開水路断面変化部における流れの水理特性について (2)-水路幅急変部に関する実験的検討-

Abstract

This paper deals with the characteristics of an open channel flow around a suddenwidth-expansion or -contraction. The velocity measurements are carried out with a hot-film flowmeter and a propeller flowmeter. Three dimensional distributions of mean andturbulent velocity, the energy and the momentum coefficients, the Reynolds stress areobtained experimentally. Some interesting results about the bed-variation around a suddenwidth-expansion or -contraction are obtained experimentally.Main results obtained through experimental investigations are as follows; 1) The char-acteristics of mean velocity distribution depend on the expansion or contraction ratioand the kind of flow transition, that is, sub-critical or supercritical transitions. 2) Theenergy and the momentum coefficient of flow in transition have values more than unity.3) The existence of spiral motion is found in the flow through the section of suddencontraction. 4) The energy spectrum of turbulence show the existence of the inertial sub-range which is descriced by the power low of -5/3.