Vibrationally aided flow of lunar regolith simulants in a hopper-based conveying device

Hoppers are expected to play an essential role in handling of lunar regolith for future lunar exploration missions from collection and storage to in situ resource utilization. This study presents a parametric experimental investigation of regolith discharge dynamics by using the LHS-1 simulant. Results show that vertical vibrations significantly affect the regularity of the flow of granular material through the orifice of the hopper, the average mass flow rate, the spatio-temporal patterning of the material displacement, and the occurrence of jamming (clogging) phenomena. While the average mass flow rate is consistently smaller than that obtained in purely gravitational flow, vibrations induce a significant reduction in the probability of arching and make the overall flow of material much more regular and spatially uniform. Four different flow configurations are identified accordingly in the entire space of parameters, i.e., “funnel,” “mass,” “asymmetric,” and “ratholing” flow. The “funnel” is the most common, while asymmetric and ratholing regimes are only attained for relatively high shaking frequency and amplitude. Low frequencies universally promote arching due to insufficient energy to disrupt force chains within the material. In contrast, the role of high frequencies is more complex, with clogging re-emerging at certain thresholds, particularly at low acceleration amplitude. Increasing the vibration amplitude generally mitigates blockage, but its effectiveness weakens with sample mass growth, indicating that additional factors, such as gravity-induced compaction and related particle rearrangement dynamics also play a significant role in governing such events.