| Internal ocean wave is a common underwater wave phenomenon,which has a significant impact on the development of marine resources and the transportation of matter and energy in the ocean.Through the observation of ocean internal waves,prediction,forecast and early warning can be made in real time according to the propagation speed and time of internal waves,which is of great significance to the safety of internal wave early warning in offshore oil and gas development.In this paper,an ocean internal wave echo observation system is set up,and its influencing factors are simulated and analyzed,and then its observation performance is benchmarked through sea trials.The marine internal wave echo observation system needs long-term and fixed-point observation in the continental slope area of the northern South our country Sea.According to the environmental conditions of the sea area,the technical indicators of the system are determined.In this paper,a small-scale observation carrying equipment buoy is designed for the Acoustic Doppler current profile(ADCP),and its initial stability and natural period are checked and calculated.Then,the shape of the floating body of the buoy is optimized,and the flow field of the buoy with the equipment is analyzed by the fluent software.The analysis results show that the optimized model of the bottom chamfer of the floating body is less affected by the water flow and has better stability;further through the fluid-structure coupling The method of simulating the structural strength of the optimized model is carried out,and the results meet the requirements.The 75 k ADCP has high requirements on the attitude of the buoy on board in seawater.Therefore,the Workbench AQWA software is used to carry out a hydrodynamic analysis of the buoy on board.The anglebetween the buoy and the pitch is relatively small,and the stability is good,which meets the observation requirements of the 75 k ADCP instrument;under the influence of high-frequency waves,the roll and pitch angles of the buoy change greatly.When the period is 3s,the wave roll The angle even exceeds 40°,which may be caused by the resonance of the natural frequency of the buoy model with the wave frequency.In order to make the simulation closer to the real sea environment,the frequency domain motion of a given sea state is simulated by adding irregular wave spectrum and wind spectrum.No meaningful value exceeds 20°,which can ensure that the data observed by the 75 k ADCP instrument is accurate and not invalid.When the wave height is 5m,the roll or pitch angle of the buoy may exceed 20° in some wave directions,resulting in the invalidation of the instrument observation data.Finally,after processing the designed ocean echo observation system,a sea trial experiment was carried out in the northern waters of the South my country Sea.Firstly,the simulation results of carrying buoys are verified by the experimental data,which proves the accuracy of the simulation results of rolling and pitching;Through the benchmark analysis for 8 consecutive days with typical internal wave characteristics,the results show that the echo observation performance is good,and the echo intensity image can clearly see the occurrence of internal waves. |
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