ISO 4359:2022 流量測定構造 — 長方形、台形、および U 字型の水路 | ページ 2

Foreword

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This document was prepared by Technical Committee ISO/TC 113, Hydrometry, Subcommittee SC 2, Flow measurement structures.

This third edition cancels and replaces the second edition (ISO 4359:2013), which has been technically revised. It also incorporates the Amendment ISO 4359:2013/Amd.1:2017.

The main changes are as follows:

• 6.1.2 a) and 6.2.3.2 b) have been revised with respect to the flume approach conditions.
• Errors that were introduced in Amendment ISO 4359:2013/Amd.1:2017 have been corrected.
• An acknowledgement has been added that some of the specified tolerances can be difficult to achieve in some installations.
• The spreadsheets have been revised to provide further advice if parameters are outside the applicability range of the curve-fitting formulae for the relative boundary layer thickness (δ*/L).
• The first edition of this document (ISO 4359:1983) had an additional limitation requiring that the gauged head, h, be not more than 2 m. However, there is no technical justification for this restriction, so it does not appear in the second and third editions of this document.
• In 11.4.7 and 12.4.7, although the relationship of C_s with mh_e/b_e varies very slightly with flume geometry and the value of the boundary layer displacement thickness, this variation was disregarded when applying the coefficient method in the first edition of this document, as a single graphical relationship was provided for trapezoidal flumes. This approximation has been remedied in the second and third editions of this document.

1 Scope

This document specifies methods for the measurement of flow in rivers and artificial channels under steady or slowly varying flow conditions, using certain types of critical-depth flumes (also known as “standing-wave flumes”). A wide variety of flumes has been developed, but only those critical-depth flumes which have received general acceptance after adequate research and field testing, and which therefore do not require in situ calibration, are considered herein.

The flow conditions considered are uniquely dependent on the upstream head, i.e. subcritical flow must exist upstream of the flume, after which the flow accelerates through the contraction and passes through its critical depth (see Figure 1). The water level downstream of the structure is low enough to have no influence upon its performance.

This document is applicable to three commonly used types of flumes, covering a wide range of applications, namely rectangular-throated, trapezoidal-throated and U-throated. The hydraulic theory behind this document was presented in Reference [7].

This document is not applicable to a form of flume referred to in the literature (sometimes called a “Venturi” flume) in which the flow remains subcritical throughout.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 772 apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

Bibliography