亚洲免费av电影一区二区三区,日韩爱爱视频,51精品视频一区二区三区,91视频爱爱,日韩欧美在线播放视频,中文字幕少妇AV,亚洲电影中文字幕,久久久久亚洲av成人网址,久久综合视频网站,国产在线不卡免费播放

        ?

        Research and optimization on the venturi tube dynamic throttling element of new flowmeter

        2015-12-19 08:48:33JianmeiDINGHaiWANGCollegeofMechanicalandElectricalEngineeringNortheastForestryUniversityHarbin150040China
        機(jī)床與液壓 2015年12期
        關(guān)鍵詞:文丘里林業(yè)大學(xué)節(jié)流

        Jian-mei DING,Hai WANG(College of Mechanical and Electrical Engineering,Northeast Forestry University,Harbin 150040,China)

        Research and optimization on the venturi tube dynamic throttling element of new flowmeter

        Jian-mei DING*,Hai WANG
        (College of Mechanical and Electrical Engineering,Northeast Forestry University,Harbin 150040,China)

        According to the working process of dynamic throttling element flowmeter,the Reynolds number keeps constant when the flow is steady.The way to change the pressure drop is to change the local pressure loss.Based on the Fluent software,it has been analyzed that how the structure parameters of venturi tube influence the pressure drop.With the completion of flowmeter prototype,the dynamic throttling element was tested by using a kind of binary flow calibration platform.According to the test results,it could conclude that the optimization could perfectly meet the real flow condition.

        Flowmeter,Venturi tube,Pressure drop

        Hydromechatronics Engineering

        http://jdy.qks.cqut.edu.cn

        E-mail:jdygcyw@126.com

        1 Introduction

        The small diameter of pipeline and impurities in our heating supply system makes the normal flowmeters hard to work,such as vortex flowmeter,turbine flowmeter,electromagnetic flowmeter and the differential pressure flowmeter with holes.To meet the demand of heat metering,we design a kind of new flowmeter based on dynamic throttling element.The core component of the flowmeter is a venturi tube with two metal diaphragms.A very important parameter which affects the performance of the new flowmeter is the pressure drop between inlet pressure and outlet pressure,so we focus on the throttling performance of venturi tube.With the help of Fluent software,we analyze the parameters which affect the pressure drop,and obtain a kind of venturi tube which could be used in the new flowmeter.

        2 Technology analysis

        The schematic shown in Fig.1 is the working status of dynamic throttling element.

        When the fluid flows through the dynamic throttling element,a pressure drop will occur.At the same time,the fluid will impose a driving force to the dynamic throttling element.So we can calculate the flow rate by detecting the driving force.Because the pressure drop is produced by the dynamic throttling element,the key point is to analyze how the dynamic throttling element affects the pressure drop.

        Fig.1 Working status of dynamicthrottIing eIement

        As we can see from Fig.1,the venturi tube is made up with a contraction tube and an expansion tube.According to the principle of fluid dynamics,the pressure drop ΔP generated by the throttling element could be divided into two parts,the friction pressure loss ΔPfand the local pressure loss ΔPl.For the application of engineering,we assume that the two kinds of pressure losses could be calculated,respectively.So we can get the relationship as shown in the Eq.(1):

        The friction pressure loss could be calculated by the original cross-section without deformation.The parameters which affect the friction pressure loss are listed as follows:the diameter of pipeline d,the length of pipeline l,the average rough height e,the average flow velocity v,fluid density ρ,and the viscosity coefficient μ,as shown in the Eq.(2):

        Where,f is the friction pressure loss coefficient,f is the function of Reynolds number Re and relative roughness e/d.

        In the heating supply system,the Reynolds number is in the range of 5 000<Re<50 000.According to the Stanton Chart,the average rough height e has nothing to do with the friction pressure loss coefficient.So only the Reynolds number affects the friction pressure loss coefficient,as shown in the Eq.(3):

        The Reynolds number Re could be determined by the flow,so the friction pressure loss is completely determined by the flow in the new flowmeter.

        Local pressure loss is generated by the deformed cross-section,as shown in the Eq.(4):

        Where,ξ is the so-called local pressure loss coefficient,this value is mainly determined by the structural parameters of the element which affect the local pressure loss.The Reynolds number and average rough height do hardly affect ξ.The structural parameters of venturi tube are the diameter ratio β=D/d,the contraction angle α and expansion angle θ[2].

        In a word,the Reynolds number keeps constant when the flow is steady,so the way to change the pressure drop is to change local pressure loss.Therefore,we mainly analyze how the structural parameters affect the pressure drop.

        3 Simulations based on Fluent

        By changing different parameters,we can build different 3-D models of flow flied in new flowmeter with the help of Solidworks software.Firstly,import the models into the pretreatment software(Gambit)of Fluent;secondly mesh the models and set boundary condition;finally,import the models into fluent 3D solver to compute.

        Boundary condition.In the heat supply system,Reynolds number is usually greater than 4 000.So the fluid in the flowmeter is turbulent.According to Reynolds number,we select the k-ε double function model as the turbulence computation model.Because water is a kind of incompressible fluid,we set inlet velocity as the inlet condition,outflow as the outlet condition,and the wall as the cylindrical and conical surface[3].Under the inlet condition of turbulence,we need to determine turbulence parameters.Turbulence parameters could be calculated as follows.

        Firstly,the turbulence intensity I could be determined as shown in the Eq.(5):

        The turbulence length scale could be evaluated in the Eq.(6):

        Where,L is the hydraulic diameter,the hydraulic diameter of circular pipeline is the inner diameter of pipe.

        Secondly,the turbulence kinetic energy k could be obtained by the average flow velocityˉu and the turbulence intensity I as shown in the Eq.(7):

        Finally,we can obtain the turbulent dissipation rate ε as shown in the Eq.(8).

        Where,Cμis an empirical constant and it has the value of 0.09.

        Under different flow,the turbulence parameters can be listed as Table 1.

        TabIe1 The turbuIence parameters

        CaIcuIation resuIts.Fig.2 shows the relationships between the diameter ratio β and the pressure drop. Where,the flow remains 1 500 kg/h,the contraction angle is 20°,the expansion angle is 10°,the diameter of inlet pipeline is 20 mm.According to Fig.2,we can obtain that the smaller β,the larger pressure drop.Basically the relationship is a negative four function.

        Fig.2 The reIationship between the diameter ratioβ and the pressure drop

        Fig.3 shows the relationships between the contraction angle α and the pressure drop.Where,the flow remains 1 500 kg/h,the diameter ratio β is 0.5,the expansion angle is 10°,the diameter of inlet pipeline is 20 mm.According to Fig.3,the pressure drop varies little when the contraction angle is less than 40°,so we can ignore the change of pressure drop.With the contraction angle α becoming greater but less than 160°,the pressure drop generated by the venturi tube starts to become greater.Basically,the relationship is a linear function.When the contraction angle is greater than 160°,the pressure drop varies little.

        Fig.3 The reIationship between contraction angIeα and the pressure drop

        Fig.4 shows the relationships between the expansion angle θ and the pressure drop.Where,the flow remains 1500 kg/h,the diameter ratio β is 0.5,the contraction angle is 20°,the diameter of inlet pipeline is 20 mm.According to Fig.4,the pressure drop varies little when the expansion angle is less than 30°,so we can ignore the change of pressure drop.With expansion angle θ becoming greater but less than 120°,the pressure drop generated by the venturi tube change to be greater.Basically,the relationship is a linear function.When the contraction angle is greater than 120°,the pressure drop varies little.

        Fig.4 The reIationship between the expansion angIe θand the pressure drop

        Design and simuIation of dynamic throttIing eIement.When the contraction angle is less than 40° and the expansion angle is less than 30°,the pressure drop change little.So we select the contraction angle and the expansion angle of the new flowmeter with good manufacturability.Finally,the contraction angle is chosen to be 20°,the expansion angle is chosen to be 10°.Analyze the different pressure drop under different flow circumstance by using the Fluent software. At last,draw a flow-pressure drop curve based on the analysis results,as shown in Fig.5.

        Fig.5 The fIow-pressure drop curve

        4 Experimental results and analysis

        Make a venturi tube with the structural parameters listed in the former chapter,and fix the venturi tube to the new flowmeter.Test the performance of new flowmeter by using a kind of binary flow calibration platform[4].Acquire the different height of front pressure pipe and behind pressure pipe.Calculate the pressure drop with height differences.Draw the flowpressure drop curve as shown in Fig.6.

        Fig.6 The test resuIt of fIow-pressure drop curve

        Compare the Fig.5 with the Fig.6,we can find that the theoretical curve of flow-pressure drop is slightly less than the testing curve.The reason is that there is pipe connectors between the front pressure port and the behind pressure port,thus the error could be introduced to the final result,but the error will become smaller as soon as the flow is getting smaller.

        5 Summary

        With the simulation of Fluent software,we found the relationships between structural parameters and pressure drop for flowmeter.According to the theoretical analysis,the structure of dynamic throttling element could be optimized.Finally,compare the theoretical analysis with the experimental results,and the difference between could be explained.The results verify the correctness of numerical analysis,and have real meaning for the development of new flowmeter.

        [1]Zhu Y K.Hydromechanics Basis[M].Beijing:Beihang University Press,1990.

        [2]Sun W Q,Wang J Z.Designing Handbook of throttling element in flow measurement[M].Chemical Industry Press,2004.

        [3]Wang F J.Analysis of Computational Fluid Dynamics:Principles and Applications of CFD Software[M].Beijing:Tsinghua University Press,2004.

        [4]Lian X.Experimental Study on New Dynamic Throttling Flow of Central Through Holes[D].Harbin:Harbin Institute of Technology,2011.

        新型流量計(jì)動(dòng)態(tài)節(jié)流元件文丘里管的研究與優(yōu)化

        丁建梅*,王 海
        東北林業(yè)大學(xué)機(jī)電工程學(xué)院,哈爾濱 150040

        根據(jù)動(dòng)態(tài)節(jié)流元件流量計(jì)的工作過程,在雷諾數(shù)保持不變時(shí)流動(dòng)是穩(wěn)定的,改變流量壓降可測(cè)得流量計(jì)局部壓力損失?;贔luent軟件,分析了文丘里管的結(jié)構(gòu)參數(shù)對(duì)壓降的影響,并根據(jù)供熱系統(tǒng)的實(shí)際情況選擇了一組元件匹配合理的文丘里管參數(shù)。流量計(jì)樣機(jī)完成后,通過使用二進(jìn)制流量校準(zhǔn)平臺(tái)測(cè)試動(dòng)態(tài)的節(jié)流元件。根據(jù)試驗(yàn)結(jié)果,優(yōu)化也能較好地滿足實(shí)際流動(dòng)的條件。

        流量;文丘里管;壓力差

        10.3969/j.issn.1001-3881.2015.12.002Document code:A

        TH814

        20 December 2014;revised 6 February 2015;accepted 11 March 2015

        *Corresponding author:Jian-mei DING,Professor.

        E-mail:djm801@126.com

        猜你喜歡
        文丘里林業(yè)大學(xué)節(jié)流
        文丘里洗滌器在凈化粗煤氣中的應(yīng)用及優(yōu)化
        云南化工(2023年6期)2023-07-04 01:35:20
        《南京林業(yè)大學(xué)學(xué)報(bào)(自然科學(xué)版)》征稿簡(jiǎn)則
        《南京林業(yè)大學(xué)學(xué)報(bào)(自然科學(xué)版)》征稿簡(jiǎn)則
        天然氣井井下節(jié)流器研究現(xiàn)狀及應(yīng)用前景
        《南京林業(yè)大學(xué)學(xué)報(bào)(自然科學(xué)版)》征稿簡(jiǎn)則
        《南京林業(yè)大學(xué)學(xué)報(bào)(自然科學(xué)版)》征稿簡(jiǎn)則
        超高壓氣井井下節(jié)流技術(shù)應(yīng)用和設(shè)計(jì)方法
        高溫高壓飛灰過濾器文丘里管故障原因分析及應(yīng)對(duì)措施
        化工管理(2020年10期)2020-04-30 10:20:36
        文丘里管在國(guó)六排放標(biāo)準(zhǔn)中的應(yīng)用分析
        北京汽車(2019年3期)2019-07-19 01:44:08
        PR方程模擬節(jié)流效應(yīng)的數(shù)值研究
        山東化工(2019年12期)2019-07-05 08:44:26
        国产精品农村妇女一区二区三区 | 亚洲av无码久久精品蜜桃| 久久久久99精品国产片| а的天堂网最新版在线| 国产成人av区一区二区三| 久久亚洲精品情侣| 精品久久人人爽天天玩人人妻| 国产精品一区二区三区精品 | 人妻少妇一区二区三区| 日韩精品免费观看在线| 色大全全免费网站久久| 国产精品免费精品自在线观看| 亚洲毛片αv无线播放一区| 日本岛国一区二区三区| 亚洲一区二区在线观看网址| 亚洲人午夜射精精品日韩| 亚洲欧洲国产日产国码无码| 中文字幕日韩一区二区不卡| 未满十八18禁止免费无码网站| 亚洲乱码中文字幕综合| 乱人伦中文字幕在线不卡网站 | 精品国产精品三级在线专区| 草草浮力影院| 久久天天爽夜夜摸| 国产在线播放免费人成视频播放 | 伊人中文字幕亚洲精品乱码| 国产情侣久久久久aⅴ免费| 欧美激情中文字幕在线一区二区| 亚洲精品一区二区三区四区| 国产亚洲精品美女久久久m| 无码人妻精品一区二区三区免费| 久久久久久久久久91精品日韩午夜福利| 少妇人妻无奈的跪趴翘起| 99久久精品午夜一区二区| 欧美精品在线一区| 日本高清人妻一区二区| 国产亚州精品女人久久久久久| 精品国产一区二区三区久久狼| 国产人禽杂交18禁网站| 亚洲国产一区二区三区精品| 久久久久人妻精品一区蜜桃|