Experimental study of the effect of the chamber radius on the bifurcation value of the drum rotation speed during self-excitation of monograin intrachamber filling auto-oscillations

The aim of the study is to experimentally establish the influence of the radius of the rotating drum chamber R on the value of the bifurcation rotation speed ω b i f during self-excitation of auto-oscillations of a single-grain intra-chamber filling. The criterion modeling method based on visualization of the filling behavior was applied. Eight variable drums with a chamber radius R = 18.75-212 mm were used. To represent the desired dependence in the criterion form, a bifurcation diagram R e , F r was used in the axes of the dynamic criteria for the similarity of the flow on the cylindrical surface of the rotating drum chamber. An analogue of the Reynolds number was used based on the identified analogue of the granular kinematic viscosity of the liquefied granular filling. The influence of R on ω b i f was estimated by the position of the bifurcation line F r b i f R e b i f on the diagram. The scientific novelty of the work lies in establishing the increase in the bifurcation value of the Froude number F r b i f with increasing R . It was also found that F r b i f decreases with increasing the degree of filling of the chamber. The results obtained allow us to predict the parameters of the implementation of innovative energy-efficient auto-oscillating processes for processing granular materials with a variation of the drum radius.