平流二次沉淀池中温差对异重流影响的数值模拟

收稿日期:2012-11-15基金项目:陕西省重点学科建设专项资金资助项目。作者简介:谭立新，女，博士，副教授，研究方向为计算水力学及两相流数值模拟。E-mail:tanlx@xaut．edu．cn。文章编号:1006-4710(2013)02-0182-06平流二次沉淀池中温差对异重流影响的数值模拟谭立新1，李博2，李尔康1(1．西安理工大学水利水电学院，陕西西安710048;2．北方重工设计研究院散料成套工程技术研究所，辽宁沈阳110141)摘要:由于进水与池内水的浓度差异及不同季节进水与池内水的温度差异，会在沉淀池内产生异重流现象，会对池内的流态产生影响。以城市污水处理厂中平流二次沉淀池为研究对象，针对池内的异重流现象应用数值模拟的方法，选取ＲNGk-ε双方程模型和两相流混合模型作为计算的数学模型，对平流式二沉池池内单纯由浓度差引起的异重流，进一步引入温度差，进行了流动的二维数值模拟。研究了温差对平流二沉池中异重流的影响。结果表明，温差产生的影响随温差类型及温差大小的不同而改变，低温水流入产生下异重流效应，高温水流入产生上异重流效应;温差越大，影响越明显;随着温度达到平衡，温差的影响渐趋消失。关键词:平流二次沉淀池;数值模拟;异重流中图分类号:X703文献标志码:ANumericalSimulationoftheEffectofTemperatureDifferenceonGravityFlowinＲectangularSecondarySettingTanksTANLixin1，LIBo2，LIErkang1(1．FacultyofWaterＲesourcesandHydroelectricEngineering，Xi’anUniversityofTechnology，Xi’an710048，China;2．ＲesearchDepartmentofEPCEngineeringTechnologyofNHIDesignandＲesearchInstitute，Shenyang110141，China)Abstract:Theconcentrationdifferencebetweeninfluentwaterandtanks’water，orthedifferentinlettemperatureindifferentseasonswouldproducegravityflowphenomenainthesedimentationtanks．Inthispaper，gravityfloweffectedbytemperaturedifferenceinrectangularsecondarysettlingtanksisstudiedbynumericalsimulation．Inaspectofmathematicalmodel，theＲNGk-εtwo-equationturbulencemodelandtheMixturemodelareselectedasthesimulationsecondarysettingtankmathematicalmodel，andthetem-peraturedifferencesarefurtherintroducedintothedensityflowcausedbythesimpleconcentrationdiffer-encesintherectangularsecondarysettingtankstocarryouttheflowingZ-Dnumericalsimulation．Theeffectoftemperaturedifferencesuponthedensityflowintherectangularsecondarysettingtanksisstudied．Theresultsshowthattheeffectsoftemperaturedifferencechangeswiththetypesandsizeofthetemper-aturedifference，andthatlow-temperatureinflowwouldproducethegravityflowinthesubstrate，whilehigh-temperatureinflowproducesthegravityflowonthetop．Accordingly，thegreateristhetemperaturedifference，themoreobvioustheinfluencewillbe，andtheeffectoftemperaturedifferencewillgraduallydisappearwiththetemperaturereachingbalance．