Experimental Study On Liquid Sloshing Suppression Of Constrained Floating Plate Under Horizontal Harmonic Excitation

In recent years,agricultural drones have developed rapidly.In addition to agricultural monitoring and crop phenotyping,plant protection drones are more widely used.Plant protection UAV has the characteristics of high operation efficiency,high pesticide utilization rate,low cost,convenient take-off and landing,etc.,which can effectively solve the problem that it is difficult for ground pesticide application machinery in paddy fields,hilly mountains and other areas.In plant protection drones,the quality of chemical solution accounts for about40% of the take-off mass,or even more.At the same time,there are operations such as acceleration,deceleration,turning during the flight of the drone.Due to the presence of acceleration,the liquid in the medicine box is prone to violent shaking.The liquid shaking force acts on the body of the drone,affecting the attitude of the drone,reducing the flight stability,and deteriorating the uniformity of application.In view of this problem,and considering the strict requirements of UAV weight,a device to suppress liquid shaking-elastic restraint floating plate is proposed.Taking the rectangular medicine box commonly used in plant protection UAVs as the research object,the vibration test bench was used to apply horizontal simple and harmonic excitation to the box,and the liquid shaking dynamic measurement device was constructed,and the liquid shaking dynamic data under different liquid depths and different excitation frequencies were measured,and the effects of floating plate area,position and constraint properties on the liquid shaking inhibition ability were analyzed.On the basis of single-layer floating plate,the structure of split floating plate and double-layer floating plate is further proposed,and its liquid shaking inhibition ability is experimentally studied.The test results show that:(1)The liquid sloshing suppression effect of unconstrained floating plates is relatively limited,and the sloshing suppression effect gradually weakens with the increase of liquid depth.After adding an unconstrained floating plate,when the natural frequency is around 0.9f、0.95f、1.0f、and the liquid to liquid ratio is 0.2-0.4,the liquid shaking force is about 75% of the original;When the filling ratio is 0.4-0.6,the liquid shaking force is about 80% of the original.(2)After adding a constrained floating plate,the shaking force near the natural frequency is about 30%-50% of the original,which is closely related to the floating plate area,floating plate position,and constraint stiffness.Overall,the larger the floating plate area,the better the shaking suppression effect;When the position of the floating plate is near the free liquid surface,the shaking suppression effect is better;Elastic constrained floating plates can achieve good sloshing suppression effects over a larger range of liquid depths,while non elastic rope constrained floating plates have stronger liquid sloshing suppression effects in certain situations.(3)When the total area remains unchanged and the constraints are the same,multiple segmented floating plates can also reduce the shaking force,and under certain operating conditions,the liquid shaking suppression effect is even better than the entire floating plate.(4)Compared with single-layer floating plates,double-layer floating plates have less liquid shaking force-the shaking force near the natural frequency is about 70% of that of single-layer plates.Moreover,in a larger range of liquid depths,the double-layer floating plate has good shaking suppression ability.