Study On The Ocean Microstructure Turbulence Measurement Technology Based On Underwater Glider

Sea is the largest ecological system on the earth;there are innumerable motions of different scales and varied sizes in it.Most of the energy is diffused from large-scale motion to micro-scale motion,finally dissipated in the way of turbulent mixing.Oceanic turbulence accelerates the diffusion of dissolved matter and particulate matter,thus exerting great impact on the temperature and salinity.Meanwhile,oceanic turbulence has a close connection with some scientific fields such as aerology,acoustics and sedimentology.Therefore,the study on oceanic turbulence is of significance to get a better understanding of oceanic operation mechanism and other related oceanic fields.In recent years,oceanic turbulence attracts more attention from oceanic scientists.The process of oceanic study is slow due to the limited technology of turbulence observation.As a new type of underwater-unmanned vehicle,underwater glider has the features of low energy consumption,long working time,deep submarine navigation and so on.Serving as turbulence observation instrument,it can realize the function of oceanic turbulence observation with the advantages of continuity,wide range and long time.Aiming at the study on the ocean microstructure turbulence measurement technology based on underwater glider,the work we have done as follows.First,the mounting positions for MicroRider is designed by combining the working principle of MicroRider with the motion features of glider,and the influence on turbulence data with different mounting position for MicroRider are analyzed with CFD simulation,and then the optimal position is obtained.Second,analyzing the relation among gliding velocity,attack angle and pitching angle in the vertical plane by establishing the dynamic model of turbulence observation glider.Third,with the consideration of the impact on turbulence data from external vibration,the advantage and disadvantage of Fourier Transformation and Wavelet signal processing methods are illustrated,and aiming at the shortages of Fourier Transformation and Wavelet,the Matching Pursuit based on Wavelet is proposed,improving the observation accuracy of turbulence data.Finally,the dynamic model of underwater glider and turbulence data processing methods are verified by the sea trial.The major research result and innovations:I.Considering the working principle of MicroRider,the influence on turbulence data with different positions of MicroRider is analyzed by the method of CFD.And the relation among velocity,attack angle and pitching angle is analyzed by the kinematics equations in vertical plane,the optimal velocity and attack angle for turbulence observation are obtained by the sea trial.II.Aiming at the shortages of Fourier Transformation and Wavelet,the Matching Pursuit based on Wavelet is proposed.The method is proved by processing the simulation signal and real signal,which makes up the lacks for former two.III.Turbulence distribution situation of 19 profiles in the neighborhood of Kuroshio is acquired,based on underwater glider,providing abundant data for oceanic scientists to further study Kuroshio.