Debris flows form deposits when they reach an alluvial fan until they eventually stop.However,houses located in the alluvial fan might affect the debris flow flooding and deposition processes.Few previous studies have...Debris flows form deposits when they reach an alluvial fan until they eventually stop.However,houses located in the alluvial fan might affect the debris flow flooding and deposition processes.Few previous studies have considered the effects of houses on debris flow flooding and deposition.This study conducted model experiments and numerical simulations using the Kanako2D debris flow simulator to determine the influence of houses on debris flow flooding and deposition.The model experiments showed that when houses are present,the debris flow spreads widely in the cross direction immediately upstream of the houses,especially when the flow discharge is large or the grain size is small.Houses located in the alluvial fan also influence the deposition area.The presence of houses led to flooding and deposition damage in some places and reduced the damage in others.The simulation also demonstrated the influence of houses.Both the model experiment and the simulation showed that houses change the flooding and deposition areas.展开更多
Motivated by optimal combination of paired wings configuration and troke-plane inclination in biological flapping flights that can achieve high aerodynamic performance,we propose a biomimetic rotor-configuration desig...Motivated by optimal combination of paired wings configuration and troke-plane inclination in biological flapping flights that can achieve high aerodynamic performance,we propose a biomimetic rotor-configuration design to explore optimal aerodynamic performance in multirotor drones.While aerodynamic interactions among propellers in multirotor Unmanned Aerial Vehicles(UAVs)play a crucial role in lift force production and Figure of Merit(FM)efficiency,the rotor-configuration effect remains poorly understood.Here we address a Computational Fluid Dynamics(CFD)-based study on optimal aerodynamic performance of the rotor-configuration in hovering quadrotor drones with a specific focus on the aerodynamic effects of tip distance,height difference and tilt angle of propellers.Our results indicate that the tip distance-induced interactions can most alter lift force production and hence lead to remarked improvement in FM,and the height difference also plays a key role in improving aerodynamic performance,while the tilt angle effect is less important.Furthermore,we carried out an extensive analysis to explore the optimal aerodynamic performance of the rotor-configuration over a broad parameter space,by combining the CFD-based simulations and a novel surrogate model.We find that a rotor-configuration with a large tip distance and some height difference with zero tilt angle is capable of optimizing both lift force production and FM,which could offer a novel optimal design as well as maneuver strategy for multirotor UAVs.展开更多
基金supported by JSPS KAKENHI(Grant No.24710206),Grant-in-Aid for Young Scientists (B)
文摘Debris flows form deposits when they reach an alluvial fan until they eventually stop.However,houses located in the alluvial fan might affect the debris flow flooding and deposition processes.Few previous studies have considered the effects of houses on debris flow flooding and deposition.This study conducted model experiments and numerical simulations using the Kanako2D debris flow simulator to determine the influence of houses on debris flow flooding and deposition.The model experiments showed that when houses are present,the debris flow spreads widely in the cross direction immediately upstream of the houses,especially when the flow discharge is large or the grain size is small.Houses located in the alluvial fan also influence the deposition area.The presence of houses led to flooding and deposition damage in some places and reduced the damage in others.The simulation also demonstrated the influence of houses.Both the model experiment and the simulation showed that houses change the flooding and deposition areas.
基金This work was partly supported by the Grant-in-Aid for Scientific Research of KAKENHI No.19H02060,19H00750,JSPSa Global Prominent Research Program,Chiba University.
文摘Motivated by optimal combination of paired wings configuration and troke-plane inclination in biological flapping flights that can achieve high aerodynamic performance,we propose a biomimetic rotor-configuration design to explore optimal aerodynamic performance in multirotor drones.While aerodynamic interactions among propellers in multirotor Unmanned Aerial Vehicles(UAVs)play a crucial role in lift force production and Figure of Merit(FM)efficiency,the rotor-configuration effect remains poorly understood.Here we address a Computational Fluid Dynamics(CFD)-based study on optimal aerodynamic performance of the rotor-configuration in hovering quadrotor drones with a specific focus on the aerodynamic effects of tip distance,height difference and tilt angle of propellers.Our results indicate that the tip distance-induced interactions can most alter lift force production and hence lead to remarked improvement in FM,and the height difference also plays a key role in improving aerodynamic performance,while the tilt angle effect is less important.Furthermore,we carried out an extensive analysis to explore the optimal aerodynamic performance of the rotor-configuration over a broad parameter space,by combining the CFD-based simulations and a novel surrogate model.We find that a rotor-configuration with a large tip distance and some height difference with zero tilt angle is capable of optimizing both lift force production and FM,which could offer a novel optimal design as well as maneuver strategy for multirotor UAVs.
