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1、温排水数学模型温度场影响因子的探讨1211郑国栋顾立忠黄东徐林春(1.广东省水利水电科学研究院广州510610;2.华北水利水电学院郑州450011)摘要:本文根据MIKE21在温排水数值模拟领域的应用,分析了MIKE21平面二维热对流扩散模型,提出在受潮汐影响的感潮河道中扩散系数,散热系数和新增流量是影响温度场的三个重要影响因子。比较模型中热扩散系数和散热系数选取和计算方法可以得出:扩散系数的大小取决于模型计算的网格尺度、时间步长和流速,而影响散热系数的主要是水温和风速。对于枯水期的固定潮型(径流量比例很小),散
2、热系数一定时,温度场在水体中以热源(排水口)为中心向四周扩散,且扩散系数越大,温水扩散速度越快,同时,在纵向上,受水流挟带的作用,热水带随潮涨落在排水口上下游来回摆动;当扩散系数一定时,散热系数越大,温度耗散的速度越快,温升范围也越大,水流间能量交换的能力也越强,同一点的温升值就越小。当扩散系数和散热系数一定,对于丰水期的固定潮型(径流量比例较大),温度场的范围有明显的缩小,这说明温度场的范围也受上游来流流量的影响。最后,应用模型在实际工程中的进行了验证计算。关键词:温排水模型,对流扩散模型,扩散系数,散热系数,新
3、增流量DiscussionOnTheFactorsofTemperatureFieldInfluencesInThermalDischargeModel1211GuodongZhengLizhongGuDongHuangLinchunXu1.GuangdongResearchInstituteofWaterResourcesandHydropower,Guangzhou,5106102.NorthChinaUniversityofWaterConservancyandElectricPower,Zhengzhou,
4、450011Abstract:AccordingapplicationofMIKE21onthermaldischargenumericalsimulationofpowerplant,theMIKE212-dadvection-dispersionflowmodelisanalyzedinthispaper.Theideathatdispersioncoefficients,heatdissipationcoefficientandadditionaldischargearethreeimportantfacto
5、rsoftemperaturefieldinfluencesintidereachisadvanced.Comparingwiththecomputationmethodsofthedispersioncoefficientsandheatdissipationcoefficient,itisfoundthatthedispersioncoefficientsdependonthedimensionofthegrids,timestepandvelocity,whiletheheatdissipationcoeff
6、icientmainlydependsonwatertemperatureandvelocityofwind.Forfixedtidetypeindryseason,whentheheatdissipationcoefficientisconstant,thetemperaturefieldisdissipatedaroundtheheatsource.Thegreaterthedispersioncoefficientsare,thefasterthedissipatedvelocityis.Simultaneo
7、usly,onordinatedirection,becauseofthewaterflow,warmwaterisswungaroundtheheatsourceasthetiderisingandfalling;whenthedispersioncoefficientsareconstant,thegreaterthedissipationcoefficientis,thefastthedissipatedvelocityoftemperaturewillbestronger.Therefore,thetemp
8、eraturerisingscopewillgetbigger,theenergyexchangingbetweencoolandwarmwaterwillbestronger,andalsothevalueoftemperaturerisinginthesamespotisgettingsmaller.Whendispersioncoefficientsa