1、 Reference number ISO 13550:2002(E) ISO 2002INTERNATIONAL STANDARD ISO 13550 First edition 2002-04-01 Hydrometric determinations Flow measurements in open channels using structures Use of vertical underflow gates Dterminations hydromtriques Mesure de dbit dans les canaux dcouverts au moyen de struct
2、ures Emploi de portes verticales passage subaquatique ISO 13550:2002(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and inst
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5、please inform the Central Secretariat at the address given below. ISO 2002 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in wri
6、ting from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2002 All rights reserved ISO 13550:20
7、02(E) ISO 2002 All rights reserved iiiContents Page Foreword.iv 1 Scope 1 2 Normative references1 3 Terms, definitions and symbols.1 4 Units of measurement.2 5 General requirements2 5.1 General2 5.2 Site selection2 5.3 Installation conditions.3 6 Maintenance .4 7 Measurement of head4 7.1 General4 7.
8、2 Stilling or float well4 7.3 Zero setting 5 8 Vertical underflow gates .5 8.1 Description of vertical underflow gates 5 8.2 Location of the head measurement section .7 8.3 Location of the tailwater level measurement section7 8.4 Flow types 7 8.5 Operational requirements and recommendations .9 9 Dis
9、charge relationships9 9.1 Discharge equations and coefficients for two-dimensional flow .9 9.2 Three-dimensional gate flow 13 9.3 Limits of application15 9.4 Uncertainty of measurement 15 9.5 Example of computation.15 10 Uncertainties in flow measurement .17 10.1 General17 10.2 Sources of error.17 1
10、0.3 Kinds of error .18 10.4 Uncertainties 18 10.5 Presentation of results20 10.6 Examples 20 Bibliography24 ISO 13550:2002(E) iv ISO 2002 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies).
11、The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-g
12、overnmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3
13、. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a
14、vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 13550 was prepared by Technical Committee ISO/TC 113, Hydrometric determinati
15、ons, Subcommittee SC 2, Notches, weirs and flumes. INTERNATIONAL STANDARD ISO 13550:2002(E) ISO 2002 All rights reserved 1Hydrometric determinations Flow measurements in open channels using structures Use of vertical underflow gates 1 Scope This International Standard specifies methods for the deter
16、mination of discharge in open channels in steady flow conditions using vertical underflow gates on a flat horizontal floor between vertical side walls under modular or non- modular conditions. NOTE Generally, gate controls are not designed with discharge determination as a primary function and this
17、International Standard is intended to help the development of stage-discharge relations at existing gate structures, and to incorporate into new structures features which will provide good facilities for the establishment of stage-discharge relations. When a better accuracy of measurement (i.e. bett
18、er than specified in 9.4) is required, the structure is to be calibrated with actual measurement of discharge using an appropriate method. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International St
19、andard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated
20、 below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 772, Hydrometric determinations Vocabulary and symbols ISO 4373, Measurement of liquid flow in open channels Wat
21、er-level measuring devices ISO/TR 5168, Measurement of fluid flow Evaluation of uncertainties 3 Terms, definitions and symbols For the purposes of this International Standard, the terms, definitions and symbols given in ISO 772 apply together with the following. 3.1 vertical underflow gate vertical
22、gate situated in a channel of rectangular cross-section with a flat bottom for regulating the water level upstream of the gate or the discharge through the gate opening NOTE 1 The gate is movable in vertical slots and it can be raised or lowered by hand or mechanically. NOTE 2 The underflow is two-d
23、imensional except at vertically narrow gate openings. ISO 13550:2002(E) 2 ISO 2002 All rights reserved 4 Units of measurement The units of measurement used in this International Standard are SI units. 5 General requirements 5.1 General Conditions regarding preliminary survey, selection of site, appr
24、oach channel, installation and maintenance of structures, gauge wells and measurement of head which are generally necessary for flow measurement are given in 5.2 and 5.3. The operational requirements for vertical underflow gates are given separately in 8.5. 5.2 Site selection A preliminary survey sh
25、all be made of the physical and hydraulic features of the proposed site, to check that it conforms (or can be made to conform) to the requirements necessary for the discharge determination using gates. Particular attention shall be paid to the following features: a) existence of an adequate length o
26、f channel of regular cross-section; b) flow velocity distribution; c) absence of a steep channel, if possible; d) effects of any increase in upstream water level due to the measuring structure; e) sediment content of the stream and possibility of deposition of floating debris just upstream of the ga
27、te, affecting its performance; f) permeability of the ground on which the structure is to be founded and the need for piling, grouting or other means of controlling seepage; g) necessity for flood banks to confine the maximum discharge to the channel; h) stability of the banks and the necessity for
28、trimming and/or revetment of natural channels; i) removal of rocks or boulders from the bed of the approach channel; j) effects of wind, which can have a considerable effect on the flow in a river or under a gate, especially when the channel is wide and the head is small, and when the prevailing win
29、d is in a transverse direction; k) in a natural channel, the necessity or otherwise to provide facilities for the passage of fish. If the site does not possess the characteristics necessary for satisfactory measurement, the site shall be rejected unless suitable improvements are practicable. If an i
30、nspection of the stream shows that the existing velocity distribution is regular, then it may be assumed that the velocity distribution will remain satisfactory after the construction of the gate. If the existing velocity distribution is irregular and no other site for a gauge is feasible, the distr
31、ibution shall be checked after the installation of the gate and improved if necessary. Several methods are available for obtaining a more precise indication of irregular velocity distribution. Velocity rods, floats or concentrations of dye can be used in small channels, the latter being useful in ch
32、ecking conditions at the bottom of the channel. A complete and quantitative assessment of velocity distribution may be made using a current meter. Further information on the use of current meters is given in ISO 748. ISO 13550:2002(E) ISO 2002 All rights reserved 35.3 Installation conditions 5.3.1 G
33、eneral The complete measuring installation consists of an approach channel, a measuring structure and a downstream channel. The condition of each of these components affects the overall accuracy of the measurements. Installation parameters include such features as gate finish, cross-sectional shape
34、of channel, channel roughness and the influence of the control section of devices upstream or downstream of the gauging structure. The distribution and direction of velocity have an important influence on the performance of a gate, which is determined by the features mentioned above. Once an install
35、ation has been designed and constructed, the user shall avoid any change which could affect the discharge characteristics. 5.3.2 Approach channel On all installations the flow in the approach channel shall be smooth, free from disturbance and shall have a velocity distribution as normal as possible
36、over the cross-sectional area. These criteria can usually be verified by inspection or measurement. In the case of natural streams or rivers, they can only be met by a long straight approach channel free from projections either at the side or on the bed. Unless otherwise specified in the appropriate
37、 clauses, the approach channel shall comply with the following general requirements. The change in flow conditions due to construction of the gate may cause build-up of floating debris upstream of the structure, which in time might affect the flow conditions. In an artificial channel, the cross-sect
38、ion shall be uniform and the channel shall be straight for a length equal to at least five times its width measured from the upstream side of the abutments. If entry of the approach channel is through a bend or if the flow is discharged into the channel through a conduit of smaller cross-section, or
39、 at an angle, then a greater length of straight approach channel will be required to achieve a regular velocity distribution. Baffles in the approach channel shall not be closer to the point of measurement than a distance of 10 times the maximum head to be measured. Under certain conditions, a stand
40、ing wave may occur upstream of the gauging device, for example if the approach channel is steep. Provided this wave is at a distance of not less than 30 times the maximum head upstream, flow measurement will be feasible, subject to confirmation that a regular velocity distribution exists at the appr
41、oach to the weir. If a standing wave occurs within this distance, the approach conditions and/or the gauging device shall be modified. 5.3.3 Measuring structure The structure shall be rigid, watertight and capable of withstanding flood flow conditions without displacement, distortion or fracture. It
42、 shall be at right angles to the direction of flow and shall conform to the dimensions given in the relevant clauses. The surface of the sill and the side walls of the channel in which the gate is located shall be smooth, particularly in the section from some distance upstream to some distance downs
43、tream of the gate. The bottom, sill and side walls may be constructed of concrete with a smooth cement finish. The lower edge of the gate shall be horizontal, regular in shape and straight. ISO 13550:2002(E) 4 ISO 2002 All rights reserved The construction shall satisfy the following tolerances: on t
44、he width of the channel (b) in which the gate is located: 0,5 % of the width; on point deviations from a plane surface of the flat bottom: 0,2 % of b, with an absolute maximum of 0,01 m; on point deviations from a horizontal plane of the lower edge of the gate: 0,2 % of b, with an absolute maximum o
45、f 0,01 m. 5.3.4 Downstream of the structure The channel downstream of the structure is usually of no importance if the weir has been designed to operate under modular conditions. However, if the weir is designed to measure the flow under non-modular conditions, the downstream channel shall be straig
46、ht for a length of at least eight times the maximum head to be measured. In that case, the flow shall be subcritical at the downstream face of the gate. A downstream gauge shall be provided to obtain the submergence ratio. An additional gauge located a short distance just downstream of the gate is r
47、ecommended to check the existence of modular or non-modular flow. 6 Maintenance Maintenance of the measuring structure and the approach channel is an important factor for accurate continuous measurements. It is essential that the approach channel to the gates and the channel downstream of the gates
48、be kept clean and free from silt and vegetation as far as is practicable for at least the distances specified in 5.3.2 and 5.3.4. The float well and the entry from the approach channel shall also be kept clean and free from deposits. The gate structure shall be kept clean and free from clinging or f
49、loating debris, and care shall be taken during cleaning to avoid damage to the gate. 7 Measurement of head 7.1 General The heads upstream and downstream of the measuring structure may be measured by a hook gauge, point gauge or staff gauge where spot measurements are required, or by a float-operated recording gauge or presssure-sensing gauge where a continuous record is required. It is preferable to measure heads in a separate stilling well to reduce the effects of water surface irregularities. Other head measuring methods may
