Modified Venturi Channel

Abstract

Flumes having a local diminution of channel width are widely used as discharge measurement structures. The present investigation considers the modified version of a cylinder positioned axially in a nearly horizontal, prismatic channel. This particular configuration has several advantages over the usual one: determination of discharge at arbitrary, well‐defined channel cross sections needs no supplementary installations, and the device is simple and inexpensive. Moreover, the device enables a mobile registration of discharge at selected locations of a sewer or channel system. Discharge‐head relations are determined using both the traditional hydraulic approach and more sophisticated models that account for the streamline slope and curvature. Considerations include rectangular, trapezoidal and U‐shaped channels. Experiments in rectangular channels corroborate the proposed discharge‐head relation and reveal the internal flow mechanisms in the vicinity of the cylinder. Examples show the computational procedure, and graphs enable a simple application of results to problems.