ISO 18481:2017 液体计量 液体流量测量、使用端部深度法在有自由落体的通道

标准编号：ISO 18481:2017

中文名称：液体计量 液体流量测量、使用端部深度法在有自由落体的通道

英文名称：Hydrometry — Liquid flow measurement using end depth method in channels with a free overfall

发布日期：2017-12

标准范围

This document specifies a method for the estimation of the sub-critical flow of clear water in a smooth, essentially horizontal channel (or a gently sloping channel), abruptly discontinued at bottom by a hydraulic structure, with a vertical drop and discharging freely. Such an overfall forms a control section and offers a means for the estimation of flow using the end depth measurement method. A wide variety of channel cross-sections with overfall have been studied, but only those which have received general acceptance after adequate research and testing, and therefore do not require in situ calibration, are 
considered. This document covers channels with the following types of cross-sections:
a) rectangular with confined and unconfined nappe;
b) trapezoidal;
c) triangular;
d) circular;
e) parabolic.
The flow at the brink is curvilinear; therefore, the measured depth at the drop is not equal to the critical depth as computed by the principle based on assumption of parallel flow. However, the end depth and the critical depth (as in the case of the assumption of parallel flow) have unique relation, which is used to estimate the flow through these structures.

标准预览图