内陆核电厂用水系统冷却塔空气动力特性数值模拟研究(中英)(整理)

鼓风式机械通风冷却塔空气动力特性数值模拟研究摘要鼓风式机械通风冷却塔常用于核电厂的重要厂用水系统，但相关设计规范并没有给出冷却塔的空气动力特性计算公式。本文采用FLUENT软件对鼓风式机械通风冷却塔的空气动力进行了数值模拟计算，对冷却塔的设计布置进行了优化，分析总结给出了冷却塔阻力计算公式。结果表明，填料安装位置对鼓风式机械通风冷却塔整塔阻力影响不大，但会影响填料断面风速分布均匀性，填料安装高度越低，风速分布越均匀；出口收缩段的高度越高，整塔阻力越小，风速分布越均匀；出口收缩段与水平的夹角越大，整塔阻力系数越小，但变化趋势不明显，收缩角基本不影响填料断面风速分布均匀性。关键词鼓风式冷却塔；塔型；阻力系数；风速均匀性ABSTRACTTHEFORCEDDRAFTMECHANICALCOOLINGTOWERISALWAYSUSEDINANUCLEARPOWERPLANT,WHILETHERELEVANTDESIGNSPECIFICATIONSHAVENOTFORMULAABOUTTHEAERODYNAMICCHARACTERISTICSOFCOOLINGTOWERTHISPAPERUSESFLUENTSOFTWARETOSIMULATEANDSTUDYTHEAERODYNAMICCHARACTERISTICSOFTHEFORCEDDRAFTMECHANICALCOOLINGTOWER,ANDOPTIMIZETHEDESIGNOFTHECOOLINGTOWER,ANDANALYSISTOSUMMARIZETHECOOLINGTOWERRESISTANCECALCULATIVEFORMULATHERESULTSSHOWTHATTHEHEIGHTOFTHEFILLHASLITTLEEFFECTSONTHEWHOLETOWERRESISTANCECOEFFICIENT,BUTITINFLUENCESTHEWINDVELOCITYDISTRIBUTIONUNIFORMITYOFTHEFILLSECTION,THELOWERTHEPOSITIONIS,THEMOREUNIFORMTHEWINDVELOCITYDISTRIBUTIONISTHECONVERGENTSECTIONHEIGHTISHIGHER,THEWHOLETOWERRESISTANCEISSMALLERANDTHEWINDVELOCITYDISTRIBUTIONISMOREUNIFORMTHEANGLEBETWEENCONVERGENTSECTIONANDHORIZONISBIGGER,THEWHOLETOWERRESISTANCEISSMALLER,WHILETHISTRENDISNOTOBVIOUS,ITDOESNOTAFFECTTHEWINDVELOCITYDISTRIBUTIONUNIFORMITYONTHEFILLSECTIONKEYWORDSTHEFORCEDDRAFTMECHANICALCOOLINGTOWER,TOWERSHAPE,RESISTANCECOEFFICIENT,WINDVELOCITYDISTRIBUTIONUNIFORMITY1研究背景内陆核电厂的重要厂用水的水量不大，但却影响核电厂的安全。鼓风式机械通风冷却塔能较好地适应核电对安全性和抗震性能的要求而常被内陆核电厂采用。鼓风式机械通风冷却塔不仅在通风方式上有别于常规的抽风式机械通风冷却塔，在塔型结构布置上也有明显差异。我国的相关设计规范和资料对鼓风式机械通风冷却塔没有明确的设计计算方法15。为了解塔内气流特性并对塔型进行优化，需要通过相关的研究来确定其空气动力特性。通过物理模型试验来研究冷却塔空气动力特性是一个十分有效的手段，但是由于鼓风式机械通风冷却塔模型本身的复杂性及系统试验的塔型的变化，使模型试验研究工作量和投资都很大。本文利用FLUENT软件建立鼓风式机械通风冷却塔空气动力计算的数学模型，经过与试验结果对比验证，确定模型参数和网格数量。研究了不同塔型条件下塔内气流分布及阻力特性，最终分析总结出了鼓风式机械通风冷却塔的阻力计算公式以及塔型与配风均匀性的关系。阻力系数计算公式与试验结果相比偏差小于5，可为设计提供参考。1RESEARCHBACKGROUNDTHEWATERQUANTITYOFIMPORTANTWATERSYSTEMOFINLANDNUCLEARPOWERPLANTISNOTBIG,BUTITAFFECTSTHESECURITYOFNUCLEARPOWERPLANTTHEFORCEDDRAFTMECHANICALCOOLINGTOWERCANSATISFYTHEREQUIREMENTSOFEQUIPMENTSECURITYANDEARTHQUAKERESISTANCE,SOITWILLBEUSEDMOREANDMOREININLANDNUCLEARPOWERPLANTTHEFORCEDDRAFTMECHANICALCOOLINGTOWERISNOTONLYDIFFERENTFROMTHECONVENTIONALINDUCEDDRAFTMECHANICALCOOLINGTOWERINVENTILATIONWAY,BUTALSOHASDISTINCTDIFFERENCEINTOWERSHAPEANDSTRUCTURELAYOUTCHINASRELEVANTDESIGNSPECIFICATIONSANDINFORMATIONONTHEFORCEDDRAFTMECHANICALCOOLINGTOWERHAVENOCLEARDESIGNMETHODFORUNDERSTANDINGTHEAIRFLOWCHARACTERISTICSOFTHETOWERANDOPTIMIZINGTHETOWERSHAPE,ITSNECESSARYTODOSOMERELEVANTRESEARCHTOREALIZETHEAERODYNAMICCHARACTERISTICSITSAVERYEFFECTIVEWAYTOESTABLISHAPHYSICALMODELTOSTUDYTHEAERODYNAMICCHARACTERISTICSOFTHECOOLINGTOWER,HOWEVER,DUETOTHEFORCEDDRAFTMECHANICALCOOLINGTOWERMODELSCOMPLEXITYANDVARIABILITY,THEWORKLOADOFEXPERIMENTANDINVESTMENTISVERYBIGTHISPAPERUSESFLUENTSOFTWARETOBUILDAMATHEMATICALMODELOFTHEFORCEDDRAFTMECHANICALCOOLINGTOWERTOSTUDYTHETOWERAERODYNAMICCHARACTERISTICS,ANDAFTERCOMPARINGWITHTHEEXPERIMENTALRESULTSTODETERMINETHEMODELPARAMETERSANDGRIDNUMBERITSTUDIESTHEAIRFLOWDISTRIBUTIONANDRESISTANCECHARACTERISTICSINTHECONDITIONSOFDIFFERENTTOWERSHAPES,ANDANALYSISTOSUMMARIZETHECOOLINGTOWERRESISTANCECALCULATIVEFORMULAANDTHERELATIONSHIPBETWEENTOWERSHAPEANDAIRFLOWDISTRIBUTIONUNIFORMITYTHEDIFFERENCEOFCOMPUTATIONALRESISTANCECOEFFICIENTANDTHEEXPERIMENTALRESULTSISLESSTHAN5,ITCANPROVIDEAREFERENCEFORDESIGN2数学模型及计算方法21空气流场控制方程塔内外流场为等温、不可压流动，其控制方程包括连续方程、动量方程，并选用双方程K湍流模式对方程进行封闭，各方程可写为统一形式SVT（1）式中为空气密度，KG/M3；为空气流速，M/S。各控制方程的变量、扩散系数项与源项如下表1。S表1控制方程中各变量代表参数控制方程S连续方程100动量方程（流速），UVWTIXP湍能方程KKKT/GK耗散方程/TC21其中生成项；为空气分子粘性系数；为压力；为紊流粘性JIIJJITXUXGKPT系数，由动能和紊动耗散率求出，为经验常数；和分别为和的2KCTKK紊流普朗特数。2MATHEMATICALMODELSANDCALCULATIVEMETHODS21AIRFLOWGOVERNINGEQUATIONSTHETOWERFLOWFIELDISISOTHERMALANDINCOMPRESSIBLEITSGOVERNINGEQUATIONSINCLUDECONTINUITYEQUATION,MOMENTUMEQUATION,WHICHCANBECLOSEDWITHTWOEQUATIONKTURBULENCEMODEL,THESEEQUATIONSCANBEWRITTENASAUNIFIEDFORM1SVTWHEREISAIRDENSITY,KG/M3ISAIRVELOCITY,M/SALLGOVERNINGEQUATIONSVARIABLE、DIFFUSIONCOEFFICIENTTERMANDSOURCETERMARESHOWNASTABLE1BELOWSTABLE1,ANDOFEVERYGOVERNINGEQUATIONGOVERNINGEQUATIONSSCONTINUITYEQUATION100MOMENTUMEQUATION（VELOCITYOF，UVWTIXPFLOW）TURBULENTENERGYEQUATIONKKKT/GKDISSIPATIONEQUATION/TCK21GENERATEDITEM,ISVISCOSITYCOEFFICIENTOFTHEAIRMOLECULESJIIJJITXUXGKISPRESSURE,PAISTHETURBULENTVISCOSITYCOEFFICIENT,WHICHISCANBECALCULATEDBYTHEPTTURBULENTKINETICENERGYANDDISSIPATIONRATE,ISANEMPIRICALCONSTANTK2KCTANDARETURBULENTPRANDTLNUMBEROFANDKK22边界条件底部为固壁无滑移边界条件，四周及顶部采用压力出口边界条件，塔壳采用固壁边界条件。进风口及塔的出口都设置成内部边界；填料区域设置成多孔介质边界条件，并根据实测填料阻力系数设置各方向阻力系数；风机采用FLUENT风扇边界条件，也可采用第一类边界条件。22BOUNDARYCONDITIONSTHEBOTTOMOFTHECOMPUTATIONALDOMAINISSOLIDWALLBOUNDARYCONDITIONWITHNOSLIP,ALLAROUNDANDTOPISPRESSUREOUTLETBOUNDARYCONDITIONS,THETOWERSHELLISSOLIDWALLBOUNDARYCONDITIONTHEBOUNDARIESOFTHEAIRINLETANDOUTLETAREDEFINEDASINTERIORTHEPOROUSMODELISUSEDTOSIMULATETHEFILLANDACCORDINGTOTHEMEASUREDRESISTANCECOEFFICIENTTOSETTHEFILLRESISTANCECOEFFICIENTINEACHDIRECTIONTHEFLUENTFANMODELISUSEDTOSIMULATETHEFANOFTHETOWER,FIRSTBOUNDARYCONDITIONCANALSOBEUSED23冷却塔阻力系数及风速分布均匀性计算鼓风式机械通风冷却塔，气流经由风机鼓入塔内，依次经过塔进风口，雨区、填料等，并经由出口排入到大气中，气流经过各部分的阻力为该区域前后断面的全压差，一般表示为阻力系数与填料断面平均气流速度头之积2FVP（2）式中为气流经过某区域前后断面的全压差（PA）；为空气密度（KG/M3）；为填料断面PFV平均风速（M/S）。填料断面处风速分布状况影响冷却塔的热力特性，一般将填料断面风速分布均匀性作为一个设计指标，用风速分布均布系数表示NVFI21/（3）式中为填料断面风速分布均布系数；为填料断面各点风速（M/S）；N为风速统计点的个数。I23COMPUTATIONALMETHODSOFTHECOOLINGTOWERRESISTANCECOEFFICIENTANDWINDVELOCITYUNIFORMITYFORTHEFORCEDDRAFTMECHANICALCOOLINGTOWER,AIRFLOWISBLOWNINTOTHETOWERBYTHEFAN,SEQUENTIALLYTHROUGHTHETOWERINLET,RAINZONE,FILLETC,ANDISDISCHARGEDINTOTHEATMOSPHERETHROUGHTHEOUTLETFINALLYTHERESISTANCEOFEACHPARTISTHEPRESSURELOSSOFTHEREGION,WHICHISGENERALLYEXPRESSEDASTHERESISTANCECOEFFICIENTMULTIPLYTHEAVERAGEFLOWVELOCITYHEAD22FVPWHEREISTHEPRESSURELOSSOFTHEREGION（PA）ISAIRDENSITY（KG/M3）ISPFVTHEAVERAGEWINDVELOCITYOFTHEFILLSECTION（M/S）DISTRIBUTIONOFWINDVELOCITYATTHEFILLSECTIONAFFECTSTHETHERMODYNAMICCHARACTERISTICSOFTHECOOLINGTOWER,GENERALLYPUTTHEWINDVELOCITYDISTRIBUTIONUNIFORMITYOFTHEFILLSECTIONASADESIGNINDEX,ITCANBEEXPRESSEDWITHAVELOCITYDISTRIBUTIONUNIFORMITYCOEFFICIENTNVFI21/（3）WHEREISTHEVELOCITYDISTRIBUTIONUNIFORMITYCOEFFICIENTISTHEVELOCITYATTHEIVMEASUREPOINTINTHEFILLSECTION（M/S）NISTHEVELOCITYSTATISTICALPOINTSNUMBER24模型的验证对已具有试验结果的某抽风式机械通风冷却塔的空气动力特性模型试验6作对比验证计算，冷却塔如图1示，首先对冷却塔进行网格的敏感性分析，然后再将计算结果进行对比分析。风机进口过渡段风机收水器填料配水装置填料支撑结构图1抽风式机械通风冷却塔模型试验布置示意图不同填料阻力条件下模型试验实测与计算结果对比如图2所示，图中横坐标L0/L为距其中一侧塔壁的相对距离，V/ERROR为相对风速，V为测点风速，为测点风速的平均值。进风口气流VXV流态作对比如图3所示，从图中可以看出，试验结果与数值计算结果规律较为一致，吻合良好。060708091011121314000204060810V/VL0/L试验结果填料阻力系数10计算结果填料阻力系数10试验结果填料阻力系数20计算结果填料阻力系数20试验结果填料阻力系数30计算结果填料阻力系数30图2试验与计算填料断面风速分布对比（A）模型试验结果（B）数值计算结果图3试验与计算进风口上沿气流流态分布对比进风口区域冷却塔阻力系数试验与计算结果对比见表2，二者相差不大于5，吻合较好。表2模型试验与数值计算进风口区域阻力系数对比结果进风口区域阻力系数填料阻力系数试验结果计算结果相差10161161000202612734323036138049224MODELVALIDATIONTODOVALIDATIONWITHTHEEXPERIMENTALRESULTSOFAERODYNAMICCHARACTERISTICSOFANINDUCEDDRAFTMECHANICALCOOLINGTOWERMODEL,THELAYOUTDRAWINGOFTHECOOLINGTOWERISSHOWNASFIGURE1,FIRSTLY,ANALYSISTHEGRIDSENSITIVITY,THENCOMPAREANDANALYZETHERESULTSFLIERSUPORTSCTUREWATERDISTBUIONSYTEMFILERDRIFTELMINATORFANFANILETRASITONECTIFIG1LAYOUTDRAWINGOFTHEINDUCEDDRAFTMECHANICALCOOLINGTOWERMODELINTHECONDITIONSOFDIFFERENTFILLRESISTANCECOEFFICIENTS,THERESULTSOFTHECOMPARISONBETWEENEXPERIMENTALANDCOMPUTATIONALARESHOWNINFIGURE2,ABSCISSAL0/LISTHERELATIVEDISTANCEFROMONESIDETOTHEWALL,V/ISRELATIVEWINDVELOCITY,VISTHEVELOCITYATTHEVMEASUREPOINT,ISTHEAVERAGEMEASUREPOINTSWINDVELOCITYTHERESULTSOFTHECOMPARISONVBETWEENEXPERIMENTALANDNUMERICALINLETAIRFLOWSTATEARESHOWNINFIGURE3,ASCANBESEENFROMFIG3,EXPERIMENTALRESULTSISCONSISTENTWITHTHERESULTSOFNUMERICALCALCULATIONFIG2COMPARISONBETWEENEXPERIMENTALANDCOMPUTATIONALFILLSECTIONWINDVELOCITYDISTRIBUTION（A）EXPERIMENTALRESULTS（B）NUMERICALRESULTSFIG3COMPARISONBETWEENEXPERIMENTALANDNUMERICALINLETAIRFLOWDISTRIBUTIONCOMPARISONBETWEENEXPERIMENTALANDNUMERICALCOOLINGTOWERAIRINLETAREARESISTANCECOEFFICIENTARESHOWNINTABLE2，THEDIFFERENCEISNOTGREATERTHAN5，THERESULTSTALLYWELLTABLE2COMPARISONBETWEENEXPERIMENTALANDCOMPUTATIONALCOOLINGTOWERAIRINLETAREARESISTANCECOEFFICIENTINLETRESISTANCECOEFFICIENTFILLRESISTANCECOEFFICIENTEXPERIMENTALRESULTSNUMERICALRESULTSDIFFERENCE1016116100020261273432303613804923计算结果及分析鼓风式机械通风冷却塔不同的塔型尺寸，如填料的安装高度、塔出口收缩段的高度、角度等，都会影响塔内气流阻力特性及风速分布，本文分别研究了不同塔型对冷却塔气流特性的影响。鼓风式机械通风冷却塔立面布置如图4所示，塔的平面尺寸为90M90M，风机直径为60M。图4鼓风式机械通风冷却塔立面布置图3RESULTSANDANALYSISDIFFERENTTOWERSHAPESFORTHEFORCEDDRAFTMECHANICALCOOLINGTOWER,SUCHASINSTALLATIONHEIGHTOFTHEFILL、THECONVERGENTSECTIONHEIGHTANDANGLE,WILLAFFECTTHETOWERAIRFLOWRESISTANCECHARACTERISTICSANDWINDVELOCITYDISTRIBUTIONTHISPAPERSTUDIESTHEINFLUENCEOFDIFFERENTTOWERSHAPESONTHEAIRFLOWCHARACTERISTICSTHEFORCEDDRAFTMECHANICALCOOLINGTOWERELEVATIONISSHOWNASFIG4,TOWERPLANESIZEIS90M90M,FANDIAMETERIS60MLHCFAIRNLETFANILERWATERDISTBUIONSYTEMWATERCOLTINDEVICAIROUTLEFIG4THEFORCEDDRAFTMECHANICALCOOLINGTOWERELEVATION31计算模型的建立及网格划分流体仿真计算域范围的选取影响计算的速度和精度，根据经验，当计算域到达一定的大小时，塔内的流场就不再受计算域大小的限制。假定塔高为H，宽为W，进风口高为H1，经过试算分析，计算域进风口上下游宽度取为3H1、宽度取为4W、高度取为2H时再增大计算域范围对计算影响不HCHF大。数值模拟计算与计算网格的划分密切相关，本文进行了网格相关性分析计算，结果如图56所示。当网格数量达到50万时，塔内气流特性受网格数量的影响已经很小，计算区域网格图如图7所示。570572574576578580582584102030405060708090冷却塔总阻力系数网格数量（万）图5网格数量对冷却塔阻力系数影响01234567891012030405060708090填料断面风速分布均布系数（）网格数量（万）图6网格数量对填料断面风速分布影响图7塔内及计算域网格示意图31ESTABLISHMENTOFCALCULATIVEMODELANDMESHGENERATIONTHESCALEOFFLUIDCOMPUTATIONALDOMAINAFFECTSTHECALCULATIVEVELOCITYANDACCURACY,BASEDONEXPERIENCE,WHENCOMPUTATIONALDOMAINREACHESTOACERTAINSCALE,FLOWFIELDINTHETOWERISNOLONGERLIMITEDBYCOMPUTATIONALDOMAINSCALEASSUMETHATTHETOWERHEIGHTISH,WIDTHISW,AIRINLETHEIGHTISH1,ACCORDINGTOTHERESULTSOFTHETRIALCOMPUTATION,ITMAKESLITTLEDIFFERENCETOINCREASETHECOMPUTATIONALDOMAINWHENTHELENGTHOFUPSTREAMANDDOWNSTREAMOFAIRINLETIS3H1,THEWIDTHOFTHEWHOLECOMPUTATIONALDOMAINIS4WANDTHEHEIGHTIS2HNUMERICALSIMULATIONISCLOSELYRELATEDTOGRIDPARTITION,THISPAPERANALYSISGRIDCORRELATION,THERESULTSARESHOWNINFIGURE5AND6ITISKNOWNACCORDINGTOTHETWOFIGURESTHATTHEGRIDNUMBERHASLITTLEEFFECTONAIRFLOWCHARACTERISTICSINTHETOWERWHENTHEGRIDNUMBERREACHING500000,COMPUTATIONALDOMAINGRIDISSHOWNASFIG75705725745765785805825841030507090COLINGTOWERTOTALRESITANCEOEFICENTGRIDNUMBER（1104）FIG5THEINFLUENCEOFGRIDNUMBERONTHECOOLINGTOWERRESISTANCECOEFFICIENT012345678910102030405060708090FILERSCTIONWINDSPEDISTRIBUTIONUIFORMITY（）GRIDNUMBER（104）FIG6THEINFLUENCEOFGRIDNUMBERONTHEFILLSECTIONVELOCITYDISTRIBUTIONFIG7THETOWERANDCOMPUTATIONALDOMAINGRIDSCHEMATICDIAGRAM32填料安装高度对冷却塔气流特性影响不同的淋水填料安装高度时，冷却塔的阻力系数与填料断面风速分布计算结果如图8和图9所示，图中横坐标HF/L为填料底至进风口上沿距离与塔宽之比，结果表明，填料安装高度对整塔阻力系数影响不大，但填料安装高度离塔进风口远时，填料阻力较小者风速分布均匀性变差。4505050606507075080010203冷却塔总阻力系数HF/L填料阻力系数15填料阻力系数30填料阻力系数45图8填料安装高度对整塔阻力系数的影响3456789100010203填料断面风速分布均布系数（）HF/L填料阻力系数15填料阻力系数30填料阻力系数45图9填料安装高度对填料断面风速分布均匀性的影响32THEINFLUENCEOFTHEFILLINSTALLATIONHEIGHTONTHECOOLINGTOWERAERODYNAMICCHARACTERISTICSINTHECONDITIONSOFDIFFERENTFILLINSTALLATIONHEIGHT,THECOMPUTATIONALRESULTSOFCOOLINGTOWERRESISTANCECOEFFICIENTANDFILLSECTIONWINDVELOCITYDISTRIBUTIONARESHOWNINFIGURE8ANDFIGURE9,ABSCISSAHF/LISTHEDISTANCEFROMFILLBOTTOMTOTOPOFTHEAIRINLETDIVIDESTOWERWIDTH,ITTURNSOUTTHATTHEBOTTOMHEIGHTOFTHEFILLHASLITTLEEFFECTONTHEWHOLETOWERRESISTANCECOEFFICIENT,BUTWHENFILLINSTALLATIONHEIGHTISHIGHER,THESMALLERTHEFILLRESISTANCECOEFFICIENTIS,THEWORSETHEWINDVELOCITYDISTRIBUTIONUNIFORMITYIS450505060650707508005010150202503COLINGTOWERTOALRESITANCEOEFICENTHF/LFILERESITANCEOEFICENTIS15FILERESITANCEOEFICENTIS30FILERESITANCEOEFICENTIS45FIG8THEINFLUENCEOFFILLINSTALLATIONHEIGHTONTHECOOLINGTOWERRESISTANCECOEFFICIENT345678910005010150202503FILERSCTIONWINDSPEDISTRIBUTIONUIFORMITY（）HF/LFILERESITANCEOEFICENTIS15FILERESITANCEOEFICENTIS30FILERESITANCEOEFICENTIS45FIG9THEINFLUENCEOFFILLINSTALLATIONHEIGHTONTHEFILLSECTIONVELOCITYDISTRIBUTION33冷却塔出口收缩高度对冷却塔气流特性的影响调整冷却塔出口收缩高度，冷却塔的阻力系数与填料断面风速分布计算结果如图10和11所示，图中横坐标HC/L为收缩段至进风口上沿距离与塔宽之比。由图可以看出，随着塔出口收缩高度的增加，冷却塔阻力系数降低，当HC/L达到075后，阻力系数变化减小，大于090后基本不再变化，填料断面风速分布均布系数亦有相似的规律。40506070809005006007008009010冷却塔总阻力系数HC/L填料阻力系数15填料阻力系数30填料阻力系数45图10收缩高度对整塔阻力系数的影响4567891011205060708091填料断面风速分布均布系数（）HC/L填料阻力系数15填料阻力系数30填料阻力系数45图11收缩高度对填料断面风速分布均匀性的影响33THEINFLUENCEOFTHEOUTLETCONVERGENTSECTIONHEIGHTONTHECOOLINGTOWERAERODYNAMICCHARACTERISTICSADJUSTINGTHECOOLINGTOWEROUTLETCONVERGENTHEIGHT,THECOMPUTATIONALRESULTSOFCOOLINGTOWERRESISTANCECOEFFICIENTANDFILLSECTIONWINDVELOCITYDISTRIBUTIONARESHOWNINFIGURE10ANDFIGURE11,ABSCISSAHC/LISTHEDISTANCEFROMTHECONVERGENTSECTIONTOTHETOPOFTHEAIRINLETDIVIDESTOWERWIDTHASCANBESEENFROMTHETWOFIGURES,WITHTHEINCREASEOFTHETOWEROUTLETCONVERGENTHEIGHT,THEWHOLECOOLINGTOWERRESISTANCECOEFFICIENTDECREASE,WHENHC/LREACHES075,THERESISTANCECOEFFICIENTCHANGEBECOMESSLOWLY,WHENHC/LISGREATERTHAN090,ITSNOCHANGE,FILLSECTIONWINDVELOCITYDISTRIBUTIONUNIFORMITYCOEFFICIENTALSOHASTHESIMILARLAWS405060708090500607080910COLINGTOWERTOALRESITANCEOEFICENTHC/LFILERESITANCEOEFICENTIS15FILERESITANCEOEFICENTIS30FILERESITANCEOEFICENTIS45FIG10THEINFLUENCEOFCONVERGENTHEIGHTONTHECOOLINGTOWERRESISTANCECOEFFICIENT4567891011205060708091FILERSCTIONWINDSPEDISTRIBUTIONUIFORMITY（）HC/LFILERESITANCEOEFICENTIS15FILERESITANCEOEFICENTIS30FILERESITANCEOEFICENTIS45FIG11THEINFLUENCEOFCONVERGENTHEIGHTONTHEFILLSECTIONWINDVELOCITYDISTRIBUTION34冷却塔出口收缩角度对冷却塔气流特性的影响调整冷却塔出口收缩角度，冷却塔的阻力系数与填料断面风速分布计算结果如图12和13所示,图中横坐标为收缩段与水平的夹角。随着塔出口收缩角度的增加，冷却塔阻力系数降低，但趋势不明显。填料断面风速分布均布系数基本不受塔出口收缩角度的影响。202503035040450505060152025303540冷却塔总阻力系数收缩段与水平的夹角（）填料阻力系数15填料阻力系数30填料阻力系数45图12收缩角度对整塔阻力系数的影响024681012141924293439填料断面风速分布均布系数（）收缩段与水平夹角（）填料阻力系数15填料阻力系数30填料阻力系数45图13收缩角度对填料断面风速分布均匀性的影响34THEINFLUENCEOFCONVERGENTANGLEONTHECOOLINGTOWERAIRFLOWCHARACTERISTICSADJUSTINGTHECOOLINGTOWEROUTLETCONVERGENTANGLE,THECOMPUTATIONALRESULTSOFCOOLINGTOWERRESISTANCECOEFFICIENTANDFILLSECTIONWINDVELOCITYDISTRIBUTIONARESHOWNINFIGURE12ANDFIGURE13,ABSCISSAISTHEANGLEBETWEENCONVERGENTSECTIONANDHORIZONWITHTHEINCREASEOFTOWEROUTLETCONVERGENTANGLE,THECOOLINGTOWERRESISTANCECOEFFICIENTDECREASE,BUTTHISTRENDISNOTOBVIOUSFILLSECTIONWINDVELOCITYDISTRIBUTIONUNIFORMITYCOEFFICIENTISNOTAFFECTEDBYTOWEROUTLETCONVERGENTANGLE2025030350404505050601924293439COLINGTOWERTOALRESITANCEOEFICENTA（）FILERESITANCEOEFICENTIS15FILERESITANCEOEFICENTIS30FILERESITANCEOEFICENTIS45FIG12THEINFLUENCEOFCONVERGENTANGLEONTHECOOLINGTOWERRESISTANCECOEFFICIENT024681012141924293439FILERSECTIONWINDSPEDISTRIBUTIONUIFORMITY（）A（）FILERESITANCECOEFICENTIS15FILERESITANCECOEFICENTIS30FILERESITANCECOEFICENTIS45FIG13THEINFLUENCEOFCONVERGENTANGLEONTHEFILLSECTIONWINDVELOCITYDISTRIBUTION35冷却塔阻力系数计算公式按式（2）对不同塔型尺寸的计算结果进行分析总结，可获得以下冷却塔自风机进口到塔出口相对于填料断面速度头的阻力系数计算公式。公式整理时塔的出口段收缩角为27，收缩段相对高度为05092。（4）2001284032789430FLHFFFFF（式中为填料阻力系数；为冷却塔淋水面积（）；为冷却塔出口面积（）。FF35CALCULATIVEFORMULAOFCOOLINGTOWERRESISTANCECOEFFICIENTINTHECONDITIONOFSUMMARIZINGTHERESULTSOFDIFFERENTTOWERSHAPESACCORDINGTOEQUATION2,ITCANOBTAINTHECOOLINGTOWERRESISTANCECOEFFICIENTCALCULATIVEFORMULAWHICHISFROMTOWERINLETTOOUTLETRELATIVETOTHEFILLSECTIONWINDVELOCITYTHECONVERGENTANGLEIS27,THECONVERGENTSECTIONRELATIVEHEIGHTHC/LIS05092WHENFINISHINGTHEFORMULA42001284032789430FLHFFFFF（WHEREISTHEFILLRESISTANCECOEFFICIENTISTOWERSRAINAREAM2ISOUTLETAREAFF0M2。4结论本文对鼓风式机械冷却塔在不同填料安装高度、不同收缩高度与角度等条件下的塔的空气动力特性进行了数值模拟，结果表明，填料安装高度对冷却塔整塔阻力系数影响不大，在填料阻力小时，安装高度高时均匀性变差；出口收缩段相对高度越大，阻力越低，填料断面风速分布也越均匀，当其大于090时所获的收益已经很小；出口收缩段与水平夹角增大时，冷却塔阻力系数降低，但趋势不明显，填料断面风速分布均布系数基本不受塔出口收缩角度的影响。本文还分析总结了鼓风式冷却塔的阻力系数计算公式，计算方法经过类似模型试验对比，与试验结果偏差在5之内，可供冷却塔设计计算参考。4CONCLUSIONSTHISPAPERESTABLISHESANUMERICALMODELTOSTUDYTHEAERODYNAMICCHARACTERISTICSOFTHEFORCEDDRAFTMECHANICALCOOLINGTOWERINTHECONDITIONSOFDIFFERENTFILLINSTALLATIONHEIGHTS、DIFFERENTCONVERGENTHEIGHTSANDANGLES,ITTURNSOUTTHATTHEBOTTOMHEIGHTOFTHEFILLHASLITTLEEFFECTSONTHEWHOLETOWERRESISTANCECOEFFICIENT,BUTWHENFILLINSTALLATIONHEIGHTISHIGHER,THESMALLERT