Research On The Principle And Dynamic Behavior Of Negative-Buoyancy Autorotating-Rotor Underwater Vehicles

Underwater vehicles play an increasingly important role in marine resources exploration and marine environment investigation.The carrying capacity of traditional neutral buoyancy underwater vehicle is limited by space and displacement,so it is difficult to meet the increasing demand of carrying mission sensors.The traditional neutral buoyancy underwater vehicle needs to carry out the structural design and overall balancing again according to the volume,weight and structural characteristics of different sensors,which greatly increases the workload of sensor integration.A new way to solve this problem is to develop a new type of large load underwater vehicle which uses hydrodynamic force to balance the negative buoyancy.This paper presents a new type of negative-buoyancy autorotating-rotor underwater vehicle(NAAUV).Referring to the principle of air autorotating rotor,the NAAUV adopts an autorotating rotor to provide lift and compensate for negative buoyancy,thus achieving effective navigation.Negative-buoyancy vehicles have the advantages of greater carrying capacity,less use of buoyancy materials,smaller size and weight,and lower resistance and energy consumption.The main achievements of this paper are as follows:1.A new concept of negative-buoyancy autorotating-rotor underwater vehicle is proposed.The large-scale double blade rotor is used to generate the lift to balance the negative buoyancy and realize the navigation movement.In the course of navigation,the pitch angle is adjusted to control the size and direction of lift,so as to achieve the control of pitch angle.2.The rotor rotation mechanism is analyzed and calculated by using the blade element theory.On this basis,the rotor scale model is designed and manufactured,and the PIV water tunnel experiment is carried out.Experiments show that the rotor can rotate stably and generate lift under the action of water flow,which proves that the scheme of installing rotor is feasible.In addition,the large-scale rotor used in the underwater vehicle is simulated by CFD,and the expressions of out rotor force and backward force are proposed for dynamic modeling.3.The fluid-structure interaction of rotor with different materials was carried out by using ANSYS.By comparing the important physical parameters such as swing deformation,equivalent stress and stable rotation speed of rotors made of different materials.Due to the small rotating speed of the rotor in passive rotation,the general metal materials can meet the requirements of the advancing blade and the rear blade waving deformation caused by the uneven plane hydrodynamic distribution of the rotor disk.4.A six degree of freedom dynamic model of a negative buoyancy gyroplane underwater vehicle is established.Based on the simplified dynamic model,the dynamic behavior of the underwater vehicle with negative buoyancy rotor is simulated.5.The small-perturbation method is used to derive the longitudinal disturbance equation and the transfer function of the basic motion parameters of the gyroplane underwater vehicle.The results show that NAAUV has good maneuverability and longitudinal stability.