Effect of blocked trash rack on open channel infrastructure

Abstract

Rack clogging can produce dramatic changes in channel hydraulics. Previous studies have investigated the hydraulics of trash racks for various parameters, but the methodology and the findings were not sufficiently refined. Free-surface depression has also been neglected so far. This study considers the rack blockages as impermeable and box-shaped accumulations (instead of considering their bar thicknesses or spacings) for the hydraulic conditions. Hence, flume experiments were performed to clarify the impact of the governing variables on the rack head loss and to examine the characteristics of free-surface depression (i.e., the length of free-surface depression and maximum depth of the depression) because of predefined blockage ratios. The results prove that the rack head loss and flow turbulence behind the rack mainly depend on the rack blockage and Froude number. However, the results for the blockage ratio ≤0.13 at the approach Froude number ≤0.12 has a minor effect on the resulting rack head loss; therefore, the effects are negligible. This study proposed design equations that determine the rack head loss, length of free-surface depression, and maximum depth of the depression behind the rack because of the box-shaped accumulation body that could be used by water engineers. Furthermore, the study improves upon the process understanding of rack blockages to avoid the potential hazards of open channel infrastructure.

Investigation of Effect Garbage Level in Filtration System to Headloss and Water Discharge by Computational Method

“…Then, estimating Q in a filtration system connected to the high seas requires tidal analysis; this is because tides affect Δh and consequently affect Q. Further, Δh is directly proportional to the flow speed and the channel's width, which this similar to hypotheses of by previous studies [23,25]. Hence, the bar screen will be used as a rational Δh (head losses).…”

“…[24] against Ref. [25] is 0.003 m (≈ 0.3 cm). Thus, the equation of the analysis approach Δha is verified.…”

“…0.37 ⋅ (𝐵) 1.68 ⋅ (𝑠𝑖𝑛 𝛼) 3.5 (13) To find out Δha use: The Verifier of Sayed et al, [23] mathematical calculations was verified using the proposed equation by Sayed et al, [25]. Calculation analysis Δhb [25]:…”

Influence of Debris on Water Intake Gratings in Small Hydroelectric Plants: An Experimental Study on Hydraulic Parameters

“…The phenomenon of flow blockage in an open channel can cause changes in the hydraulics by, among other things, increasing hydraulic losses. This conclusion was reached by Zayed and Farouk [71], whose work was based on experiments conducted under laboratory conditions and explored different flow rates and blockage ratios. The authors conducted measurements in a similar water flow range of 0.020-0.040 m 3 s −1 , and they obtained 0.06-0.12 Froud's numbers and from 21,625 to 46,088 Reynold's numbers, which is close to our results, which range from 0.013-0.017 and 22,061-22,743, respectively.…”

Numerical modeling of interaction of turbulent flow with trash screen in open channels

“…The continuous hazards due to screen clogging in hydroelectric plants and turbines caused significant head loss, resulting in reduced operational efficiency or fatal operational failure. Several experimental research on-screen performances under various screen blockage instances have been carried out e.g., [2,3,4,5,6,7], and flow pattern variations caused by screen blockage results in an intensifies screen head losses, leading to a less hydraulically efficient inlet condition. The efficiency of screen blockage typically has a substantial impact on a variety of societal facets, including vital domains like infrastructure, the built environment, and economic activity.…”