Experimental Analysis on the Use of Counterflow Jets as a System for the Stabilization of the Spatial Hydraulic Jump

Abstract

This study presents an investigation on the use of submerged counterflow jets as a means for stabilizing the spatial hydraulic jump occurring in abruptly expanding channels. The characteristics of the flow downstream from the stilling basin and the main parameters influencing the effectiveness of the device in improving flow uniformity and reducing scouring potential are examined in laboratory tests, under several geometric configurations and hydraulic boundary conditions. The position within the stilling basin and the jet density (i.e., the number of orifices issuing the counterflow jets) were found to be important parameters influencing the performance of the device. Overall, the results indicate that this dissipation system has promising capabilities in forcing the transition from supercritical to subcritical flow, by significantly shortening the protection length needed to limit the phenomena of instability associated with spatial hydraulic jumps.

Experimental study of spatial hydraulic jump stabilization using lateral jet flow

“…Figure 7(b) compares the mean L j /y 1 values in the one-jet, two-jet, and non-jet modes of LJF with the Silvester (1964) and Hager (1992) equations (Equations ( 10) and ( 11), respectively). According to the observations in the hydraulic conditions leading to the S-jump, the main flow continues as a sinusoidal wave to the end of the flume (Hajialigol et al (2021) and Sharoonizadeh et al (2021) experiments also confirms this), and the first wavelength is selected as the S-jump length. It shows the possibility of erosion and scouring downstream of the basin with a length equal to Equations ( 10) and ( 11), and therefore, using the LJF system, especially with two jets, significantly affects spatial jump control.…”

“…In a spatial hydraulic jump, the main flow is centered at one side of the flume with high velocity continuing up to the end of the channel; however, upward flow occurs at the other side. The supercritical flow extends over the whole tailwater channel without completely transmitting to the subcritical flow (Sharoonizadeh et al 2021). Figure 4 indicates the flow pattern in the abruptly expanding channel equipped with LJF compared to the scenario without LJF.…”

“…In addition, the crossbeam system can improve the flow patterns in the tailwater channel and prevent any undesirable damage. Sharoonizadeh et al (2021) examined the performance of counterflow jets to stabilize spatial hydraulic jumps. They showed that jet distance from the expansion section and the jet density play an essential role in the system's performance.…”