ASTMD448093mOi’5=l530052423935TmDesignation:D4480-93AMERICANSOCIETYMRTESTINGANDMATERIALS1916RaceSt.Philadelphia,Pa19103ReprintedfromtheAnnual&okofASTMStandards.CopyrigMASTMIfnotlistedinthecurrentcombinedindex.willappearinthenetiedKinStandardTestMethodforMeasuringSurfaceWindbyMeansofWindVanesandRotatingAnemometers’ThisstandardisissuedunderthefixeddesignationD4480;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthetaxofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapprowl.Asuperscriptepsilon(0indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethoddescribesthemeasurementofhori-zontalwindvelocitybymeansofcommerciallyavailablerotatinganemometersandwindvanesattachedtotheearth’ssurfaceintheambientatmosphere.Windspeedscanbemeasuredintherangeof0.2to100m/susingsuchanemometers.Allwinddirectionsmaybemeasuredbycommerciallyavailablewindvaneswithintheoperatingspeedrange.1.2Thisstandarddoesnotpurporttoaddressallofthesafetyproblems,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoconsultandestablishappropriatesafetyandhealthpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.2.ReferencedDocument2.1ASTMStandard:D5096TestMethodforDeterminingthePerformanceofaCupAnemometerorPropellerAnemometes3.Terminology3.1Definitions:3.1.1dampednaturalfrequency(Hz)-thefrequencyatwhichadampedsecond-ordersensor(orrecorder,etc.)oscillatesafterbeingdisturbed.3.1.2dampednaturalperiods-theperiodrequiredbyadampedsecond-ordersensortoundergoonecompleteoscil-lation;alsothereciprocalofdampednaturalfrequency.3.1.3dampednaturalwavelength-theproductofthespeedofthewindpastawindvaneandthedampednaturalperiodofthewindvane.AtsealevelintheU.S.standardatmosphere,dampednaturalwavelengthisrelatedtodelaydistance,D,anddampingratiobytheapproximateexpres-sion:xd=0[6.0-2.4~1Jc7(1)3.1.4dampingratio-theratiooftheactualdampingcoefficienttothecriticaldampingcoeffkient.Thedampingratiotisdetermi...
