简介：Thisarticlebrieflyreviewswindturbineaerodynamics,whichfollowsanexplanationoftheaerodynamiccomplexity.Theaerodynamicmodelsincludingblademomentumtheory,vortexwakemodel,dynamicstallandrotationaleffect,andtheirapplicationsinwindturbineaerodynamicperformancepredictionarediscussedanddocumented.Recentprogressincomputationalfluiddynamicsforwindturbineisaddressed.Windturbineaerodynamicexperimentalstudiesarealsoselectivelyintroduced.

简介：Aerodynamicperformanceofthehigh-altitudepropeller,especiallythecounterrotationeffects,isexperimentallystudied.Influencesofdifferentconfigurationsonastratosphericairship,included2-bladecounter-rotatingpropeller(CRP),dual2-bladesinglerotationpropellers(SRPs)and4-bladeSRP,arealsoindicated.Thisresearchindicatesthattheeffectofcounterrotationcangreatlyimprovetheefficiency.ItshowsthattheCRPconfigurationresultsinahigherefficiencythanthedual2-bladeSRPsconfigurationor4-bladeSRPconfigurationunderthesameadvanceratio,andtheCRPconfigurationalsogainsthehighestefficiencywhetherunderthesituationofprovidingthesametrustorabsorbingthesamepower.Itconcludesthat,forastratosphericairship,theCRPconfigurationisbetterthanthemultipleSRPsconfigurationoramulti-bladeSRPone.

简介：Inoffshoreengineeringdesign,itisconsiderablysignificanttohaveanadequatelyaccurateestimationofmarineenvironmentalparameters,inparticular,theextremewindspeedoftropicalcyclone(TC)withdifferentreturnperiodstoguaranteethesafetyinprojectedoperatinglifeperiod.Basedonthe71-year(1945–2015)TCdataintheNorthwestPacific(NWP)bytheJointTyphoonWarningCenter(JTWC)ofUS,anotablegrowthoftheTCintensityisobservedinthecontextofclimatechange.Thefactimpliesthatthetraditionalstationarymodelmightbeincapableofpredictingparametersintheextremeevents.Therefore,anon-stationarymodelisproposedinthisstudytoestimateextremewindspeedintheSouthChinaSea(SCS)andNWP.Wefindthattheextremewindspeedsofdifferentreturnperiodsexhibitanevidentenhancementtrend,forinstance,theextremewindspeedswithdifferentreturnperiodsbynonstationarymodelare4.1%–4.4%higherthanstationaryonesinSCS.Also,thespatialdistributionofextremewindspeedinNWPhasbeenexaminedwiththesamemethodologybydividingthewestseaareasoftheNWP0°–45°N,105°E–130°Einto45subareasof5°×5°,whereoilandgasresourcesareabundant.Similarly,remarkablespacialin-homogeneityintheextremewindspeedisseeninthisarea:theextremewindspeedwith50-yearreturnperiodinthesubarea(15°N–20°N,115°E–120°E)ofZhongshaandDongshaIslandsis73.8m/s,whilethatinthesubareaofYellowSea(30°N–35°N,120°E–125°E)isonly47.1m/s.Asaresult,thepresentstudydemonstratesthatnon-stationaryandin-homogeneouseffectsshouldbetakenintoconsiderationintheestimationofextremewindspeed.

简介：Utilizationofwindenergyisapromisingwaytogeneratepower,andwindturbinebladesplayakeyroleincollectingthewindenergyeffectively.Thispaperattemptstomeasurethedeformationparameterofwindturbinebladesinmechanicsexperimentsusingavideometricmethod.Inviewthatthebladesexperiencesmallbucklingdeformationandlargeintegraldeformationsimultaneously,weproposedaparallelnetworkmeasurement(PNM)methodincludingthekeytechniquessuchascameranetworkconstruction,c...

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简介：Thecomplexityoftheloadsactingontheoffshorewindturbines(OWTs)structuresandthesignificanceofinvestigationonstructuredynamicsareexplained.Testresultsobtainedfromascaledwindturbinemodelarealsosummarized.Themodelissupportedonmonopile,subjectedtodifferenttypesofdynamicloadingusinganinnovativeoutofbalancemasssystemtoapplycyclic/dynamicloads.Thetestresultsshowthenaturalfrequencyofthewindturbinestructureincreaseswiththenumberofcycles,butwithareducedrateofincreasewiththeaccumulationofsoilstrainlevel.Thechangeisfoundtobedependentontheshearstrainlevelinthesoilnexttothepilewhichmatcheswiththeexpectationsfromtheelementtestsofthesoil.Thetestresultswereplottedinanon-dimensionalmannerinordertobescaledtopredicttheprototypeconsequencesusingelementtestsofasoilusingresonantcolumnapparatus.

简介：Advancesinmaterialscienceandmathematicsinconjunctionwithtechnologicalneedshavetriggeredtheuseofmaterialandelectriccomponentswithfractionalorderphysicalproperties.Thispaperconsidersthemathematicalmodelofapiezoelectricwindflowenergyharvestersystemforwhichthecapacitanceofthepiezoelectricmaterialhasfractionalordercurrent-voltagecharacteristics.Additionallythemechanicalelementisassumedtohavefractionalorderdamping.Theanalysisisfocusedontheeffectsoforderofderivativesontheappearanceandcharacteristicsoflimitcircleoscillations(LCO).Itisobtainedthat,theorderofderivativestoenhancetheamplitudeofLCOandlowerthethresholdconditionleadingtoLCO.Thedomainsofefficiencyofthesystemareillustratedinvariousparametersspaces.

简介：Inthispaper,aresearchontheproblemofmultiplesolutionsofthethree-coefficientlow-spectrummodelforthequasi-geostrophicoceancurrentequationwithforcinganddissipationtermsiscarriedout.Thestateoftheoceancurrentunderwindconditionssuchasthoseoftyphoonisdiscussedcarefullyandtherela-tionsbetweenthemultiplesolutionsandthecoefficientsRandεareanalyzed.Itisseenthatinanapproxi-matetriangularregionwiththeRossby-coefficientRlessthan0.5,andthefriction-coefficientεlessthan0.22,thereexistthreeequifibriumsolutions,amongwhichtwoarestableandoneisunstable.Fortheformer,thecoefficientAorBintheexpansionisratherlarge,whileforthelatter,AorBisrelativelysmall.TheyrespectivelyimplyhowmuchtheoceanenergyisfedbackfromthewindstressandthesolutionwithalargeAismuchmorestablethanthatwithalargerB.

简介：Theprobabilitydistributionsofsandparticles'lift-offandincidentvelocitiesinawind-blownsandfluxplayveryimportantrolesinthesimulationofthewind-blownsandmovement.Inthispaper,theverticalandthehorizontalspeedsofsandparticleslocatedat1.0mmaboveasand-bedinawind-blownsandfluxareobservedwiththeaidofPhaseDopplerAnemometry(PDA)inawindtunnel.Basedontheexperimentaldata,theprobabilitydistributionsofnotonlytheverticallift-offspeedbutalsothelift-offvelocityaswellasitshorizontalcomponentandtheincidentvelocityaswellasitsverticalandhorizontalcomponentscanbeobtainedbytheequaldistancehistogrammethod.Itisfound,accordingtotheresultsoftheχ2-testfortheseprobabilitydistributions,thattheprobabilitydensityfunctions(pdf's)ofthesandparticles'lift-offandincidentvelocitiesaswellastheirverticalcomponentsaredescribedbytheGammadensityfunctionwithdifferentpeakvaluesandshapesandthedownwindincidentandlift-offhorizontalspeeds,respectively,canbedescribedbythelognormalandtheGammadensityfunctions.Thesepdf'sdependonnotonlythesandparticlediameterbutalsothewindspeed.

简介：Anewanalyticalmodelwasdevelopedtopredictthegravitywavedrag(GWD)inducedbyanisolated3-dimensionalmountain,overwhichastratified,non-rotatingnon-Boussinesqshearedflowisimpinged.Themodelisconfinedtosmallamplitudemotionandassumestheambientvelocityvaryingslowlywithheight.ThemodifiedTaylor-GoldsteinequationwithvariablecoefficientsissolvedwithaWentzel-Kramers-Brillouin(WKB)approximation,formallyvalidathighRichardsonnumbers.WiththisWKBsolution,genericformulaeofsecondorderaccuracy,fortheGWDandsurfacepressureperturbation(bothforhydrostaticandnon-hydrostaticflow)arepresented,enablingarigoroustreatmentontheeffectsbyverticalvariationsinwindprofiles.Inanidealtesttothecircularbell-shapedmountain,itwasfoundthatwhenthewindislinearlysheared,thattheGWDdecreasesastheRichardsonnumberdecreases.However,theGWDforaforwardshearedwind(windincreaseswithheight)decreasesalwaysfasterthanthatforthebackwardshearedwind(winddeceaseswithheight).Thisdifferenceisevidentwheneverthemodelishydrostaticornot.