温室卷帘机构设计含11张CAD图带开题
温室卷帘机构设计含11张CAD图带开题,温室,卷帘,机构,设计,11,十一,cad,开题
开题报告题目温室卷帘机构设计学生姓名、学号专业指导教师姓名职称一 研究的背景、意义 温室的自然通风设备是一个极其复杂的过程,这一过程取决于温室的所有参数(额定值,位置和窗户的几何形状以及漏孔面积等等)和外部环境条件。这种现象持续不断的利害关系会导致自然通风设备在质量和能量上的不平衡,并进一步严重影响室内环境。 自从1954年Morris和Neale 第一次对温室开窗设备中的自然通风设备进行实验性研究以来,人们越来越多地考虑到潜在的物理现象对通风设备影响。几十年后,Baiely和Cotton以及Miguel以及其他的实验论证了在植物和温室顶棚之间使用遮阳网的潜在好处。近期以来,在开窗设备5处采用幕帘下是为了防止昆虫进入,这样即可减少用化学杀虫剂。所以,幕帘表面的气流研究同样是一门重要的课题。现有的对这个课题的分析方法大致可以分为以下两种:(1):经验主义和半经验主义的研究方法研究穿过和幕帘的气流。(2):以流体机械公式为指导数字化的解决问题。 属于第一种类型的所有模式基于的理论思想是在气流与驱动气流循环运动的潜在物之间有一种简单的非线性关系。这种分析认为温室室内的空气是不可压缩的,这一分析纯碎根据经验或贝努利方程所得。尽管简单的假设是与具体实验下得到的改正系数结合在一起的,还是大大限制了这项研究成果的有效范围。 第二种模式中,采用一种数字化模拟程序来解决惯性方程,动能和能量方程,决定速度,温度及压力和温室内最终气流循环模式。世界各国的现代温室,于20世纪60年代逐步完善并快速发展。第二次世界大战后,各国都致力于自身的经济发展。因此,经济迅速恢复和快速发展,人们的生活质量大幅度提高,对农产品提出了更高的要求;随着科学技术的进步和工业水平的提高,也加快了农业的工业化进程,设施农业应运而生,在全球迅速崛起,并形成资金、技术劳动力密集型的高新技术产业,也是当今世界最具活力的产业之一,现代温室也随之快速发展。从国内外现代设施园艺发展情况来看,特别是发达国家,现代温室大多以大型连栋温室为主,其中塑料薄膜温室约60万公顷(含中国的日光温室及塑料大棚),主要分布在亚洲;玻璃温室约4万公顷,主要分布在欧洲;新型覆盖材料聚碳酸酯板温室近几年来有较快发展,目前约有1万公顷,零星分布于世界各国。 荷兰是世界上温室产生最发达的国家,其温室以大型玻璃温室为主体,现有大型连栋玻璃温室面积1.0*104hm2,约占世界玻璃温室的1/4,居世界之首。其中花卉栽培面积为5000hm2,蔬菜栽培面积为5000hm2。荷兰温室生产水平很高,如番茄的生产,20世纪80年代初以来其产量提高很快,每平方米番茄年产量1970年为20kg左右,80年代后期超过40kg,现在达到50-60kg。其主要原因是:无土栽培的普及,高产品种的开发,增加温室高度而改善了栽培环境,计算机应用的普及,施肥和环境管理的改善,利用昆虫授粉和利用昆虫天敌治理虫害等。荷兰全国每年花卉出口收入达15亿美元。蔬菜出口收入达10亿美元。其全自动化温室成套设备在世界上享有很高的声誉. 我国现有现代化的大型连栋温室大棚面积近200hm2,其中,由我国自行设计和建造的有50hm2,自荷兰、美国、以色列、日本、韩国、法国、西班牙等11个国家和地区引进的现代化温室140hm2以上,其中大型连栋充气大棚约占2/3,玻璃温室占1/3。大型现代化温室及大棚南方多用于花卉栽培,而北方以蔬菜为主,部分用于栽培苗木。 引进国外的玻璃温室骨架多采用双层面式钢骨架,而塑料薄膜连栋充气温室,采用圆弧拱顶结构,有的可将部分拱顶开作天窗。除日本的连栋大棚高度为3.5 m较矮以外,其他国家的连栋温室、大棚一般高达5-6.5m,结构高大;因温室、大棚要常年处在高温高湿条件下,对骨架材料不仅要求强度高,而且要耐蚀性好,要热镀锌或进行防绣处理,温室大棚的立柱及拱架粗度为50-75mm间,壁厚达3mm以上。引进的温室其连栋大棚的结构也有所不同。我国温室发展迅猛,但由于冬季温度低,日照时间短,成为发展温室的两大自然障碍。日光温室在寒冷的冬季必须在透明物上覆盖保温材料,从而解决温度低,日照时间短的问题。卷帘机构就成为温室发展不可或缺的设备。卷帘是温室的通风换气和温度调节装置之一。温室的迅猛发展对之配套的卷帘装置提出了新的要求。以往卷帘虽要人工干预手动控制,能实现任意开度控制,但其低效率和高劳动强度严重影响作业质量。现在的卷帘机构可由计算机自动控制,能实现开启或关闭两种状态。结合两种控制的优点,计算机控制并可实现任意开度的卷帘装置成为今后的发展趋势。国内外现有的卷帘机构大体可分为手摇式和电动式。由于经济,技术等条件的制约,手动卷帘机构和机动卷帘机构在国内的温室栽培中都受到广泛运用。卷帘机构主要分为:(一).手摇卷帘机:最初的卷帘设备是人工的,称为手摇卷帘机。人力卷帘机以缠绕式为主。 主要是根据保温被的巻铺原理,在保温被的下端横向固定一根铁管作为卷帘轴, 在轴的两端安装卷帘机构。通过摇转绕线轮,钢索牵引卷帘轮转动,即可实现卷帘; (二).电动卷帘机:电动卷帘机的种类很多,根据传动方式的不同就可分为V带传动,齿轮传动,滑轮移动等卷帘机。从工作原理区别,电动卷帘机可分为以下几种: 1.单轴牵引型卷帘机:该机由卷帘机组、牵引轴、轴承座、轴承支架、牵引绳、卷帘杆等构成。卷帘机组固定安装在温室顶部的一端,包括三相电动机与蜗轮传动减速器。减速器的输出轴为单头,与牵引轴相联。牵引轴沿温室纵长方向通过轴承座、轴承支架固定在温室顶部。牵引绳呈对折状,其1/2长度铺压在草帘之下,此段的绳头拴系在温室顶端,另1/2长度位于草帘之上,其绳头按一致的旋向缠绕在牵引轴上,并通过绳卡将绳头固定在牵引轴上。草帘的上端被固定在温室顶部,下端与卷帘杆固定在一起。按动卷帘机控制开关的按钮,令卷帘机组驱动牵引轴转动,随着牵引绳在牵引轴上被缠绕的圈数增多,牵引绳对折于草帘上、下方的长度不断缩短,草帘即被平稳地沿棚面向上拉动卷起。反之,令卷帘机组驱动牵引轴反向转动,使牵引绳在牵引轴上缠绕的回数减少,牵引绳对折于草帘上、下方的绳长增加,在被卷草帘自重的作用下,草帘逐渐沿棚面向下展开,直至完全将温室棚面覆盖。由于减速器为单头蜗杆减速器,其输出轴具有自锁功能,因此牵引轴可在任意转动位置锁止,被卷动的草帘亦可在揭启的任意位置上停滞静止。为防止因偶然停电而影响保温帘的正常揭启、覆盖作业,同时兼顾某些地方使用三相电源不便,减速器的输入轴设为双头,除一头与电机相联外,另一头可联结手轮。在停电或无电源的情况下,通过转动手轮操纵卷帘机组运转,即可使保温帘得以揭、盖。手轮以辅助劳力即可轻松摇动,以此操纵整栋温室。单轴驱动的牵引型卷帘机主要适于长度为60米以内的单坡面温室应用。2.双轴牵引型卷帘机:该机的机构和工作原理与单轴驱动牵引型卷帘机相似,不同点在于:其蜗轮减速器的输出轴为双头,使用时固定安装在温室顶部的中央(图2.3),两输出轴分别与两边的牵引轴联接,并驱动其对牵引绳进行牵引或放松动作。这种双轴驱动牵引型卷帘机适合长度为120米以内的单坡面温室应用。 以上两种形式卷帘机构简单、造价低廉、工作性能可靠。但是,由于其卷帘机组、牵引轴等主要工作部件须安装固定于温室顶部,因而对温室顶部建筑结构极其强度有一定要求,同时对安装的技术也相对较高。3.自驱动型卷帘机:该机由卷帘机组、卷帘杆、压铁、伸缩支杆和铰接支座等构成(图2.4)。卷帘机组固定在伸缩支杆上端的机座上,减速器的输出轴通过法兰盘与横贯温室全长的卷帘杆相联,卷帘杆全长上均匀地设有螺孔。保温帘的上端固定在温室顶部,下端通过螺栓与压铁被压紧在卷帘杆上。按动卷帘机控制开关的按钮,卷帘组即直接驱动卷帘杆转动。当驱动卷帘杆沿棚面向上方转动时,卷帘杆即带动保温帘边自卷边向上滚动,由于支撑卷帘机组的伸缩支杆的长度可随卷帘机组位置变动而自由变化,因此卷帘机组亦随之上升,从而使保温帘揭启。反之,令卷帘机驱动卷帘杆反向转动时,保温帘则在自重作用下沿棚面向下方滚动,使其重新恢复到覆盖状态。 与牵引型卷帘机相比,这种自驱动型卷帘机的构造更为简单。特别是它无须在温室顶部安装任何附属构件,因而不仅对温室顶部的建筑结构与强度无特别要求,而且安装施工亦非常方便、快捷。但是,自驱动型卷帘机要求减速器的传动比较大,一般为1:300左右,减速器设计一般为二级传动,故成本略高。4.双向牵引型卷帘机:对于棚面坡度平缓(小于10度)的温室,当需要保温帘由卷起状态向下翻滚,展开到覆盖状态时,仅依靠保温帘的自重是难以实现的。另外,对于具有后坡,并且后坡亦以保温帘覆盖的温室,欲将保温帘从后坡底部由卷起状态向上翻滚展开时,不借助外力更是不可能的。因此,这些情况下须采用双向牵引型卷帘机,即保温帘由卷起状态向覆盖态翻滚展开时,也利用动力和牵引绳作反向拉动。双向牵引型卷帘机与其它形式卷帘机的区别在于,它在温室的前沿多设置若干组滑轮和反拉牵引绳等构件。反拉牵引绳的一端拴系于保温帘最下部,另一头按正拉牵引绳相反的旋向缠绕固定在牵引轴上。当保温帘卷起时,反拉牵引绳在牵引轴上缠绕的圈数随牵引轴转动而减少。其下端则随保温帘卷动而卷夹在保温帘各层之间,并向上卷动。当虽要保温帘翻滚展开时,则驱动减速器反转,使正拉牵引绳在牵引轴上的缠绕圈数逐圈减少,而反拉牵引绳在牵引轴上缠绕圈增多,反拉牵引绳即通过滑轮而拉动保温帘反向翻滚,从而实现展开。二 课题研究的基本内容、重点难点及要解决的主要问题2.1基本内容 大体思路是设计一种启动装置能与卷轴同步升降的自驱动卷帘机。卷轴从下往上卷动,因为缠绕在卷轴上的透明幕帘(多用薄膜)的上端粘结在温室侧墙顶端,承受了作用力,卷轴就不会明显弯曲(少许的弯曲是在误差范围内的)。同步升降卷帘机主要包括:启动装置(电动机),传动装置(减速器,联轴器传动),执行装置(卷轴)以及同步升降配套装置(固定导轨,钢丝等)。2.2主要问题 牵引型卷帘机的启动和传动装置一般装在温室顶部,对温室的顶部的建筑结构和强度要求很高,锯齿形温室不太适用。不选用牵引型卷帘机的主要原因还不仅仅以上的问题。首先,60米长的卷帘轴可由10根标准镀锌钢管(自来水管)焊接而成,但牵引型卷帘机构中卷轴位于顶端,是完全受力杆,所以不可避免会出现中间下凹的情况。其次,传动机构的安装也是一个问题。从减速机构到卷帘轴的传动无法实现。如果将链轮安装在卷帘轴的最外端又会出现第一种情况的问题。关键就在于无法在旋转的卷帘轴的任何部位加一个支承。第三,也是最关键的问题。因为该温室没有坡度,在这种温室上安装牵引式卷帘机构根本就不能实现薄膜上卷的动作。三 课题研究计划与写作提纲(1) 设计步骤:调研收集设计资料根据所给定的参数制定总体设计方案完成总装图及部装图完成零件图编写设计说明书。(2)2013年 2月20日-2013年 2 月 26 日:下达设计任务书,明确任务,熟悉课题,收集资料,上交外文翻译、参考文献和开题报告。2013年 2 月 27 日-2013年4 月 15 日:制定总体方案,绘制总装图草图。2013年4月16 日-2013年 5月 27日:修改并完成总装图及部装图,完成有关零件图的设计。2013年 5 月28日-2013年 6 月5 日:编写设计说明书2013年 6月 6日-2013年6 月 8 日:准备答辩四 参考文献 1.周长吉主编.现代温室工程.北京:化学化工出版社,2003 2.王耀林等主编.设施园艺工程技术.郑州:河南科学技术出版社,2000,10 3.刘步洲等主编.蔬菜塑料大棚的机构和性能.上海:上海科学技术出版社,1982.9 4.冯广和主编.设施农业技术.北京:气象出版社,1997.12 5.尚书旗.董佑福等设施栽培工程技术.北京:中国农业出版社,P189,1999.12 6.贡月玲等.几种不同形式的温室保温覆盖卷帘机.设施园艺,2000年第4期 7.赵树朋等.日光温室单轴牵引型卷帘机设计.石家庄:河北农业大学学报,2002.第25卷第4期 8.胡跃高.农业总论【M】.北京:中国农业大学出版社,2000 9.Physical Modeling of Natural Ventilation Through Screens and Windows In Greenhouses.J.agric.Eggnog Rees.(1998) 70,165-176,Article Number:ag970262 10.濮良贵.纪名刚.机械设计.北京:高等教育出版社,2001 11.王世刚,张春,徐起贺.机械设计实践.哈尔滨:哈尔滨工业大学出版社,2001 12.吴宗泽.机械设计实用手册.北京:中央广播电视大学出版社,1998 13.刘鸿文.材料力学.北京:高等教育出版社,1991 14.甘永力.几何量公差与检测.上海:上海科学技术出版社,2001.4 15.西北工业大学工程制图教研室编.画法几何及机械制图.西安:陕西科学技术出版社,1998 学生签名: 年 月 日指导教师批阅意见(指导教师应对课题研究的思路、方法、对策、措施和预期成效等做出评价,并提出具体的改进意见) 指导教师签名: 年 月 日5 温室卷帘机构设计摘 要文章通过比较分析,提出一种自升降的自驱动型卷帘机构。文章讲述了温室以及配套的卷帘机构的发展历史及今后发展发的趋势,引用了几种温室机构类型及配套的卷帘机构,通过比较分析各种机构的结构,实现过程,安装方法以及经济性,技术性,提出一种新型的自驱动式卷帘机构。该机构与锯齿形温室配套使用,能承担60米长的卷帘的升降工作,上下限位距离3米。通过与计算机的结合作用,能够自动控制升降,并能实现3米限位内任意开度控制。最关键的是启动装置能与卷帘同步升降,减少了安装过程中的麻烦。关键词:温室;卷帘;机构ABSTRACTThe development of greenhouses and curtain was summarized mainly in this article, which was contained various mechanisms of rolling blinds machine, which were used in many kinds of greenhouses widely. Through theres characteristic A new kind of auto controlling rolling blinds machine is overture and designed to realize the tolling blinds which is sixty meters long rise and lower at every position among three meters limit by computers. The novelty was that motivated equipment can rise and lower with the synchronous speed, and then , it could be fixed easily. Key Words: greenhouses; curtain; mechanism 目 录第一章 绪论11.1 国内外温室的发展现状11.2 我国自行设计和引进温室的利用情况11.3 温室的分类1第二章 卷帘机构的发展现状22.1概述22.2卷帘机构的各种机型简述2第三章 总体方案设计5第四章 零部件设计74.1 透明覆盖物的选择74.2 卷轴设计74.3 电动机的选择与计算74.4 减速器的设计94.5 蜗杆轴的设计计算11结束语17致谢18参考文献19附录 20 J.agric.Engng Res. (1998) 70,165-176Article Number. Ag970262Physical Modelling of Natural Ventilation Screens and Windows in GreenhouseWe use a combination of practice and theory research on greenhouse ventilation equipment, is to study greenhouse shutter and Windows service life of the device under low pressure and under different wind and pressure fluctuations. These fluctuations associated with the mean wind speed, average wind speeds are obtained by energy spectrum analysis. It follows that a pressure associated with the mean wind speed, and estimation of gas turbulence on mean wind speed has a big impact. Start the potential relationships between greenhouse ventilation equipment and is based on the groundbreaking research of fluid machinery. On air flow and air pressure and temperature correspond to change this prediction corresponds with data from experimental, by and large, the difference between them is less than 20%.NotationA area,m2 Z height, mCc coefficient accounting for convective effect Z0 surface roughness legth,mCkl Kolmogorov constant (0.5) Cwf friction coefficient Greek symbolCu turbulent kinetic energy constant window angle betwwen the flap of windowand the frame,degF(n) power spectral density ,m2/s confficient of thermal expansion g gravitational acceleration,m/s*s porosity h height ,m k von Karmans constant(0.4)H characteristic depth,m dynamic viscosity,Ns/ m2 L characteristic length ,m wind pressure coefficient n frequency ,HzP pressure of air ,PaP0 mean absolute pressure of air in enclosure ,PaPst stack pressure ,Pa SubscriptsPw wind pressure ,Pa fr flow field Q airflow ,m3/s I inside ru turbulent kinetic energy dissipation rate,m2/s l larger length T absolute temperaturw ,K rmsw root-mean-spure wind velocityu flaid velocity, s smaller length u* friction velocity,m/s st stack V volume w wind Y inertial factor1.Introduction Natural ventilation of greenhouse is an extremely complex process, all parameters of this process depends on the greenhouse (rated value, location and geometry of the window as well as leak areas, and so on) and the external environmental conditions. This phenomenon continued interest can cause natural ventilation in mass and energy imbalances and further serious effects of indoor environments. Since 1954, Morris and Neale1 first on natural ventilation in greenhouse ventilation equipment for experimental studies, it is increasingly taking into account the potential physical effects on ventilation equipment. A few decades later, Baiely2 and Cotton3, and Miguel, along with 4 other experiments demonstrated the plant and greenhouse roof with sunshade NET potential benefits. In recent times, in the fenestration equipment 5 curtain is in order to prevent the entry of insects, thereby reducing use of chemical pesticides. So, research on surface air curtain is also an important issue. Existing on the subject of analysis methods can be broadly classified into the following two ways: (1): the empiricism and semi-empirical methods of research studies on airflow through the 6.13 and curtain 2.5.14. (2): guided by the fluid mechanical formulas of digital solutions. 15.17 belongs to the first type of all models based on the theory that the movement of air driven air circulation between the potential of there is a simple linear relationship. This analysis finds that the greenhouses of indoor air is not compressed, plain pieces of this analysis or based on experience derived from the Bernoulli equation. Despite the simple assumption that in conjunction with specific experiments under the corrective coefficient, is also greatly limits the range of the study results. In the second model, using a digital simulation program to solve the equation of inertia, momentum and energy equations, decision speed, temperature and pressure, and eventually air circulation patterns within the greenhouse. Described in this study are two-fold:(1) Understanding of airflow through the shutter with holes (insulation, shading, pest control) and physical properties of skylights in the Exchange. More important deals with shutter and skylight with holes of factors affecting the service life of the parameter and the poor start.(2) Offer a simple actuarial calculation of the wind and the greenhouse effect formula frame shutter and skylight.2.Theory Unconstrained and constrained fluid movement through hole equipment and physical phenomena indicate that this phenomenon of skylights and skylights or equipment with holes and drive circular motion potential difference of characteristic parameters characteristic parameters. Formula accurately describe this phenomenon must take account of these factors. With the formula in Appendix a. As shown in the Appendix, a skylight or curtain with holes through any airflow and drive potential difference of about, is as follows: (/) Q/ t+ Mu Kp-1Q+ YA-1Kp-1/2| Q| Q+0.5(AHCc2)-1| Q| Q=-A ( pw/H+ pst/H) (1) and Q=A which, Q is flow, is gas density, a, is work area, is gas power viscosity, is material of hole product rate (units volume holds fluid of volume), Kp is material of penetration degrees (fluid through media body of capacity), Cc said convection effect coefficient, h is penetration parameter, PW is wind pressure poor, pst is and temperature related of pressure poor, y in Appendix a, in the has defines. In order to facilitate the calculation of air flow through multi-level sealed box or blank space movement, computer networking service must be established. Film sealing area of the greenhouse is a two-story (Figure 1), Figure 2 illustrates the flow theory of networked computing. Physical model for natural ventilation In only one window and roller shutter in greenhouses, network control of the circulating movement is made up of three points, the three contact consists of two resistors are connected together (Figure 2-a). When the roller shutter when there are gaps, network control is made up of three points, but the three points by three resistance threaded together.2.1 Skylights and roller shutter device with holes air flow characteristic parametersAirflow characteristics of permeable materials are divided into porosity and permeability. 18. porosity materials hold the volume of a gas and total material to accommodate gas volume ratio of size between 0 to 1 (0 1). A pore, porosity is 1 ( =1), because the pores are filled with gas. Any permeable material can make use of the gas, the weights and measures of the ability to call it penetration and are consistent with principles of gas motion penetration is not only related to the fluid viscosity and particle diffusion and obstructions when the collision frequency. 18.2 in terms of porous materials, gas molecules of the collision frequency is larger than 103Hz, because gas kinetic viscosity values for 10-5, penetration value that is less than 10-7. and for opening device (Windows, doors), the collision frequency is close to zero so the penetration Kp-. Consistent with the above, connect the two ends (the pores with the larger opening) number is the penetration of Kp. For gap materials, gases can be considered incompressible (1/Cc2 0). By the formula (1) available: (/) Q/ t+ Mu Kp-1Q+ YA-1Kp-1/2| Q| Q=-A ( pw/H+ pst/H) (2) opening ( =1) material penetration Kp-, the formula (1), second and third on the left can be neglected, exporting: Q/ t+0.5 (AHCc2) -1| Q| Q=-A ( pw/H+ pst/H) (3) of the formula (2) is the famous Forchheimer equation, applied to porous materials. Weak gases can be rounded down second and concluded that Darcys law. When the air is stationary publicity (3) simplified Bernoulli equation.2.2 Driving PotentialDriving potential difference is because of airflow caused by temperature difference (static) or wind (causes the air pressure changes) or both roles at the same time. Any one cause can produce a gradient potential stability caused by poor circulation. Wind speed fluctuations will give rise to an additional cycle of movement. Through a greenhouse roof air flow fluctuations can be divided into vibration cycle and Rotary Wo penetration movements. Vibrating circular movement is due to the fluctuation of the wind and indoor air can be compressed. Rotary-Wo penetrating movement is due to the thermal air currents cause rotation of the vortex to seal indoor air impacts.2.2.1 Greenhouse effect on air movementWhen the porous films or blank when there is a temperature difference between inside and outside, there will be a static pressure, which can lead to air movement. Envisage different temperatures on both sides, according to the following equation, pressure on both sides is different: St= g h (4) and = t, expressed many times absolute measurement of temperature difference t and g the gravitational acceleration, h represents a vertical height difference, coefficient of thermal expansion.2.2.2 Effect of wind speed on the air movement (wind)Wind speed is measured does not quantitative. At t time averages and fluctuations of the instantaneous value can be man-made is an integral part of the sum of the values, its w and uw. Within a time interval of average wind speed and wind pressure on (Appendix b): Pw=0.5 ( 2W+uwuw) (5), w and the average wind speed, uw wind speed fluctuations in value. Some anemometer can be read directly out of the square root of the mean wind speed and average wind speed. Say uw have a Gaussian probability distribution, you can simple use the following formulas instead of formula (5): Pw=0.5 2W+ -1urmsw-1 (6), where urmsw is the square root of the mean wind speed. Ordinary cases the anemometer provided only average wind speed readings, therefore, can not only display the average wind speeds, and do not ignore the impact of fluctuations of the wind wind speed meter is very useful. So to average static dynamic wind speed average of the wind speed associated with. Kinetic energy consumption rate ( ) according to the law of Kolmogorov 21:r Mu 2/3=0.75ckl-1F (n) ( w/2 ) 2/3n5/3 (7), f (n) for the energy spectral density, n indicates the frequency, CKL-Kolmogorov constants ( 0.5). Again uses away from surface z distance of kinetic energy turbulence and kinetic energy consumption ratio 21 Zhijian of relationship 0.5 uwuw=c -0.5r k (z+Z0)2/3 (8) wind speed fluctuations of square root value and average of relationship following: uwuw=3 f (n) ( w/2 ) 2/3n5/3 c -0.5r k (z+Z0)2/3 (9) which, k is Mr Frederick FUNG. Kaman constants ( 0.4), c is constants ( 0.99), z for Measure the height of the wind speed, and Z0 is the surface roughness (22 to find value of Z0 in the reference literature). In order to obtain the gamma, make sure f (n) and n is necessary, and the need to implement an energy spectrum analysis method. 23 this energy spectrum analysis method is used to measure the frequency swing variable variances in the process of continuous change. This analysis not only to determine the gamma value, and you can get some extra information to clarify characterization and structure of turbulent fluctuations, and you can determine the frequency of wind field within the main vortex. Wind speed is usually at a reference height measurement. Should export one area coefficient, the coefficient and relative wind wind Domains domain reference high. This coefficient is determined by the atmospheric boundary layer wind speed on the vertical section of the wind decided to follow the wind direction positioning to close .3.Experinmental studyIn order to confirm the potential of fluctuations, while also testing the applicability of the model, we came up with the following experiment. Experiment is to the East in two (E-W) direction construction of greenhouses. Two greenhouse sizes the same (Figure 3): eaves height of 4.5 m, the roof slope angle 22. , 4.1 meters wide, 6.6 meters long. Inside each greenhouse from the ground 2.9 metres with a LS11 insulation panels (Miguel, and the other 18 verify that penetration 7*10-10m2, porosity of 0.99). In the first part of the experiment, each film in greenhouse is qualified. Second part of the experiment, shutter film opened 0.20 m *3.80 m a very small hole in the Middle, which looks like a horizontal crack.Each greenhouse is firmly seal on the wall with insulation Strip, the ground covered with polystyrene foam insulation, in addition to the Windows on the roof, between two Windows each equipped with *0.90 m active strips the size of 2.05 metres. Windows tilt can rise by 30 degrees. Equipped with an aluminum surface of horizontal cylinder-shaped electric heater (two 8-meter, 0.05 m diameter cylinders, arranged in pairs, each of two interval 0.35 meters, each interval of 1.15 m), as shown in Figure 4. In the experiment, heat insulation below the temperature will be different, heaters were used to suppress such temperature changing.Installed in each greenhouse 25 brass nickel-copper alloy thermocouple to measure heat shield and outdoor temperature up or down. They are evenly distributed: 10 thermocouple is distributed below the insulation panels, distribution of 10 at the top, there are 5 exposure outdoors. In order to ensure a fast response 8 (response frequency is approximately 12Hz), thermocouple is made of very fine wires (diameter of about 2.5*10-5 m). Pressure transducers to measure the pressure with a film layer, indoor measurement of upper and lower (each measured three times). Instantaneous measurement of wind pressures on outdoor locations on the skylight 0.20 metres. Measurement of wind speed anemometer with a fast response (response rate of 9.5Hz), skylight 0.20 metres it is placed at a distance, but also measurable. Flow determination using an automated scan of gas equipment. In the experiment, using a constant flow rate and decay rate of 9.25. through the slit air partition amount minus the total fluctuation through the divisions of the fluctuations. In each greenhouse, on the ground with two small fans and barrels full of holes to scan gases (N2O) separated. In the experiment, each within the greenhouse air samples have to be tested in 18 different locations (9 in partition top, 9 screens below), and under the infrared analysis. Two sample test conducted in 32 days between February 1996 and March: (1) flow through the greenhouse roof and curtain is produced by the wind. Trials should be indoor and outdoor temperature difference less than 2 0.5oC, under the wind speed is higher than 1.5 meters per second. (2) flow through the porous rectangular slits on the shutter and the shutter (0.02 m *3.80 m) simply because the shutter of the upper and lower temperature (under steady conditions). In order to reduce the effects of wind pressure, determination to close all the Windows (the Lee side of window opening 2O). First part of the experiment (air is the role of the wind), wind speed and temperature difference between indoor and outdoor gathering in the presence of data 8HZ in the frequency within 10 minutes. Second part of the experiment (air is slowly gathering), shutter upper and lower temperature stability ( t 1 oC) data collection frequency is under 1.66*10-2HZ (per 60 seconds), acquired under stable conditions.4.Results and discussion4.1 wind velocity and wind pressureAcquisition of spectrum analysis is the wind speed in 10 minutes frequencies are under 8HZ conditions. Sampling frequency is available through the determination of the highest frequency, that is half the sampling frequency (the Nyquist frequency) in this experiment, the 4HZ. Due to the characteristics of wind in the Leeward and Windward will be different, spectral analysis to 9 respectively in two places. Findings of the window in the closed greenhouse painted figure, as shown in figures 5 and 6.Figure 5. Three different wind speeds of power spectral density of wind speed: 1.27m/s (*) 3.49m/s (o), 5.50m/s (+) on the windward side measured from the roof of 0.20 metres (-five-thirds angle) as shown in Figure 5 for the three different wind speeds of power spectral density of wind speed: 1.27m/s,3.49m/s,5.50m/s, Windward 0.20 metres measured from roofs.Figure 6. Wind of 0.52m/s (*) 2.24m/s (O), 3.37m/s (+), on the Leeward side away from the roof of 0.20 metres measured power spectrum density (inclination- -5/3) As shown in Figure 6 to Lee the power spectral density of wind speed measured (wind of 0.52m/s,2.24m/s,3.37m/s, measured in the Lee side away from the roof of 0.20 metres). As depicted in Figure 5 and Figure 6, balanced distribution of energy spectrum, frequency/energy-five-thirds range, in line with the law of Kolmogorov. Similar access to windward and Leeward wind energy spectrum. Two major fluctuations in the energy spectrum at frequencies below 0.1,0.2HZ of the highest point, more frequently than 1HZ nothing special, low frequency domain dominated by the wind. In fact, the wind speed in the major energy vortex in the low frequency range. Proving the Kaimal Bot.8 and 26 research theory. Parameter can be Figure 5 figure 6 energy spectral density and frequency values calculated. Calculation of surface roughness: 0.04 m 22, results as shown in table 1.4.2 Through the curtain and window airTo flow just as caused by the temperature difference (that is, for stable temperature conditions Q/ t 0) as depicted in the figure 7 and Figure 8 (p w 0).Figure 7. Air through the shutter corresponding to the formula (2) and (4) budget rolling temperature difference (measurement data (*)Figure 8. Air through the rectangular slit shutter Centre corresponds to the formula (3) and (4) budget rolling temperature difference (measurement data (*) as shown in Figure 7 to air through the shutter corresponding to the formula in the experiment (2) and (4) shutter temperature difference of the budget. Figure 8 shows the experiment in the air through the rectangular slit shutter Centre corresponds to the formula (3) and (4) shutter the temperature difference of the budgets. Caused by airflow just because the wind speed ( 0), as shown in Figure 9-11. In the diagram, air through the skylight or curtain and porous partition by the formula (2) value of the skylight by the formula (3) corresponds to the value.Figure 9. Prediction of air through the Windward (*) and the Lee side (O) with the Windward relative pressure (window-4O)Figure 10. Prediction of air through the Windward (*) and the Lee side (O), as opposed to the Lee side of pressure (open the window-4O)Figure 11. Predict the relative pressure of air through the barricades and Windward (any one window open, window-20o) Windward (*), the Lee side (O)Figure 12. Forecast airflow through clapboard Center narrow sewing and upwind surface of relative pressure (any surface has a fan window open, opened window degrees for 20o) upwind surface (*), Leeward surface (O) Figure 9 by shows for experimental in the forecast airflow through upwind surface (*) and Leeward surface (O) Shi and upwind surface of relative pressure (opened window degrees for 4O) Figure 10 by shows for experimental in the forecast airflow through upwind surface (*) and Leeward surface (O) Shi and Leeward surface of relative pressure (opened window degrees for 4O) Figure 11 shows the experimental forecast relative pres
收藏