What are the main methods of angle of repose measurement?

There are two methods for measuring the angle of repose. One is the injection angle, which refers to the angle of repose formed when powder is injected from a certain height onto an infinite flat plate. The other is the exclusion angle, which refers to the angle of repose when powder is injected into a certain height. On a circular plate with a finite diameter, when the powder accumulates to the edge of the circular plate, the powder begins to be discharged from the edge. At this time, the accumulation angle formed by the powder on the circular plate is the discharge angle.

The diameter of the bottom layer of powder accumulation cannot be too large. If it is too large, the accumulation surface below will be compressed by its own weight, and the angle of repose will change significantly. However, the diameter of the bottom layer cannot be too small. If it is too small, the injection angle will become larger. It is generally 10cm. as well.