Design And Experiments Of Shear Sensor And The Profiler For Ocean Microstructure Measurement

Turbulence is responsible for dissipating the kinetic energy in the Ocean at very small scales, and it is essential to set up ocean model that predict global circulation, climate change, and particle dispersal. Microscale turbulent mixing below the sea surface strongly influences the heat, mass and momentum exchange between the ocean and the atmosphere. Water velocity, heat, salinity, and nutrients are primarily dependent upon turbulence. So turbulence has significance to research the motion regularity of the ocean.In order to descirbe turbulence in the ocean, the magnitude of the turbulent velocity fluctuations and the rate of dissipation of turbulent kinetic energy should be measured or estimated. The most commonly used and best-suited sensor for measuring microstructure velocity fluctuations is the shear sensor. The sensing element is a piezo-ceramic bimorph beam which generates an electrical charge in response to cross-axial forces. The sensor is installed on the top of the profiler, and move with it. Profiler can be categorized as either vertical or horizontal profiler. Based on the signal and sensitivity of shear sensor, ocean viscosity and velocity of the profiler, dissipation of the turbulence can be computed.At present, there are little research on structure design, mechanical properties, and water dynamics of shear sensor and profiler. But such factors are critical to the measurement accuracy of the instruments. In addition,nearly all the ocean turbulence measurement instruments are imported in our country, with the further development on ocean science, more precise measurement instruments need be explored. Supported by national high technology of ocean monitor field, this paper presents a thorough study on the structure of shear probe and dynamics property of vertical profiler. New shear sensors and experiment instruments are explored, and technologies are passed the acceptance and put into practice.The main contributions of this thesis are summarized as follows:1. New shear sensor made of PVDF is developed. Based on the structure and work environment of shear sensor, fluid solid interaction coupling and piezoelectric coupling are introduced to compute the property of shear sensor. The result is coMPared with experiment, which suggests the method is feasible.2. The calibration machine system and dynamic test instrument are develped in order to acquire the sensitivity and test the property of the shear sensor.3. The hydrodynamic property of vertical profiler is studied by Computational Fluid Dynamics (CFD). The kinematics and dynamics equation are deduced, trajectory path and velocity of profiler are simulated.