瞬变流课程论文_中英翻译

EquivalentPipeAlgorithmforMetalSpiralCasingandItsApplicationinHydraulicTransientComputationBasedonEquiangularSpiralModel论文翻译摘自《JournalofHydrodynamics》专业：水工结构工程姓名：喻江学号：150202020013授课老师：张健俞晓东河海大学水利水电学院2016年1月5日JournalofHydrodynamics论文翻译1英文题目：EquivalentPipeAlgorithmforMetalSpiralCasingandItsApplicationinHydraulicTransientComputationBasedonEquiangularSpiralModel中文题目：基于等角螺旋模型的金属蜗壳等效管径算法及其在水力瞬变流计算中的运用Abstract:摘要：Forthemetalspiralcasingofwaterturbines,anewequivalentpipealgorithmisdevelopedbasedontheideaofequiangularspiral.Prototypetestsandcomputationsarecarriedouttoinvestigatethehydraulictransientcharacteristics.Thecomputationresultsbyusingthenewmodelareinagoodagreementwiththeprototypetestdatawithrespecttothemaximumspeedoftheturbine-generatorunit,themaximumwaterhammerpressureinthespiralcasingandthemaximumvacuuminthedrafttube.Theproposedmethodisasignificantimprovementovertheconventionalalgorithmwiththeaccuracyincreasedandtheerrorreducedbyabout3%.基于等角螺旋模型，针对水轮机中的金属蜗壳提出了一种新型等效管径算法。为了研究其水力瞬变流特性，开展了模型试验和算法分析。通过数值分析与模型试验，对水轮机发电机组的最大流速、金属蜗壳中的最大水锤压力、导流管中最大真空度进行对比分析，其结果吻合良好。本文提出的研究方法相较于传统算法得到了更大改进，具有更高的精度，其误差减小到了3%。Keywords:关键词：equiangularspiral,metalspiralcasing,equivalentpipe,hydraulictransient等角螺旋，金属蜗壳，等效管径，水力瞬变流Introduction：引言：Hydraulictransitionprocessesarecommonflowphenomenainhydropowerstations,pumpingstationsandwatersupplypipenetworks.Disastrousaccidentsmighthappenduringhydraulictransitionprocesses.Thehydraulictransitionprocessesinhydropowerstations,pumpingstationsandwatersupplypipe水力瞬变流过程在水电站、泵站，以及供水管网中，是一种常见的流体现象。在水力瞬变流过程中安全事故时有发生。通过水力瞬变流理论分析、模型试验、工程运用，已经对水电站、泵站和供水管网中的水力瞬变流过程JournalofHydrodynamics论文翻译~2~networkswerestudiedbasedonthehydraulictransientflowtheoryanalysis,thenumericalsimulations,themodelexperiment,aswellasengineeringapplications.Inthehydraulictransientcomputationforhydropowerstations,thedischargeandtorquecharacteristicsdiagramsoftheturbineweredeterminedbythemodelefficiencyhilldiagramandtherunawayspeedcharacteristicsdiagraminsteadyworkingconditions.Thesecharacteristicsdiagramsdonotincludetheimpactofthewaterinertiainthemetalspiralcasingunderunstableworkingconditions.Itwouldbedifficulttoaccuratelysimulatethehydraulictransientcharacteristicsofthemetalspiralcasing,owingtoitsvariablecrosssection.Ingeneral,themetalspiralcasingisshortinlength,sothewaterinertiaisrelativelysmallascomparedwiththewaterinertiainthediversionandpowersystem.Therefore,thewaterinertiainthemetalspiralcasingisgenerallyignoredinordertosimplifythehydraulictransientnumericalcomputationandtheaccuracyofthenumericalcomputationmaybereducedaccordingly.However,thewaterinertiainthediversionandpowersystemisaveryimportantfactoraffectingthedynamiccharacteristicsoftheregulatingsystem.Duetothecomplexityofthemetalspiralcasing,itisnoteasytoconsideradequatelythewaterinertiainthehydraulictransientnumericalcomputation,andthisproblem进行了研究。对于水电站中水力瞬变流计算，在稳定运行时，涡轮的出流和力矩特性由模型效率和飞逸转速特性共同决定。然而，这些特征图并不能表征在不稳定运行时金属蜗壳中水体惯性带来的影响。由于金属蜗壳为变截面结构，因此，将很难准确模拟金属蜗壳的水力瞬态特征。通常情况下，金属蜗壳在长度方向很短，与引水系统和发电系统中的水体惯性相比，金属蜗壳中的水体惯性较小。因此，为了简化金属蜗壳中水力瞬变流数值计算以及计算精度，金属蜗壳中的水体惯性被忽略。然而，引水系统和发电系统中水体惯性是一个重要因数，将影响到调节系统的动力特性。由于金属蜗壳的复杂性，在水力瞬变流计算中很难准确考虑水体惯性的影响。尤其是当考虑到水力瞬变流特性时，这个问题必须得到重视。JournalofHydrodynamics论文翻译~3~mustbeaddressedespeciallywhenthehydraulictransientcharacteristicsareconcerned.Thecharacteristicsofthespiralcasingwerestudiedandtheconceptoftheequivalentpipeofthespiralcasingwasproposedtodealwiththewaterinertiainthehydraulictransientnumericalcomputation.Asimpleandpracticalequivalentpipealgorithmwasdeduced,thecorrectnessofwhichissubjecttodoubt.Inthisstudy,withdueconsiderationoftheflowsinthemetalspiralcasingofthewaterturbine,thespiralcasingequationisderivedandanequivalentpipealgorithmisdevelopedbasedontheequiangularspiralidea.Numericalcomputationsandprototypetestsarecarriedouttoinvestigatethehydraulictransientcharacteristics.Somesuggestionsaremadetodealwiththemetalspiralcasinginhydraulictransientnumericalcomputationsforhydropowerstations.为了解决水力瞬变流数值计算中水体惯性问题，研究了蜗壳特征，等效管径概念被考虑进来。由此推导出了一种简单、实用的等效管算法，而这种算法的正确性有待考究。在本研究中，考虑水轮机中金属蜗壳的流变特征，基于等角螺旋模型，针对水轮机中的金属蜗壳提出了等效管径算法并得到了相关方程。通过数值分析和模型试验，研究了其水力瞬变特性。为了解决水电站中金属蜗壳水力瞬变流数值计算问题，文中还提出了一些有效建议。