurement system can be used to reject false positives when the sensors and the front-end electronics are used in noisy environments

Electrostatic Sensors – Their Principles and Applications

Over the past three decades electrostatic sensors have been proposed, developed and utilised for the continuous monitoring and measurement of a range of industrial processes, mechanical systems and clinical environments. Electrostatic sensors enjoy simplicity in structure, cost-effectiveness and suitability for a wide range of installation conditions. They either provide unique solutions to some measurement challenges or offer more cost-effective options to the more established sensors such as those based on acoustic, capacitive, optical and electromagnetic principles. The established or potential applications of electrostatic sensors appear wide ranging, but the underlining sensing principle and resultant system characteristics are very similar. This paper presents a comprehensive review of the electrostatic sensors and sensing systems that have been developed for the measurement and monitoring of a range of process variables and conditions. These include the flow measurement of pneumatically conveyed solids, measurement of particulate emissions, monitoring of fluidised beds, on-line particle sizing, burner flame monitoring, speed and radial vibration measurement of mechanical systems, and condition monitoring of power transmission belts, mechanical wear, and human activities. The fundamental sensing principles together with the advantages and limitations of electrostatic sensors for a given area of applications are also introduced. The technology readiness level for each area of applications is identified and commented. Trends and future development of electrostatic sensors, their signal conditioning electronics, signal processing methods as well as possible new applications are also discussed