| Underwater tools powered by seawater hydraulic are a new trend in the future. Because it uses seawater as working fluid it has many advantages such as high reliability, simple system, high efficiency, wide of working depth range, low pollution and can be designed as an open system. As the power unit, the seawater hydraulic motor decides the performance of the underwater tools. With the needs of the underwater operation in deep-sea condition increasing, it is very important to study its characteristics under the deep-sea condition.The effects of different sea depth on the volumetric efficiency and torque characteristics of the motor are investigated with the aid of fluid simulation and numerical simulation during the rotation of the hydraulic motor. Firstly, according to flow characteristics of a single piston chamber mathematical model is built, then utilize MATLAB/Simulink to simulate to get dynamic pressure changes in the piston chamber while hydraulic motor rotating. Secondly, using Fluent and Structural modules, which is on the Workbench platform, analyze fluid-structure interaction of the piston/cylinder interface, then achieving dynamic deformation and leakage while the motor works at different depth. Finally, through the dynamic analysis of the main parts of the motor, obtain thrust reaction face that swash plate exert on the slipper and build driving torque model by combing action of all the thrust reaction of slippers, and friction torque model, then simulate to analyze the impact of different sea pressure level on the torque.Main conclusions: Under the deep-sea condition, both deformation and leakage of piston/cylinder interface will increase, which would lead to lower volumetric efficiency. With the increase of depth, friction torques at start will increase, starting performance turn bad and need a longer time to reach steady state, at the same time the parameters, such as the rotation velocity, the driving torque and the output torque all will decrease. |
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