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ID:21681632
大小:1.21 MB
页数:9页
时间:2018-10-23
《流体力学与传热习题参考解答英文》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、1.Waterispumpedataconstantvelocity1m/sfromlargereservoirrestingonthefloortotheopentopofanabsorptiontower.Thepointofdischargeis4meterabovethefloor,andthefrictionlossesfromthereservoirtothetoweramountto30J/kg.Atwhatheightinthereservoirmustthewaterlevelbekeptifthepumpcandeveloponly60
2、J/kg?U1=0W=60j/kg2.Thefluid(density1200kg/m3)ispumpedataconstantrate20m3/hfromthelargereservoirtotheevaporator.Thepressureabovethereservoirmaintainsatmospherepressureandthepressureoftheevaporatorkeeps200mmHg(vacuum).Thedistancebetweenthelevelofliquidinthereservoirandtheexitofevapo
3、ratoris15meterandfrictionallossinthepipeis120J/kgnotincludingtheexitofevaporator,whatisthepumpeffectiveworkandpowerifthediameterofpipeis60mm?3.Watercomesoutofthepipe(Φ108x4mm),asshowninFig.Thefrictionlossofthepipelinewhichdoesnotcoverthelossattheexitofpipecanbecalculatedbythefollo
4、wingequation:hf=6.5U2whereUisthevelocityinthepipe,finda.watervelocityatsectionA-A'.b.waterflowrate,inm3/h.4.Waterpassesthroughthevariablepipe.Thevelocityinthesmallpipeis2.5m/s.TheverticalglasstubesareinsertedrespectivelyatthesectionAandBtomeasurethepressure(seefig.)Ifthefrictionlo
5、ssbetweentwosectionis15J/kg,whatisthewatercolumndifferencebetweentwoglasstubes?Bytheway,drawtherelativeliquidcolumnheightoftwotubesintheFig.5.Acentrifugalpumptakesbrine(density1180kg/m3,viscosity1.2cp)fromthebottomofasupplytankanddeliversitintoanothertank.Thelinebetweenthetanksis3
6、00mof25mmdiameterpipe(innerdiameter).Theflowrateis2m3/h.Inthisline,therearetwogatevalves,fourelbows(90o)andonereturnbend,whatisthefrictionlossiftheroughnessofpipeis0.025mm?6.Theorificemeter(diameteroforifice0.0001m)isinstalledformeasuringtheflowrate.Theindicatingliquidoforificeism
7、ercuryifUshapepressuregaugereadingis0.6meterandorificecoefficientcanbetakenas0.61,whatistheflowrateofwater?7.Waterflowsthroughapipewithadiameterdi100mmasshowninfigure.a.whenthevalveisclosed,Ris600mmandhequals1500mm.Whilethevalveopenspartially,R=400mmandh=1400mm,f=0.00625(Finningfa
8、ctor)andkc=0.5(contractioncoeffic
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