Indagine sperimentale sulla localizzazione del risalto a mezzo di quinte

The paper deals with the hydraulic jump localization realized by an abrupt contraction of the section width. This contraction may be right made by two walls – the wings – located at the end of the stilling basin and structurally connected with the lateral walls. This structure ensures a major reliability to respect the stilling basin with a positive step that the sediment drift tends to reduce. A large set of laboratory experiments was made in a Froude number range spanning between 4 and 13 for several different geometrical configurations of the wings. Besides a clear highlight on the hysteresis phenomenon that characterizes the hydraulic jump localization, from the results it is manifest the relevance of the ratio between the length of the contracted width and the depth of the toe of jump in the design of the contraction ratio. Moreover, the measured basin length for the Froude range between 4 and 7 is greater that the length recommended and usually adopted.