自同步式冰下沉积物振动取样器设计与实验研究

发布时间：2018-07-12 15:53

本文选题：自同步振动机理 + 南极冰下环境　；参考：《吉林大学》2017年博士论文

【摘要】：南极冰架下、冰下湖水体底部沉积物包含着重要的古气候、古环境信息,可为研究南极冰架的进退历史、冰架下海洋环流方式提供历史尺度的观测手段,同时也为极地环境下微生物生命形态的研究、原始生命形式的探索带来新的契机。目前,南极冰下沉积物样品的获取主要依托于热水钻技术,取样设备需要通过热水钻先导孔到达水体底层后,才能开展沉积物的取样操作,特殊的工作场合对取样器的选型、设计提出了一系列的技术挑战。本文对南极冰下沉积物取样技术特点进行分析,总结该领域存在的若干技术难题,综合常规水下沉积物取样器、南极冰下沉积物取样器的研究现状,提出自同步式冰下沉积物振动取样器的设计方案。论文主要取得了以下研究成果:1、参照我国“863”项目“冰架热水钻机关键技术与系统开发”中的相关参数要求,完成了取样器的整体结构设计。整体结构采用模块化的设计方法,将取样器拆解成防水压力舱、振动器、取样管部件以及弹簧减振器四个主要部件,按照相关逻辑顺序对各部件逐个展开设计。其中,在振动器部件的设计中,引入双质体振动系统自同步原理,设计了双电机自同步式柱状振动器,使取样器的径向结构尺寸大大缩小。最终确定取样器的结构设计参数为:最大径向尺寸270mm,整体长度4.3m,总质量203kg,取芯长度3m,取芯直径94mm,总功率400W,。2.基于ANSYS Workbench模拟分析平台,模拟压力舱部件在2200m水体内振动状态下的承载状态,分别建立压力舱部件的结构静力学、瞬态动力学有限元分析模型,观察模型在静载、静-动载荷条件下的力学响应。在结构静力分析模块中对压力舱模型施加静态水压载荷,得出结构承载条件下的受力危险区域,并结合分析结果对原始结构进行改进设计。在结构瞬态分析模块中对改进后压力舱模型同时加载水压载荷、振动载荷,分别分析了压力舱结构在水压-纵向振动、水压-水平振动两种载荷作用下的力学响应,最终验证了本文所设计的压力舱结构在水压、振动载荷联合作用下耐压性能。3.建立了冰下沉积物取样模拟测试实验台,对取样器的同步性能及取样能力进行了测试。实验结果表明:(1)取样器在悬停、进尺过程中均能快速达到同步振动状态,振动频率0-46.5Hz无级可调,加速度幅值为1.33g;(2)在使用模拟沉积物的物质组成与南极冰下沉积物相近的情况下,所设计取样器能够达到指定的3m进尺深度,并且所取沉积物样品压实率较低、水-沉积物交界面保存良好;(3)与依靠取样器自身惯性的重力式贯入取样相比,振动式取样的贯入深度为重力式取样的两倍以上。4.所设计振动取样器能够实现竖直、水平、竖直-水平交替三种振动模式,利用模拟测试实验台,对三种模式下的进尺速率进行对比性实验。实验结果表明:振动模式的变更会对取样器的进尺速率造成一定的影响。三种振动模式中,交替振动模式下取样器的平均进尺速率最高,可达到77.8mm/s;水平、竖直振动模式下的平均进尺速率依次递减,分别为71.17mm/s、54.9mm/s;三种模式下,取样器均能够在80s内完成3m以上的进尺深度。此外,取样管进入沉积物后,适当的对振动模式进行变换,有助于提高取样器的贯入能力。目前,我国正在加大投入南极热水钻系统的研究,中国南极热水钻探项目计划明年在南极埃默里冰架实施热水钻探目标。本文所提出的自同步式冰下沉积物振动取样器,针对“863”项目“冰架热水钻机关键技术与系统开发”进行设计。通过有限元模拟分析及实验测试,初步验证了取样器结构设计、工作原理的可行性,为我国南极冰下沉积物取样设备的研制提供了重要的技术支持。
[Abstract]:Under the Antarctic ice shelf, the bottom sediments of the subglacial lake water body contain important paleoclimate. The Paleoenvironment information can provide historical scale observation means for the study of the Antarctic ice shelf history, the ocean circulation under the ice shelf, and the research on the microbial life form under the polar environment. The exploration of the primitive life forms brings a new opportunity. Before, the acquisition of the subglacial sediments in Antarctica is mainly based on the hot water drilling technology. The sampling equipment needs to carry out the sampling operation of the sediment by the hot water drilling pilot hole to the bottom of the water body. A series of technical challenges are put forward for the selection of the sampler in special work situations. This paper takes the sampling technique of the subglacial sediments in the Antarctic. The characteristics are analyzed, and some technical problems in this field are summarized. The research status of the conventional underwater sediment sampler and the Antarctic subice sediment sampler are summarized. The design scheme of the self synchronous underwater sediment vibration sampler is proposed. The main results are as follows: 1, referring to the "863" project "ice shelf hot water rig" in China The integral structure design of the sampler is completed by the relevant parameters in the key technology and system development. The overall structure uses a modular design method to dismantle the sampler into a waterproof pressure chamber, vibrators, sampling tube parts and spring damper four main components, which are designed one by one according to the logical sequence. In the design of the vibrator components, the self synchronizing principle of dual mass vibration system is introduced, and a dual motor self synchronous cylindrical vibrator is designed to make the radial structure size of the sampler greatly reduced. Finally, the structure design parameters of the sampler are determined as the maximum radial size 270mm, the length of the whole body 4.3m, the total mass 203kg, the core length 3M, the core diameter. 94mm, total power 400W,.2. based on the ANSYS Workbench simulation analysis platform, simulate the bearing state of the pressure chamber components in the vibration state of the 2200m water body, establish the structural statics of the pressure compartment components, the transient dynamic finite element analysis model, observe the mechanical response of the model under static load, static and dynamic load conditions. In the block, the static water pressure load is applied to the model of the pressure chamber, and the dangerous area under the condition of structure loading is obtained, and the original structure is improved with the result of the analysis. In the structure transient analysis module, the water pressure load and the vibration load are loaded at the same time, and the hydraulic pressure longitudinal vibration of the pressure tank structure is analyzed. The mechanical response of the two kinds of loads under the action of two kinds of loads, such as motion, water pressure and horizontal vibration, finally proved that the pressure cabin structure under the combined action of water pressure and vibration load designed in this paper has set up an underwater sediment sampling simulation test bench to test the synchronizing performance and sampling ability of the sampler. The experimental results show that: (1) sampling (two) In the process of hovering, the synchronous vibration state can be achieved quickly, the vibration frequency 0-46.5Hz is stepless and the amplitude of the acceleration is 1.33g; (2) the designed sampler can reach the specified 3M depth and the compactness of the sediment sample under the condition that the material composition of the simulated sediments is similar to the Antarctic subglacial sediments. Lower, the water sediment interface is well preserved; (3) compared with the gravity penetration sampling which depends on the self inertia of the sampler, the vibratory sampling depth is two times more than the gravity sampling.4., and the vibration sampler can achieve the vertical, horizontal, vertical and horizontal alternation of three vibration modes, and use the simulated test bench for three kinds. The experimental results show that the change of the vibration mode will have a certain effect on the footage rate of the sampler. In the three vibration modes, the average footage rate of the sampler under the mode of alternating vibration is the highest, which can reach 77.8mm/s; the average footage rate in the vertical vibration mode decreases in turn, In the three modes, 71.17mm/s, 54.9mm/s, the sampler can complete the depth of more than 3m in the 80s. In addition, after the sampling tube enters the sediment, the proper transformation of the vibration mode is helpful to improve the penetration ability of the sampler. At present, China is increasing the research on the Antarctic hot water drilling system, China's Antarctic hot water drilling. The project plans to implement the hot water drilling target in the Antarctic Amery ice shelf next year. The self synchronous underwater sediment vibration sampler proposed in this paper is designed for the "863" project "key technology and system development of ice shelf hot water drill". Through the finite element simulation analysis and experimental test, the structure design of the sampler is preliminarily verified. The feasibility of the principle provides important technical support for the development of the sampling equipment for the Antarctic subglacial sediments in China.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P343.6;P634.3

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