一种无缆自动返回式采水器的设计与研究

【作者】 于建清；

【导师】 龚德俊；

【作者基本信息】 中国科学院研究生院（海洋研究所） ， 环境科学， 2008， 博士

【摘要】 海洋环境污染监测、海水化学与地质调查和生物采样,大多数情况下需要现场采集水样。有时需要在不同深度依次采样,获取梯度剖面的现场水体信息,以保证分析结果的统一性、规范性和类比性。近几十年来,水体取样和保存技术迅速发展,各式各样的采水器纷纷问世并获得成功应用。常规CTD葵花式采水器(CTD rosette sampler)(配备尼斯金采样瓶(Niskin bottle)或郭福洛采样瓶(Go-Flo bottle))和船用吸泵均为目前广泛使用的梯度水样采集装置。但其应用各有一定缺陷。因此,设计一种既适用于大型科考船又适用于小型船只、采样深度可精确控制、采水操作简便、无沾污的采水器在海洋科学研究中有较大实用意义。本课题所设计的无缆自动返回式采水器(a New Auto-Returned Column Water Sampling Device-‘ARWAD’)是一种新型垂直剖面采水器,该采水器外挂四个1.5L卡盖式结构的HOUSKIN采水瓶。为采水器加载适当重量的配置体,使其在水中受到负浮力下潜。采水是在释放配置体后,采水器受到正浮力上升的过程中依次完成的。本文的主要内容为:(1)本课题详述了该无缆自动返回式采水器的机械机构与密封方案。采水器的主壳体为硬铝合金圆柱状防水耐压设计,外挂四个卡盖式结构的采水瓶,其机械机构主要包括①配置体的悬挂与释放机构;②采水瓶关闭采水机构;(2)详述该采水器的控制系统,包括硬件设计方案和软件设计,并对控制系统进行了调试。控制系统装置于主体的防水耐压仓内,以单片机为核心,装载压力传感器获知水深。下位机程序控制在到达指定深度时释放配置体和关闭各采样瓶,上位机程序实现在甲板上的自检、设定配置体的释放深度和各采水瓶的关闭采样深度;(3)用解析法和经验公式对该采水器承压零件尺寸进行设计,同时用数值计算方法对其强度校核;(4)为保证采水器的采水精度和确保其工作安全,对采水器进行水动力学计算,确定阻力及阻力系数等参数,使采水器在上升采水过程中最大速度小于2.0m/s,以为外形设计提供参考;(5)采水器采样性能验证。现场采集水样后,在实验室测定悬浮颗粒物的质量浓度和体积浓度分布。在采集水样的同时,应用激光粒度仪获取现场悬浮物粒径分布信息。通过与激光粒度仪现场测定结果对比,证明该自动返回式采水器采水深度准确,质量较好。该采水器使用时无需钢丝绳,而是装载压力传感器获知水深,由此避免了使用绞车和由钢丝绳计量深度带来的深度误差;采样时也无须连接电缆,节省电力;自由下潜和上升,无需配备绞车深度补偿设施,避免出现深度逆变现象。主要应用于驾驶小规模船只在较浅水域(湖泊或河口)采水,亦可用于大型科考船,其结构轻便、造价低廉以及操作方便等性能使其成为CTD葵花式采水器和泵采系统的有益补充。更多还原

【Abstract】 Capable of collecting water samples from chosen locations and discrete depths is essential for charactering the vertical and horizontal distribution of the physicochemical and biological elements of most types of water column. Sampling could be defined as a process of selecting a portion of material small enough in volume in selected location to be transported conveniently, handled and latterly analyzed in the laboratory. In some circumstances, it is demanded to sample in columned water at distinct depths to obtain vertical distribution information. Various qualified devices or samplers have been developed and come into wide use in recent decades.In most circumstances, either a conventional CTD rosette sampler equipped with Niskin (or Go-Flo) bottles or a shipboard pumping system whch are employed for accurate water sampling still have disadvantages in the application. It is essential to design a new kind of sampling device which is suitable for different size of ships.I describe here a new type of Auto-Returned WAter sampling Device (ARWAD) which is designed primarily for collection of column water in shallow systems (gulf, lakes or estuaries), with operations conducted even from a small boat. Pre-set each bottle’s sampling depth on the deck, the ARWAD is launched carrying 4 or more 1.5-liter Niskin bottles. Attached with adjustable weight, ARWAD falls deep in the water under its own gravity with no oceanographic wire attached to. Trapping each bottle water sample at determined depth is done during the retrieve process, after casting away the weight attachment.(1) The mechanical design and the seal method are presented in the paper. The mechanical system for ARWAD consists of①weight attachment loading and unloading system, and②bottle firing mechanical system.(2) The control system for the ARWAD is designed based on the utilization of a single-chip microcomputer SST89C54. The hardware circuit and software method design are presented. The ARWAD interfaces with high performance pressure transmitter to provide accurate sampling capability, depending on user requirements. The MCU program is to control the weight attachment loading and unloading process and bottle firing system; the PC program is to pre-set weight attachment unloading depth and each bottle firing depth.(3) Mechanical components are designed, and their mechanical strength is verified both in analytic method and FEM (Finite Element Method).(4) For controlling its rising speed of the ARWAD (with no more than 2.0m/s) to make sure the depth accuracy, FEM method is utilized to calculate the sampler’s resistance coefficient and its maximum rising speed.(5) The ARWAD sampling device has been tested in natural body (in Jiaozhou Bay) in April, 2008 by collecting column samples for suspended solids materials analysis later in laboratory. For comparison purposes, a LISST was used to obtain vertical profiler data of particle size distribution (PSD) at the same site after the ARWAD sampling is done. The sample results (ARWAD laboratory measurements) and LISST data have good correlation, which means ARWAD works quite well.There is no hydrowire attached to the ARWAD, so the depth recording error brought by vane and hydrowire is eliminated to minimal. A present commonly used CTD rosette is often fixed to the end of an electromechanical cable, and the water sampling bottles are closed when desired by electrical command from on deck. Unlike a CTD rosette, the ARWAD is free to fall vertically, which eliminates the need for motion compensated winch systems and performs its duty to trap column water by command directly from control system in the pressure case. Larger volumes of water may be obtained by using larger water sample bottles. ARWAD could be used as a complement of traditional CTD sampler or pump with its benefits including small size, low cost to construct and operation, and ease of deployment in a small boat.更多还原