Author(s): F. Murzyn; H. Chanson
Linked Author(s): Hubert Chanson
Keywords: Hydraulic jumps; Free-surface dynamics; Ultrasonic sensors; Measurements
Abstract: This paper concerns dynamic free-surface measurements performed in hydraulic jumps with Froude numbers between 3.1 and 8.5 using non intrusive ultrasonic probes. The interest was first focused on the characteristics of mean (η) and turbulent (η') levels of the air-water interface. Then they were coupled with phase-detection conductivity probes to assess the accuracy of the sensors. This allowed an accurate definition of the exact level detected by the ultrasonic displacement meters. The results showed a regular increase of the mean level over the jump (roller length). A peak of turbulent fluctuation was found on the roller whose amplitude depends upon the Froude number. Comparisons with previous studies showed a good agreement in terms of shapes and roller length estimation. Frequency analysis of the free-surface fluctuations revealed that highest frequencies in the jump are around 4 Hz. Based upon an autocorrelation analysis, the integral time scales of the air/water interface were found to be between 0.03 s and 0.12 s.
Year: 2009