傾斜とい内を流れる粒体の速度分布について
1971 年 20 巻 213 号 p. 773-775
詳細
1971 年 20 巻 213 号 p. 773-775
The phenomena of gravity flow of bulk solid has hitherto been investigated through the flow in a hopper or a rotary cylinder, but the flow in such a device is complicated too much to clarify the flow characteristics of bulk solid precisely.
As it is considered that an inclined open channel for observing the flow of bulk solid is relatively simple, the flow behavior of grains of rapeseed was studied within an inclined open channel.
The channel is made of a transparent acryl plate of 5mm in thickness, into size 940mm in length, 50mm in width, and 80mm in depth. Barnyard millet was mixed into the rapeseeds as tracer in the ratio of one to twenty-five (1 to 25).
A photographic observation of the channel was carried out by means of a stroboscope in three directions within the range of 530∼580mm from the inlet of the channel. The slope of the channel was set at 23.0°, 27.5°, 31.5°, or 35.5°.
The velocity distribution curve obtained through the side wall was nearly linear except in the neighbourhood of the bottom. When the slope of the channel was 23.0°, the distribution curve showed the shape of the letter S. This is considered to be due to the fact that the slope of the channel was smaller than the angle of repose, 24.5°, of the specimen.
The velocity of the flow at the surface and that at the bottom showed the maximum value in the middle part of the channel as it was the case with viscous fluid, and the boundary layer was developed near the side wall. The distribution curves were approximately quadratic.
Regarding the distribution curve of the side wall as a line, the flow rate and average velocity can be calculated on the basis of the velocity distribution curves of surface and bottom and the area of cross section of granular layers, and the average velocity has been found as about 80% of the maximum velocity.
The average porosity in flowing has been estimated upon the calculated value of the flow rate and the measured value of the mass flow rate, and has been found as smaller than the porosity of the sphere model in the cubic arrangement.
