1、Designation:D509602(Reapproved 2017)Standard Test Method forDetermining the Performance of a Cup Anemometer orPropeller Anemometer1This standard is issued under the fixed designation D5096;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revis
2、ion,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of the Start-ing Threshold,Distance Constant,Transfer Function,an
3、dOff-Axis Response of a cup anemometer or propeller anemom-eter from direct measurement in a wind tunnel.1.2 This test method provides for a measurement of cupanemometer or propeller anemometer performance in theenvironment of wind tunnel flow.Transference of valuesdetermined by these methods to atm
4、ospheric flow must be donewith an understanding that there is a difference between thetwo flow systems.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and heal
5、th practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1356 Terminology Relating to Sampling and Analysis ofAtmospheresD3631 Test Methods for Measuring Surface AtmosphericPressure3.Terminology3.1 For definitions of terms used i
6、n this standard,refer toTerminology D1356.3.2 Definitions of Terms Specific to This Standard:3.2.1 starting threshold(Uo,m/s)the lowest wind speed atwhich a rotating anemometer starts and continues to turn andproduce a measurable signal when mounted in its normalposition.The normal position for cup
7、anemometers is with theaxis of rotation vertical,and the normal position for propelleranemometers is with the axis of rotation aligned with thedirection of flow.Note that if the anemometer axis is notaligned with the direction of flow,the calculated wind speedcomponent parallel to the anemometer axi
8、s is used to deter-mine starting threshold.3.2.2 distance constant(L,m)the distance the air flowspast a rotating anemometer during the time it takes the cupwheel or propeller to reach(1 1 e)or 63%of the equilibriumspeed after a step change in wind speed(1).3The response ofa rotating anemometer to a
9、step change in which wind speedincreases instantaneously from U=0 to U=Ufis(2):Ut5 Uf1 2 e2t/!(1)where:Ut=is the instantaneous indicated wind speed at time t inm/s,Uf=is the final indicated wind speed,or wind tunnel speed,in m/s,t=is the elapsed time in seconds after the step changeoccurs,and=is the
10、 time constant of the instrument.Distance Constant is:L 5 Uf(2)3.2.3 transfer function(f=a+bR,m/s)the linear rela-tionship between wind speed and the rate of rotation of theanemometer throughout the specified working range.fis thepredicted wind speed in m/s,a is a constant,commonly calledzero offset
11、,in m/s,b is a constant representing the windpassage in m/r for each revolution of the particular anemometercup wheel or propeller,and R is the rate of rotation in r/s.Itshould be noted that zero offset is not the same as startingthreshold.In some very sensitive anemometers the constant a,zero offse
12、t,may not be significantly greater than zero.Theconstants a and b must be determined by wind tunnel measure-ment for each type of anemometer(3).3.2.4 off-axis response(U/(Ufcos)the ratio of theindicated wind speed(U)at various angles of attack()to theindicated wind speed at zero angle of attack(Uf)m
13、ultiplied by1This test method is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.11 on Meteorology.Current edition approved March 1,2017.Published October 2011.Originallyapproved in 1990.Last previous edition approved in 2011 as D5096 0
14、2(2011).DOI:10.1520/D5096-02R17.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The boldface numbers in parenthes
15、es refer to the list of references at the end ofthis standard.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established
16、in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 the cosine of the angle of attack.This ratio compares the actualoff-axis response to a cosine response.3.3 Symbols:a(m/s)=zero offset constantb(m/r)=wind passage(apparent pitch)constant orcalibration constantL(m)=distance constantr(none)=a shaft revolutionR(r/s)=rate of rotation(s)=time constantt(s)=timeUo(m/s)=s
