Characteristics of mass flow rate of granular material in an inclined open channel attached under a hopper were investigated. The flow layers near an adjusting sluice valve were formed of three layers, that is, steady flow, intermittent flow and reposing layer from the surface. Mass flow rate was increased according to the opening height of the valve. However, increasing ratio of mass flow rate became suddenly small, as the valve opening up to some height. The cause was that the intermittent flow layer attained undr the valve. Mass flow rate of granular material in a range of the large increasing ratio was expressed as follows: G=Kρ_bB^3/2(h-h₀)(gsinθ)^1/2 where G is mass flow rate, ρ_b is bulk density, B is width of the channel, h is opening height of the valve, h₀ is loss opening height of the valve by contracted flow, g is gravity acceleration, and K is constant that depends on characteristics of granular material, width and inclination angle θ of the channel to horizontal plane.

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In many cases granular materials in a storage vessel are discharged through an attached chute. In this study, the effects of the properties of materials, the dimensions of the opening of the bin outlet, the inclined angle and the breadth of the rectangular open channel attached as a chute to the side of the rectangular bin on the flow rate of granular materials are investigated. Glass beads and sand are used as granular materials.
In conclusion, the flow rate of granular materials from a rectangular bin is expressed as a function of the properties of particles and the dimensions of the opening of the bin outlet. When an open channel is used as a chute, the flow rate of granular materials becomes lower compared with that for no chute. It increases as the inclined angle of the open channel increases. Qualitatively it is found that the flow rate depends upon the flow pattern of particles in the open channel.

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