资源描述：
《Nikuardse trad NASA》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、C3(S3c7l-i24b4NATIONALADVISORYCOMMITTEE3FORAERONAUTICSTECHNICALMEMORANDUM1292LAWSOFFLOWINROUGHPIPESByJ.NikuradseTranslationofgStromungsgesetzeinrauhenRohren."VDI-Forschungsheft361.Beilagezu"ForschungaufdemGebietedesIngenieurwesens"AusgabeBBand4,~uly/August1933.II
2、I!iIi$iIitWashingtonfNovember1950ij11iNATIONALADVISORYCOMMITTEEFORiZERONAUTICSTECHNICALI+EMORANDUM1292ByJ.NikuradseINTRODUCTIONNumerousrecentinvestigations(references1,2,3,4,and5)havegreatlyincreasedourknowledgeofturbulentflowinsmoothtubes,channels,andalongplatess
3、othattherearenowavailablesatisfactorydataonvelocitydistribution,onthelawscontrollingresistance,onimpact,andonmixinglength.Thedatacovertheturbulentbehavioroftheseflowproblems.Thelogicaldevelopmentwouldnowindicateastudyofthelawsgoverningturbulentflowoffluidsinroughtu
4、bes,channels,andalongroughplanesurfaces.Astudyoftheseproblems,becauseoftheirfrequentoccurrenceinpractice,ismoreimportamtthanthestudyofflowalongsmoothsurfacesandisalsoofgreatinterestasanextensionofourphysicalknowledgeofturbulentflow.Turbulentflowofwaterinroughtubesh
5、asbeenstudiedduringthelastcenturybymanyinvestigatorsofwhomthemostoutstandingwillbebrieflymentionedhere.H.Darcy(reference6)madecomprehensiveandverycarefultestson21pipesofcastiron,lead,wroughtiron,asphalt-coveredcastiron,andglass.Withtheexceptionoftheglassallpipeswer
6、e100meterslongand1.2to30centimetersindiameter.Henotedthatthedischargewasdependentuponthetypeofsurfaceaswellasuponthediameterofthepipeandtheslope.IfhisresultsareexpressedinthepresentnotationandtheresistancefactorXisconsidereddependentupontheReynoldsnumberRe,thenitis
7、foundthatkaccordingtohismeasurementsA,foragivenrelativeroughness-r'variesonlyslightlywiththeReynoldsnumber(kistheaveragedepth,dofroughnessandristheradiusofthepipe;ReynoldsnumberRe=u-vinwhichtiistheaveragevelocity,disthepipediameter,andvisthekinematicviscosity).Thef
8、rictionfactordecreaseswithanincreasingReynoldsnumberandtherateofdecreasebecomesslowerforgreaterrelativeroughness.Forcertainroughnesseshisdataindi
