Experimental study of the hydraulic jump on reverse bed with porous screens

Abstract

Nowadays, the porous screens have been used extensively in open channels to prevent erosion in ditches as the water in supercritical state flows past the screen which forces the formation of a hydraulic jump upstream of the screen and produces significant energy loss. In this investigation, the operation of screens has been studied for supercritical flow and the Froude number in the range of 4.5 to 10.6 on two reverse slopes experimentally. In this study, the parameters included arrangements of screens in both the single and double types, and the angle and distance of screens from the hydraulic jump toe. The screens were studied with a porosity of about 50% with square holes. The study results showed that using of screens on the reverse slope of − 0.025 dissipates more energy compared to reverse slope of − 0.015. The screens with double arrangement have better performance and dissipate more energy than the screens with single arrangement, while the distance of screens from the toe of the hydraulic jump does not have a significant effect on the energy dissipation.

Effect of different screen widths on the submerged hydraulic jump characteristics

“…The experimental tests were performed in a recirculating flume of 0.30 m in width, 0.468 m in depth and 15.6 m in length with working section of 12.50 m in length as shown in photo (1). A centrifugal pump lifts the water from a sump tank to the flume inlet.…”

“…Photo (1) The mentioned flume Screens with a 22 cm in width and 3 cm height has 24 holes with diameters 0.4, 0.6, 0.8, 1.00 and 1.2 cm with corresponding different relative holes area (Ar) 0.046, 0.103, 0.183, 0.285 and 0.411, respectively were used to investigate the effect of changing the screen passing area on the hydraulic jump characteristics. The case of no screen was considered a reference base to check the effect of screen with different relative area on the characteristics of hydraulic jump phenomenon.…”

“…A perforated sill such as screens are commonly used in prismatic channels' stilling basins to maximize the energy dissipation and minimize the hydraulic jump length and its sequent depth. (Abbaspour et al, 2019) tested the hydraulic jump characteristics on a negative bed with porous screens. The study results showed that the adverse stilling basin with screens having the ability to dissipate energy greater than that corresponding stilling basin without screen.…”

“…The results were presented in the form of mathematical models to estimate basin length the sill height, and sill position. The screen porosity was studied by (Daneshfaraz et al, 2019) (Abbaspour et al, 2019) and (Sadeghfam et al, 2015) to determine and select the best screen porosity that improve the characteristics of the hydraulic jump in the prismatic stilling basins. It was found that a screen porosity of 40% to 50% gave energy loss more than that of other porosities.…”

“…(Bozkus et al, 2007) examined a vertical screen, while an inclined screen studied by (Balkiş, 2004), it was found that the vertical screen more effective from the energy dissipation point of view. (Bozkuş et al, 2006) and (Rajaratnam and Hurtig, 2000) investigated the energy dissipation by a triangular screen, while the square screen was studied by (Abbaspour et al, 2019) and circular screens and its effect on the hydraulic jump characteristics were reported by (Cakir, 2003). It was found that the square screens dissipate energy more than that of other shapes, this finding matched closely with (Mahmoud et al, 2013).…”