The effect of a flow corrective insert upon flow patterns and wall stresses in a two-dimensional bin-hopper

摘要

The flow patterns and stresses on the wall in a two-dimensional bin-hopper with the placement of an equilateral triangle flow corrective insert were investigated.The geometric shape and location of five kinds of equilateral triangle insert used in this study were obtained using the method previously proposed by Johanson.The flow pattern histories of the quartz sand in the bin-hopper were recorded using a digital camcorder.The static wall stress distributions above the insert produced by the quartz sand were measured.The variations in the dynamic wall stresses with time were obtained.As the insert half-angle increased,the region of the quasi-stagnant zone,which sat on the equilateral triangle insert,became larger and the position of the static normal stress peak moved downward.In general,the values of the dynamic normal wall stress measured by the pressure gauge,which was not close to the insert,were smaller than those under the test without the placement of an insert during the most part of material withdrawal.Nevertheless,some of the dynamic normal wall stress peaks were measured by the pressure gauge,which was close to the insert,as the insert half-angle was between 30deg and 50deg.