Gravity flow of granular materials in vertical columns can generate pressure and density fluctuations which are difficult to quantify. Examination of prior research led us to propose a new measurement technique based on the principle of pulse induction (PI) for metal detection. An experimental device using 8 mm diameter spherical particles flowing through a polyvinylchloride (PVC) pipe of 75 mm diameter and 1000 mm height was developed to demonstrate the feasibility of PI. Ten PI coils were used to quantify tracer movement through the column with time. Average and instantaneous velocities were determined for five diameters of outlet orifices: 68.0, 62.5, 54.5, 44.0 and 36.5 mm. Flow rate was calculated and modelled. When compared to prior research, PI proved to be a reliable method for flow measurement in opaque ducts.
Meziane, Nasreddine, Bettahar, Ahmed, Choudhary, Ruplal and Watson, Dennis G. "Measurement of granular flow in a vertical column using pulse induction (PI)." Biosystems Engineering 114, No. 2 (Feb 2013): 78-85. doi:10.1016/j.biosystemseng.2012.11.009.