Design And Research Of Synchronous Sampler For Seafloor In Situ Acoustic Measurement

There are two main methods for obtaining acoustic properties of sediments,in-situ measurements and laboratory measurements.In-situ measurement is the direct measurement of sediment by placing the acoustic measuring device on the seabed.The acoustic properties of the sediment obtained by this method preserve the effects of the surrounding environment on the sediment.The data results are more reliable and accurate;Laboratory measurements require early access to sediment samples.Although the resulting sediment acoustic characterization data does not take into account the effects of the in situ environment,But still has a certain reference value,And only through these samples,we can directly obtain the physical and mechanical properties of sediment density,porosity,particle composition,particle size,elastic modulus,etc.These physico-mechanical properties correspond to the acoustic properties of laboratory seafloor sediments.Therefore,in-situ measurement and laboratory measurement have great research on the acoustic properties of sediments,which is indispensable.Current in-situ observation techniques are ubiquitous in that it is impossible to simultaneously achieve stratified measurement and sample collection of sediment samples.There is an urgent need for in situ acoustic observation equipment capable of measuring sediment stratification characteristics while simultaneously achieving sample collection,In order to accurately understand the layered features of seabed sediments and the in-situ acoustic properties of the layers.Based on the urgent need to simultaneously measure the in-situ acoustic properties of sediments and the observation equipment for sediment sample collection,this paper designs a seabed in-situ acoustic measurement synchronous sampling system to establish a bridge between laboratory measurement and in-situ measurement.Based on laboratory measurements,it is possible to correct the reduction to the true state of the seafloor sediment and obtain acoustic properties that are consistent with in situ acoustic measurements.The main research contents of this paper are as follows:(1)A set of seabed in situ acoustic measurement synchronous sampling system was designed.According to the actual working conditions of the system,the general design rules of the system were formulated,and the overall scheme design of the system was completed.The acoustic probe,temperature measuring probe and in-situ measuring head sleeve assembly are designed to solve the problem that the in-situ measuring equipment may be lost during the operation,and the problem of the arrangement of the in-situ measuring equipment cable is solved,which can effectively avoid Cable wire wear and tear(sonic transducers and temperature sensors are placed at the bottom of the system and communicate with the uppermost control unit via cable).The processing and manufacturing of the laboratory simulation prototype of the subsea acoustic measurement synchronous sampling system was completed.(2)The force analysis of the submarine in-situ acoustic measurement synchronous sampler in the underwater falling process and the penetrating sediment process is carried out.(3)Simulation analysis of the working process of the seabed in-situ acoustic measurement synchronous sampling system.The Fluent fluid simulation platform is used to analyze the working conditions of the system in the water stage,and the resistance value and flow field distribution of the system under the impact of the decentralization process,the recovery process and different sea current velocity levels are obtained,and the seawater in the actual operation process is summarized.The adverse effects on the system may be verified,and the designed system can meet the requirements of maintaining a relatively stable state in the water.Based on the Abaqus simulation platform,the finite element simulation analysis of the system sampling process is carried out by using the coupled Euler Lagrangian method.(4)Submarine in-situ acoustic measurement simultaneous sampling system indoor simulation test.The in-situ acoustic measurement synchronous sampling indoor simulation test program was developed,and the indoor simulation prototype of the seabed in-situ acoustic measurement synchronous sampling system was completed,and the seabed environment with three different media of water,muddy sediment and sandy sediment was simulated.The propagation characteristics of the pulse wave in three different media were obtained,and the system sampling process was completed,and the sediment sample was obtained.It was verified that the designed system can simultaneously perform in-situ acoustic measurement and sediment sample collection.Through simulation analysis and experimental analysis,this paper verifies that the subsea in-situ acoustic measurement synchronous sampling system studied in this paper has dual functions of in-situ acoustic measurement and sediment sampling,which can be used in the field of marine monitoring technology,especially related to in-situ acoustic measurement sampling.Device detection system.