An Experimental Channel for the Study of Air Entrainment in High-Velocity Flow

Abstract

A large open channel designed for the study of self-aeration of high-velocity flows has been built and installed at the Laboratory. This 50-ft channel has a cross section 12 in. deep and 18 in. wide and can be set at any slope from horizontal to vertical. The slope is controlled by means of a hydraulic system and is indicated with a servo system with an accuracy of 1/4 degree. The initial flow depth in the test flume is controlled by an electrically driven sluice gate with a rounded entrance located at the head of the flume. This depth can be controlled and indicated within 0.001 ft throughout its 1/4-in. to 6-in. range. The water discharge is regulated by two hydraulically operated gate valves in the supply lines and is measured within an accuracy of about 1-1/2 per cent. The inlet region is designed to produce an initially uniform jet at terminal velocity, and the flume is long enough to permit the aeration process to reach equilibrium for a range of discharge at all slopes. The selection of these flume dimensions and performance limits of the installation are explained from present knowledge of aerated flows and from aerated flow measurement requirements.