Design And Experimental Study Of Integral Airtight Sampler For Deep Sea Sediment

The abyss contains a large number of microbial communities and sediments.They are important media for human to understand and research on the evolution of abyss and the changes in the abyss.In order to meet the demand of abyss seabed scientific research for high-quality abyss sediment samples,it is not only urgent but also significant to develop a gas sampling device for abyss seabed sediments with pressure holding function.In this paper,according to the requirements of the abyss seabed sediment pressure holding sampling technology and the working ability and maneuverability of the whole sea deep manned submersible manipulator?hereinafter referred to as airtight sampler?,a sea-deep sediment gas-tight sampler with pressure maintaining function was designed and related research was carried out.The main research work of the thesis is:Firstly,the current research status of deep-sea sediment samplers at home and abroad is analyzed,and the main problem of sampler pressures from 30MPa to 70MPa at home and abroad are discussed.The pressure-maintenance function of 110MPa deep sea environment developed in this paper is clarified.The technical requirements of the airtight sampler are comparatively analyzed.The characteristics of the two design schemes of the hydraulic drive and the mechanical drive sampler are compared and the latter is determined as the design of the paper.According to the physical and mechanical properties of the sediment,the force of the sampler when sampling on the seabed is carried out.After analysis,the diameter of the sampling tube,the strength limit of the sample under compression and the friction coefficient between the inner wall of the sample tube and the sample were obtained as the main factors affecting the sampling rate of the airtight sampler.Combined with the test verification,the important parameters such as the reasonable inner diameter of the sampling tube D₁=40mm and the length of the sampling tube L=560mm were determined.Secondly,according to the overall design scheme,the overall structure and key component design criteria of the airtight sampler are determined,and some key components such as sampling tube,pressure holding cylinder,sealing cylinder and spring support assembly are calculated and analyzed;The recovery spring was tested.The test results show that the sampling tube can be fully retracted into the pressure-retaining barrel under the recovery spring,which verifies the feasibility of the designed spring.The seawater to be compensated by the pressure-retaining cylinder is studied.The relationship between the volume,the effective volume and the pressure difference between the internal and external pressure cylinders is proposed.The design criteria of the pressure compensator are proposed,and the system active pressure compensation scheme is formed.Then,using the finite element tool,the relationship between the different structural parameters of the key components such as the pressure cylinder and the flap seal valve and the quality of the airtight sampler and the bearing pressure are analyzed,and the corresponding optimization design criteria are obtained.The Behnken test design and response surface establishes the mathematical model of the airtight sampler structure,and analyzes the response surface of the pressure-retaining cylinder and the flap sealing valve respectively.The response surface analysis results show that the inner diameter and wall thickness of the pressure-holding cylinder are the same.The maximum stress effect is most significant.The eccentric angle of the flap seal valve has the most significant influence on its mass and maximum stress.The fitted regression model can well reflect the maximum stress and weight of the key components of the airtight sampler and the structural parameters.relationship.Finally,the structural components of the sample components such as sampling tube,support fixture,flap seal valve,spring support assembly and manual pressure pump and the integrated assembly scheme of the airtight sampler system are introduced,and the airtight sampler test based on the research group is introduced.The prototype was tested by internal and external pressure.The test verified the reliability of the pressure-tight performance of the airtight sampler,the system principle and the rationality of the structural design,and provided theoretical basis and technical support for the design and manufacture of the full sea depth sampling device.