1、Designation:D561494(Reapproved 2014)Standard Test Method forOpen Channel Flow Measurement of Water with Broad-Crested Weirs1This standard is issued under the fixed designation D5614;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the
2、 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 measurement of the volumetricflow rate of water in open channels with two types ofhorizont
3、al broad-crested weirs:those having a square(sharp)upstream corner and those having a well-rounded upstreamcorner.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand
4、are not considered standard.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 health practices and determine the applica-bility of regulatory limitations pri
5、or to use.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3858 Test Method for Open-Channel Flow Measurementof Water by Velocity-Area Method2.2 ISO Standards:3ISO55
6、5-1973 LiquidFlowMeasurementinOpenChannelsDilution Methods for Measurement of SteadyFlowConstant Rate Injection MethodISO 3846-1989 Liquid Flow Measurement in Open Chan-nels by Weirs and FlumesRectangular Broad-CrestedWeirsISO 4373-1979 Measurement of Liquid Flow in OpenChannelsWater Level Measuring
7、 DevicesISO 4374-1990 Liquid Flow Measurement in Open Chan-nels by Weirs and FlumesRound-Nose Horizontal CrestWeirs3.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 boundary layer displacem
8、ent thickness the bound-ary layer is a layer of fluid flow adjacent to a solid surface(inthis case,the weir crest and sidewalls)in which,due to viscousfriction,the velocity increases from zero at the stationarysurface to an essentially frictionless-flow value at the edge ofthe layer.The displacement
9、 thickness is a distance normal tothe solid surface that the flow streamlines can be considered tohave been displaced by virtue of the boundary-layer informa-tion.3.2.2 crestthe horizontal plane surface of the weir.3.2.3 critical flowopen channel flow in which the energy,expressed in terms of depth
10、plus velocity head,is a minimumfor a given flow rate and channel.The Froude number is unityat critical flow.3.2.4 Froude numbera dimensionless number expressingthe ratio of inertial to gravity forces in free surface flow.It isequal to the average velocity divided by the square root of theproduct of
11、the average depth and the acceleration due togravity.3.2.5 headin this test method,the depth of water above aspecified elevation.The measuring head is the depth of flowabove the weir crest measured at an appropriate locationupstream of the weir;the downstream head is referencedsimilarly to the crest
12、 elevation and measured downstream ofthe weir.The head plus the corresponding velocity head isoften termed the total head or total energy head.3.2.6 hydraulic jumpan abrupt transition from supercriti-cal flow to subcritical or tranquil flow,accompanied byconsiderable turbulence or gravity waves,or b
13、oth.3.2.7 nappethe curved sheet or jet of water overfalling thedownstream end of the weir.1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.07 on Sediments,Geomorphology,and Open-Channel Flow.Current edition approved Jan.1,
14、2014.Published March 2014.Originallyapproved in 1994.Last previous edition approved in 2008 as D5614 94(2008).DOI:10.1520/D5614-94R14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume informat
15、ion,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3
16、.2.8 primary devicethe device(in this case,the weir)thatcreates a hydrodynamic condition that can be sensed by thesecondary instrument.3.2.9 Reynolds numbera dimensionless number express-ing the ratio of inertial to viscous forces in a flow.The pertinentReynolds number on the weir crest is equal to the(critical)velocity multiplied by the crest length and divided by thekinematic viscosity of the water.3.2.10 secondary instrument in this case,a device thatmeasures the depth of flow(referenced to t
