Research On Estimation Of Supercavitation Morphology In Motion Control Of Supercavitating Vehicles

When the vehicle moves in the water with high-speed,the pressure of vehicle's surface will drop to the saturation pressure at the same time,the water will be vaporized to form a bubble.The formation of supercavitation can greatly improve the speed of underwater vehicles,but the formation and collapse of the supercavitation caused the mechanical effects which will have an important impact on the stability of the navigation,the strong nonlinear relationship caused by supercavitation makes the study of cavitation theory difficult.Therefore,the estimation of the supercavitation morphology is a key problem in the motion control of the supercavitation vehicle.In this paper,we will estimate the shape of the supercavity based on the water tunnel experiment of the shrinkage supercavitation model,simulate the motion of underwater vehicle in the actual application environment by controlling the angle of the cavitation and then use STF to estimate the morphology of supercavitation.Finally,verify the correctness of the estimation algorithm in the simulation method and it can satisfy the the need of control of the supercavitation in some practical environment.The main research contents are as follows:Firstly,use the existing theoretical knowledge to establish the mathematical model of the supercavitation vehicle.As the hydrodynamic on the cavitation device and the sliding force generated by the interaction between the tail of vehicle and the edge of supercavitation are both easy to be subjected to external interference and produce strong nonlinear characteristics,and there is no mature solution to the modeling of such conditions,so in this part,we establish a mathematical model of supercavitation vehicle in ideal conditions first,then study the disturbance of the actual noise to the model and improve the model based on the subsequent experimental data.Secondly,complete the related content of the experiment on the water tunnel experimental platform.In this part,we introduce the whole flow of installation and debugging of experimental equipment,including the construction of experimental platform;installation of the supercavitating vehicle model;the structure and function of the servo motor control system;the function of pressurized ventilation equipment;installation and debugging of flow and pressure testing equipment;high speed camera debugging for recording cavitation process and so on.The recorded experimental data are preliminarily processed according to the need for the study of supercavitation.Thirdly,based on the internal,external pressure and morphological data of the supercavitation during the cavitation movement process,and according to the measuring range of the sensor and actual situation,get rid of the abnormal data from all of the measured data,then use STF to estimate the form of supercavitation and improve the mathematical model for supercavitation vehicles.Finally,make a controlling simulation verification in Matlab environment,the results proof: the STF can accurately estimate the morphology of supercavitation in the environment with actual noise interference,as the estimation error is in the allowable range of the supercavitation vehicle controller,so there is no disturbance on the motion stability of the supercavitation vehicle,the estimation algorithm designed in this paper is proven be correct.