Static and dynamic pressure measurements of maize grain in silos under different conditions

Abstract

Silos are used worldwide to store products of high commercial value. However, many questions remain unanswered regarding storage and estimation of pressures in silos. Furthermore, there are few full-scale experimental stations in the world to facilitate the study of silo pressures, hindering progress in this area. The aim of this paper is to describe the setup, calibration, and validation of a pilot-scale test facility. The pilot silo described here contains 59 measurement cells capable of measuring loads and pressures throughout the silo. In addition, it can be used to study maximum and dynamic pressures in the filling, static, and discharge phases using a range of stored products. Validation of this test facility using maize yielded reliable and novel results, which were compared with Eurocode 1, part 4 (CEN, 2006). Pressures were obtained in the pilot silo at two different grain heights: 2.77 m and 5.30 m, and were evaluated in all three filling, static, and discharge phases. Normal and friction pressures in the silo, vertical stress at the silo–hopper transition, product weight, flow rate, and test time were recorded. The results obtained were consistent with the standard and the findings reported in other studies, demonstrating the accuracy of the pilot silo calibration and thus validating the experimental model. Some of the novel findings obtained include the moment of maximum pressure at the transition during discharge and the influence of silo slenderness on settling of the material during filling and under static conditions. • Product accommodation is influenced by the slenderness of the silo. • The moment of maximum pressure in the transition is influenced by the slenderness. • The slenderness of the silo influences the moment of the maximum friction pressure. • The greater the slenderness of the silo, more maximum normal pressure points. • Normal and friction pressures on the wall are influenced by slenderness.