原文.doc

LZG-30单头螺杆型干式真空泵的建模与仿真【单螺杆】【三维SW】【含CAD图纸】

收藏

资源目录
跳过导航链接。
压缩包内文档预览:
预览图 预览图 预览图 预览图 预览图 预览图 预览图
编号:116487005    类型:共享资源    大小:5.14MB    格式:ZIP    上传时间:2021-03-03 上传人:好资料QQ****51605 IP属地:江苏
45
积分
关 键 词:
单螺杆 三维SW LZG 30 螺杆 型干式 真空泵 建模 仿真 三维 SW CAD 图纸
资源描述:

喜欢这套资料就充值下载吧。。。资源目录里展示的都可在线预览哦。。。下载后都有,,请放心下载,,文件全都包含在内,,【有疑问咨询QQ:414951605 或 1304139763】 ========================================= 喜欢这套资料就充值下载吧。。。资源目录里展示的都可在线预览哦。。。下载后都有,,请放心下载,,文件全都包含在内,,【有疑问咨询QQ:414951605 或 1304139763】 =========================================

内容简介:
Study on the performance prediction of screw vacuum pumpAbstractPumping characteristics of the screw vacuum pump were investigated. The aim of this study was to establish a method of the performance prediction and a way to design the pump that satisfies specific requirements. The performance was analysed by the balance among geometrical pumping speed, net throughput and leaks. The leaks flow through clearances between a screw rotor and a stator, and clearances between two meshing rotors. These leaks were estimated with the results based on the linearised BGK model and the flows through ideal labyrinthes. Experiments were carried out by rotors of 120mm diameter, and pumping speed and ultimate pressure were measured. The comparison between the measurements and the predicted values shows that the present method predicts the performance of the screw pump with a sufficient accuracy for practical applications1. IntroductionIn recent years, screw vacuum pumps have become noticed, since the structure of the pump is simple and liquids or solids are hard to accumulate when sucked with gas or are condensed or solidified in the pump. An analytical model of screw vacuum pump will be useful to design a pump that satisfies specific requirements and to predict pumping characteristics under conditions which differ from the condition designed for. So, we propose an analytical model for the screw vacuum pump. 2. Outline of analytical modellingFig. 1 shows a pair of meshing rotors of the screw vacuum pump. The volume enclosed by a groove of screw, a crest of thread of another rotor and a stator traps gas and transfers it from inlet side to outlet side as the rotors rotate. The model is built by the balance among geometrical pumping speed, net throughput and leaks. Display Full Size version of this image (7K)Fig. 1. Configuration of the meshing rotors of screw vacuum pump. 2.1. Path of leaks inside the screw vacuum pumpThere are three kinds of clearances inside the screw pump, i.e. the clearance between rotor and stator O, the radial clearance between rotors I, and the axial clearance between rotors . In the case of single thread, paths of leaks which come into or out of the third transfer volume (appearing in Fig. 2A) for example, are as follows. Display Full Size version of this image (11K)Fig. 2. Clearance and flowing path of leak: (A) development of a pair of screws; (B) axial clearances. The leak through the axial clearance is considered as a superposition of the major component (represented by the straight arrow in Fig. 2B) and minor component (curved arrow). 2.2. Evaluating method of the leaksWe evaluate the leaks by a compound method. The method is compounded of the flow rate derived from BGK equations and diffuse reflections, and the flow rate of ideal labyrinthes. The leak through the clearance between rotor and stator, and the leak through the axial clearance between rotors are both given in the following form(1)and the leak through the radial clearance between rotors is given by(2)where MP is the mass flow rate of Poiseuille flow between parallel plates, MS mass flow rate through a slit, MC mass flow rate of Couette flow between parallel plates, MRp mass flow rate through a gap between two cylinders induced by pressure difference, MRr mass flow rate through a gap between two cylinders induced by rotation of the cylinders and ML mass flow rate of ideal labyrinthes. We obtained precise information on MP and MS from the studies of Hasegawa and Sone, and Sone and Itakura 3 and 6, respectively. MC is determined by the fact that the dimensionless flow rate equals a half, because of the anti-symmetry of the velocity. MRp and MRr are determined by(3)MRr=IUQRr(4)where RC=1/(1/R1+1/R2), U=(R1+R2). QRp and QRr are obtained by solving the MGL equation 1 by parabolic film approximation 2. The results are shown in Fig. 3. Display Full Size version of this image (4K)Fig. 3. Nondimensional mass flux through the gap between a cylinder and a plane. The axial clearance has a non-uniform gap, as shown in Fig. 4, then we define mean or representative quantity to apply the above evaluation methods. For example,(5)defines mean square clearance, where SM is the area of lens-like domain appearing in Fig. 4. The other definitions appear in the studies of Ohbayashi et al. 4 and 5. Display Full Size version of this image (3K)Fig. 4. Contour of the gap width of the axial clearance. 2.3. Pumping characteristicsAssuming that the pressure changes isothermally, the pressure pi in the ith transfer volume is represented by(6)where V is the volume of one transfer volume, MO leak rate through O, MI leak rate through I, MMb major component of the leak through , MMc minor component of the leak through via the minimum gap and iO,iI,iMb,iMc represent the differences between the number of upstream and downstream transfer volumes corresponding to the clearance or path indexed by subscript. Balance among geometrical pumping speed, net throughput and leaks leads to(7)where Tc represents one cycle of periodic pressure change. In the case that the screws are single threaded, Tc equals /, because the ith transfer volume comes to the (i+1)th position after half rotation. (6) and (7) can be solved under the following periodic condition:pit=0=pi1t=Tc, (i=1,2,3,nm)(8)3. ExperimentExperiments are carried out with a screw vacuum pump whose dimensions are shown in Table 1. Fig. 5a shows the comparison between measurements and analytical predictions relating to pumping speed. Fig. 5b shows the comparison relating to ultimate pressure as a function of rotating speed. The measurements and the predictions for ultimate pressure and pumping speed in the inlet pressure over the 100Pa range are well agreed. Table 1. Dimensions of an experimental screw vacuum pump Display Full Size version of this image (10K)Fig. 5. Comparison between experimental results and analytical predictions: (a) pumping speed vs. inlet pressure; (b) ultimate pressure vs. rotation speed. 4. ConclusionsThe conclusions are summarised as follows: 1. the screw vacuum pump was analysed, and the analytical model of its pumping characteristics was proposed;2. the analytical model was verified through the experiments. This model has satisfying accuracy for
温馨提示:
1: 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
提示  人人文库网所有资源均是用户自行上传分享,仅供网友学习交流,未经上传用户书面授权,请勿作他用。
关于本文
本文标题:LZG-30单头螺杆型干式真空泵的建模与仿真【单螺杆】【三维SW】【含CAD图纸】
链接地址:https://www.renrendoc.com/paper/116487005.html

官方联系方式

2:不支持迅雷下载,请使用浏览器下载   
3:不支持QQ浏览器下载,请用其他浏览器   
4:下载后的文档和图纸-无水印   
5:文档经过压缩,下载后原文更清晰   
关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服 - 联系我们

网站客服QQ:2881952447     

copyright@ 2020-2025  renrendoc.com 人人文库版权所有   联系电话:400-852-1180

备案号:蜀ICP备2022000484号-2       经营许可证: 川B2-20220663       公网安备川公网安备: 51019002004831号

本站为文档C2C交易模式,即用户上传的文档直接被用户下载,本站只是中间服务平台,本站所有文档下载所得的收益归上传人(含作者)所有。人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。若文档所含内容侵犯了您的版权或隐私,请立即通知人人文库网,我们立即给予删除!