机械毕业设计490英文翻译外文文献翻译490
收藏
资源目录
压缩包内文档预览：(预览前20页/共33页)
编号：531697
类型：共享资源
大小：534.63KB
格式：ZIP
上传时间：2015-11-25
上传人：QQ28****1120
认证信息
个人认证
孙**（实名认证）
辽宁
IP属地：辽宁
6
积分
- 关 键 词：
-
机械毕业设计英文翻译
- 资源描述：
-
机械毕业设计490英文翻译外文文献翻译490,机械毕业设计英文翻译
- 内容简介：
-
Z. Tan, Y. Zhang, and S. Ford. “Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling”. Agricultural Engineering International: the CIGR Journal of Scientific Research and Development. Manuscript BC 03 007. Vol. V. December 2003. 1Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling Z. C. Tan, Y. Zhang, S. E. Ford Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, 1304 West Pennsylvania Avenue, Room 332, Urbana, Illinois 61801. Phone: (217) 244-6316, Fax: (217) 244-0323. Email: ztan1 Abstract Within this study the decay speed of centrifugal device induced rotational airflow in round ducts and its conditioning for dust concentration measurement was investigated. Tests were conducted under room conditions at average Reynolds numbers within the range of 0.71.14x105. Duct diameters were 152 mm and 203 mm. Airflow in the ducts was found nonuniform and unsteady within the axial location to diameter ratio (x/D) of 10.5. The nonuniformity of axial airflow was nearly independent of the average Reynolds number. The study proved that it is impractical to decay the rotational airflow simply by using straight extension duct. A flow conditioner with minimal particle loss is needed to make the air flow uniform and steady. As a case study, a simple flow conditioner was tested. It decayed the rotational airflow to an acceptable level within x/D=2. The measured dust concentrations at 5 radial locations at x/D=2 were uniform: s/m2/3) is always less than 0.1. The experimental results here show that airflow approached uniformity level of 0.05 (5%) after x/D=1.5. On the other nts Z. Tan, Y. Zhang, and S. Ford. “Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling”. Agricultural Engineering International: the CIGR Journal of Scientific Research and Development. Manuscript BC 03 007. Vol. V. December 2003. 9hand, even with a flow conditioner, it is not recommended to take samples right after the conditioner. Taking samples at x/D1.5 after the flow conditioner is a safe choice, unless it is impractical like in the situations reported by Marsh et al. (2003). The fitting curve gives the relationship between s/V and x/D as, =Vs 0.081-0.33 Dx (R2=0.89) (4) 0.00.40 3 6 9 12x/Ds/V w/o Flow Cond.With Flow Cond.Figure 7. Nonuniformity of velocity over x/D for flow with and without flow conditioner (V is the average velocity, s is standard deviation of velocity. x/D is the axial location over diameter of the duct) 4. Steadiness Another parameter to evaluate the effect of the flow conditioner is flow steadiness. In this paper steadiness of the flow is characterized using centerline dimensionless velocity, Vc/V. Where, Vc is air velocity at the centerline, and m is the average velocity at x/D. It shows the velocity change along the duct. For tested conditions without flow conditioner, the centerline axial velocity keeps increasing along the duct length (see Figure 5). Figure 8 gives an example when average Reynolds number is 1.14x105. It shows that the centerline velocity approached the average velocity as x/D increased. For airflow without flow conditioner, the axial velocity kept increasing and approaching steady state, but it did not reach steady state within our test conditions (x/D50 (tested) x/D=200 (Predicted from fitting equation) x/D=90 (tested) x/D10. (x/D2 with flow conditioner) Table 1 shows that rotational flow exists in many general engineering applications. Rotational flow could be created by, but not limited to, 1) bending vanes, such as vanes used in cyclones, 2) sudden changes in flow direction, including 90o bends (McManus et al. 1985) and double 90o elbows (Laribi et al., 2001), and 3) air flow downstream of a centrifugal device such as a centrifugal fan. The rotational airflow will affect the accuracy in airflow rate measurement using an orifice meter (Laribi et al., 2001) as well as dust concentration measurements using isokinetic sampling techniques, as addressed in this paper. nts Z. Tan, Y. Zhang, and S. Ford. “Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling”. Agricultural Engineering International: the CIGR Journal of Scientific Research and Development. Manuscript BC 03 007. Vol. V. December 2003. 13Summary and Conclusions This research investigated decay of centrifugal device created rotational airflow in round ducts under room condition. An example velocity profile was first given to visualize the airflow inside the ducts with and without flow conditioner. Then the uniformity and steadiness of the airflow were compared. As a case study, the dust concentration distribution after the flow conditioner was presented. The following conclusions can be drawn from this study: 1. Centrifugal device has negligible effect in creating rotational flow on upstream airflow in round ducts. The same device can create very strong nonuniform and unsteady rotational airflow in downstream ducts. 2. Once a rotational airflow is created in a duct, it is impractical to lessen it to an acceptable level simply by using long ducts. 3. The nonuniformity parameter of the airflow at certain point in a duct is nearly independent of the average Reynolds number. When s/m0.05, the airflow is considered uniform. 4. A simple flow conditioner can significantly reduce the airflow swirl. The flow conditioner with length to diameter ration (L/D) of 2 lessens the rotational airflow to an acceptable level quickly within x/D=2. Duct concentrations at 5 radial locations at x/D=2 downstream the conditioner was observed uniform (s/m0.01). On the other hand, it is not recommended to take samples right after the flow conditioner. References ANSI/ASME MFC-1M-1979. Glossary of terms used in the measurement of fluid flow in pipes. ANSI/ASHRAE Standard 52.2-1999. Method of testing general ventilation air-cleaning devices for removal efficiency by particle size. Carpenter, G. A. 1986. Dust in Animal indoor environments-Review of Some Aspects, Journal of Agricultural Engineering Research. 33: 227-241. Crook, B. 1995. Inertial samplers: biological perspectives, in Bioaerosols Handbook (edited by Cox and Wathes), chapter 9, Florida: CRC Press, Inc. Hinds, W. C. 1999. Aerosol Technology: Properties, Behavior and Measurement of Airborne Particles. New York: Wiley. Kreith, F. and O. K. Sonju. 1965. The decay of a turbulent swirl in a pipe. Journal of Fluid Mechanics. 22(2): 257-271. Lacey, L. and J. Venette. 1995. Outdoor air sampling techniques, in Bioaerosols Handbook (edited by Cox and Wathes), chapter 16, Florida: CRC Press, Inc. nts Z. Tan, Y. Zhang, and S. Ford. “Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling”. Agricultural Engineering International: the CIGR Journal of Scientific Research and Development. Manuscript BC 03 007. Vol. V. December 2003. 14Laribi, B., Wauters, P., and M. Aichouni. 2001. Experimental study of the decay of swirling turbulent pipe flow and its effect on orifice meter performance. Proceedings of the FEDSM2001, 2001 ASME Fluid Engineering Conference. May 29-June1, 2001. New Orleans, USA. FEDSM2001-18039: 93-96. Marsh, L. S., S. W. Gay, G. L. Van Wicken, and T. Crouse. 2003. Performance evaluation of the SanScent air scrubber for removal of dust, ammonia, and hydrogen sulfide from the exhaust air of a swine nursery. ASAE paper #034052. ASAE 2003 annual meeting. July 27-30, 2003. Las Vegas, NV. McManus, S. E., B. R. Bateman, J. A. Brenham, I. V. Pantoja, and D. Mann. 1985. The decay of swirling gas flow in long pipes. American Gas Association Operating Section Distribution/Transmission Conference, Boston, MA. May 1985. Talbot, L. 1954. Laminar swirling pipe flow. Journal of Applied Mechanics. Transactions of ASME. 21(76): 1-7. Wang, L., C.B. Parnell and B.W. Shaw. 2002. Performance Characteristics of Cyclones in Cotton-Gin Dust Removal. Agricultural Engineering International: the CIGR Journal of Scientific Research and Development. Volume IV. Manuscript # BC 02 001. Zhang, Y., X. Wang, G. L. Riskowski, S. E. Ford, and L. L. Christianson. 2001. Particle separation efficiency of a uniflow deduster with different types of dusts. ASHRAE Transactions. 107 (2): 93-98. Nomenclature dp Particle diameter (mm) D Duct diameters (m) l Characteristic dimension (m) L Length of the duct, length of the flow conditioner (m) r Radial location (m) R Radius of the duct (m) r/R Dimensionless radial location Re Reynolds numbers V Average fluid velocity (m/s) Vc Velocity along the center line (m/s) Vr Velocity at radial location at r (m/s) x Axial location of the duct (m) x/D Axial location to diameter ratio s Standard deviation of velocity (m/s), particle concentration (number/cm3) m Average value particle concentration (number/cm3) s/m Non-uniformity of velocity or particle concentration v Kinematic viscosity of the fluid (m2/s). nts内蒙古科技大学毕业设计外文翻译 _ Z. Tan, Y. Zhang, and S. Ford. !Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling!. Agricultural Engineering International: the CIGR Journal of Scientific Research and Development. Manuscript BC 03 007. Vol. V. December 2003. Z.C. 谭， Y.张， S.E.福特 !为测量粉尘浓度，在具有旋转气流衰变和流量调节器的大直径管道中使用等速采样 !国际农业工程：国际 农业工程学会杂志科学的研究和发展。公元前 2003年 12 月手稿第 5 卷， 编号 03 007 。 Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling Z. C. Tan, Y. Zhang, S. E. Ford Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, 1304 West Pennsylvania Avenue, Room 332, Urbana, Illinois 61801. Phone: (217) 244-6316, Fax: (217) 244-0323. Email: ztan1 Abstract Within this study the decay speed of centrifugal device induced rotational airflow in round ducts and its conditioning for dust concentration measurement was investigated. Tests were conducted under room conditions at average Reynolds numbers within the range of 0.7-1.14x105 . Duct diameters were 152 mm and 203 mm. Airflow in the ducts was found nonuniform and unsteady within the axial location to diameter ratio (x/D) of 10.5. The nonuniformity of axial airflow was nearly independent of the average Reynolds number. The study proved that it is impractical to decay the rotational airflow simply by using straight extension duct. A flow conditioner with minimal particle loss is needed to make the air flow uniform and steady. As a case study, a simple flow conditioner was tested. It decayed the rotational airflow to an acceptable level within x/D=2. The measured dust nts内蒙古科技大学毕业设计外文翻译 _ Z. Tan, Y. Zhang, and S. Ford. !Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling!. Agricultural Engineering International: the CIGR Journal of Scientific Research and Development. Manuscript BC 03 007. Vol. V. December 2003. Z.C. 谭， Y.张， S.E.福特 !为测量粉尘浓度，在具有旋转气流衰变和流量调节器的大直径管道中使用等速采样 !国际农业工程：国际 农业工程学会杂志科学的研究和发展。公元前 2003年 12 月手稿第 5 卷， 编号 03 007 。 concentrations at 5 radial locations at x/D=2 were uniform: /2/3) is always less than 0.1. The experimental results here show that airflow approached uniformity level of 0.05 (5%) after x/D=1.5. On the other hand, even with a flow conditioner, it is not recommended to take samples right after the conditioner. Taking samples at x/D1.5 after the flow conditioner is a safe choice, unless it is impractical like in the situations reported by Marsh et al. (2003). The fitting curve gives the relationship between /V and x/D as, nts内蒙古科技大学毕业设计外文翻译 _ Z. Tan, Y. Zhang, and S. Ford. !Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling!. Agricultural Engineering International: the CIGR Journal of Scientific Research and Development. Manuscript BC 03 007. Vol. V. December 2003. Z.C. 谭， Y.张， S.E.福特 !为测量粉尘浓度，在具有旋转气流衰变和流量调节器的大直径管道中使用等速采样 !国际农业工程：国际 农业工程学会杂志科学的研究和发展。公元前 2003年 12 月手稿第 5 卷， 编号 03 007 。 0 .3 30 .0 8 1 xVD 2 0.89R 4 Figure 7. Nonuniformity of velocity over x/D for flow with and without flow conditioner (V is the average velocity, is standard deviation of velocity. x/D is the axial location over diameter of the duct) 4. Steadiness Another parameter to evaluate the effect of the flow conditioner is flow steadiness. In this paper steadiness of the flow is characterized using centerline dimensionless velocity, Vc /V. Where, Vc is air velocity at the centerline, and is the average velocity at x/D. It shows the velocity change along the duct. For tested conditions without flow conditioner, the centerline axial velocity keeps increasing along the duct length (see Figure 5). Figure 8 gives an example when average Reynolds number is 1.14x105 . It shows that the centerline velocity approached the average velocity as x/D increased. For airflow without flow conditioner, the axial velocity kept increasing and approaching steady state, but it did not reach steady state within our test conditions (x/D2/3）总是小于 0.1，实验结果表明，在经x/D=1.5 之后 气流接近均匀标准的 0.05（ 5%）。在另一方面，即使以流量调节器不建议采取经过调节后的样本。流量调节器在 x/D1.5时获取样本是一个安全的选择，除非它是像玛稀等人（ 2003）报告中的形势 一样不切实际。拟合曲线 /V 和 x/D给出的关系， 0 .3 30 .0 8 1 xVD 2 0.89R 4 图 7.对于用与不用流量调节器，超过 x/D时速度的不均匀性（ v是平均速度，是标准偏差速度， x/D是超过导管直径的轴向位置） 4. 稳定性 另一个 参数是评价流量调节器对流量 稳定性的影响，在本文中流量稳定性的特点是采用中线 Vc /V 的无因此速度，在中线处 Vc 是空气的 速度，也是在 x/D处平均速度，它显示出长导管中速度的变化。在没有流量调节器的实验条件下，nts内蒙古科技大学毕业设计外文翻译 _ Z. Tan, Y. Zhang, and S. Ford. !Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling!. Agricultural Engineering International: the CIGR Journal of Scientific Research and Development. Manuscript BC 03 007. Vol. V. December 2003. Z.C. 谭， Y.张， S.E.福特 !为测量粉尘浓度，在具有旋转气流衰变和流量调节器的大直径管道中使用等速采样 !国际农业工程：国际 农业工程学会杂志科学的研究和发展。公元前 2003年 12 月手稿第 5 卷， 编号 03 007 。 沿长导管中心线的轴向速度不断增加（见图 5）。 图 8.给出当平均 雷诺数 为 1.14x105 时的一个实例，它表明中线的速度接近当 x/D增加时的平均速度。对于没有流量调节器的气流，轴向速度不断增加，并接近稳定状态。但在我们的实验条件下（ x/D10.5），它并没有达到稳定状态。对于经过调节后的流量，在 x/D=1.5后，中心线速度的数值很 快达到平均速度。它表明流量调节器使得旋转空气流快速的接近稳定状态。 图 8.对于流量有无流量调节器稳定性超过 x/D（ Vc/V是在中线以上的平均速度超过导管直径的轴向位置 x和 x/D处的速度） 总之，实验证明，它是通过使用简单的长导管使导管中衰变的旋转气流达到可接受的标准是不现实的。 5. 微粒浓度稳定性和一致性 通过标准偏差超过平均浓度 ( / )的 10 个样本，在图 1 显示的每一个位置的稳定性特点。在图 9 中所示的 每 5 个位置的微粒浓度的稳定性。对于每个位置，在曲线中看出，平均微粒 浓度小于 15%与大多数不到 10%的标准偏差。转台的稳定性可能有助于这一变化。 nts内蒙古科技大学毕业设计外文翻译 _ Z. Tan, Y. Zhang, and S. Ford. !Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling!. Agricultural Engineering International: the CIGR Journal of Scientific Research and Development. Manuscript BC 03 007. Vol. V. December 2003. Z.C. 谭， Y.张， S.E.福特 !为测量粉尘浓度，在具有旋转气流衰变和流量调节器的大直径管道中使用等速采样 !国际农业工程：国际 农业工程学会杂志科学的研究和发展。公元前 2003年 12 月手稿第 5 卷， 编号 03 007 。 图 9.流量调节器下游的稳定性（ Re=2.3x105） ( 是标准偏差， 是平均微粒浓度， dp 是微粒直径 ) 在每个径向位置，从 10 个样本中计算一个平均微粒浓度，那么这个平均微粒浓度在径向位置（ x/D=2）是基于 5 个浓度在 5 个径向位置的计算。这个平均微粒大小分布在 x/D=2 如在图 10 中所示。每个误差条标志着相应的标准偏差（ ）。相应的标准偏差超过平均值（ / ），并表现在同一 y 轴方向上。在曲线图上看出，对于小于 10 m的任何微粒， / 小于 10% 。较高的 / 是与较低的微粒浓度相关联的， APS 3321 的采样效率是低的，并引入了错误，这个超出了本文的范围，将另行处理。在质量浓度的基础上，其 5个位置的平均浓度是 =8.42 mg/m3 与 标准偏差为 =0.075 mg/m3 ，这表明 / 小于 1%。 图 10.流量调节器下游的均匀性（ 5个位置， Re=2.3x105） nts内蒙古科技大学毕业设计外文翻译 _ Z. Tan, Y. Zhang, and S. Ford. !Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling!. Agricultural Engineering International: the CIGR Journal of Scientific Research and Development. Manuscript BC 03 007. Vol. V. December 2003. Z.C. 谭， Y.张， S.E.福特 !为测量粉尘浓度，在具有旋转气流衰变和流量调节器的大直径管道中使用等速采样 !国际农业工程：国际 农业工程学会杂志科学的研究和发展。公元前 2003年 12 月手稿第 5 卷， 编号 03 007 。 6. 相对于以往的研究 在本文的研究结果中，扩大了长管道中旋转气流研究的数据库。表 1所示是以前的测试与我们的测试的比较。 表 1 与以往的研究试验条件的比较 表 1所示，在许多一般工程应用中存在着旋流。旋流是可创造的，但不局限于， 1）弯曲叶片，如用于旋风分离器中的叶片， 2）在流动方向的突发性变化，其中包括 90 转弯（麦克马纳 斯 等人 1984 年）和双 90 弯头（ 拉里比等人 ， 2001年 ）以及 3）如离心风机的一个离心设备的下游气流。像在本文中的状态一样，旋转气流将影响采用孔板流量计（ 拉里比等人 ， 2001 年 ）测量气流率以及采用等速取样技术测量粉尘浓度。 总结与结论 这项研究调查了在室内条件下，离心设备的衰变造成在圆形管道中的旋转气流。这个速度剖面是气流在有无流量调节器的管道内给予首次可视化的例子。然而把均匀性和稳定性的气流进行比较，作为一个案例研究，在流量调节器被提出以后粉尘浓度的分布，从本研究中可以得出以下结论 ： 1. 离心设备在圆形管道下游的气流，造成的旋流已微不足道。同样的设备在管道的下游可以创造非常强烈的不均匀和不稳定的旋转气流。 2. 一次旋转气流是在管道中创造的，通过使用简单地长管道以将它减轻到一个可以接受的标准，这是不切实际的。 nts内蒙古科技大学毕业设计外文翻译 _ Z. Tan, Y. Zhang, and S. Ford. !Decay of Rotational Airflow with Flow Conditioner in Larger Diameter Ducts for Dust Concentration Measurement using Isokinetic Sampling!. Agricultural Engineering International: the CIGR Journal of Scientific Research and Development. Manuscript BC 03 007. Vol. V. December 2003. Z.C. 谭， Y.张， S.E.福特 !为测量粉尘浓度，在具有旋转气流衰变和流量调节器的大直径管道中使用等速采样 !国际农业工程：国际 农业工程学会杂志科学的研究和发展。公元前 2003年 12 月手稿第 5 卷， 编号 03 007 。 3. 气流的不均匀参数，在管道中的某一点是不依赖于平均 雷诺数 的。当/ 0.05 时，气流的均匀是可考虑的。 4. 一个简单的流量调节器能够较大的减少气旋，流量调节器的长径比（ L/D）为 2 时，在 x/D=2 处旋转气流迅速的减少到一个可以接受的标准。粉尘浓度在调节器 下游 x/D=2 处的 5 个径向位置观测是一致的 ( / 0.01)。在另一方面，不建议采用经流量调节器纠正后的样本。 参考文献 美国国家标准化组织 /美国机械工程师协会 MFC-1M-1979，用于测量管子中流体流动的术语辞典。 美国国家标准化组织 /美国机械工程师协会 （ ANSI/ASHRAE）标准 52.2-1999，按微粒大小测试一般的通风空气清除设备的消除效率的方法。 木匠， G.A.1986年，粉尘在动物室内某 些方面的环境 -审查， 农业工程研究杂志， 33： 227-241。 克鲁克 （ Crook） , B.1995 年，惯性采样器： 佛罗里达州：华润新闻公司 在生物学气胶手册（主编 考克斯 (Cox) 和 （韦德） Wathes）中，第 9 章，生物学的看法。 Hinds, W. C. 1999 年，气溶胶技术：大气颗粒物的属性、性能和测量。纽约：威利出版社。 Kreith, F. 和 O. K. Sonju. 1965 年，管子中混乱漩涡的衰变。流体力学杂志。 22(2): 257-271。 （兰西） Lacey, L. 和 J. Venette. 1995 年， 佛罗里达州：华润新闻公司 在生物学气胶手册（主编 （考克斯） Cox 和 （韦德） Wathes）中，第
- 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。
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。
川公网安备: 51019002004831号