https://orcid.org/0000-0003-2989-758X
![Sample our Economics, Finance,Business & Industry journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5931/TOC-Subject-Sample-2021-Economics-Finance-Business-Industry.jpg"})
ABSTRACT
This study examines the scouring effect downstream of a type-A trapezoidal stepped Piano key weir using experimental methods. The experiments were performed on weirs, both with and without steps at the outlet keys, while considering various discharge rates, tailwater depths, and bed material sizes. The study scrutinized three unique weir configurations, each with different dimensions and step counts at the outlet keys: the first, second, and third weirs had 5, 10, and 15 steps respectively. The findings indicate that the maximum scour depths in the Piano key weirs with 5, 10, and 15 steps were, on average, 17.5%, 31%, and 19% less than those in the non-stepped weir. It was also noted that an increase in discharge and a decrease in tailwater depth and bed material size led to an increase in the maximum scour depth. Moreover, an increase in the number of steps and a decrease in the size of the bed materials resulted in a reduction in sediment ridge height. The analysis suggests that the average scour index values in the 10-stepped weir were about 21% lower compared to the non-stepped weir. These insights contribute to the design and optimization of hydraulic structures to effectively mitigate scouring effects.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Notation
| B | = | lateral wall length (m) |
| Bi | = | upstream overhanging length (m) |
| Bo | = | downstream overhanging length (m) |
| Cc | = | curvature coefficient (-) |
| Cu | = | uniformity coefficient (-) |
| d50 | = | mean diameter (m) |
| Fr | = | Froude number (-) |
| Frd | = | particle Froude number (-) |
| G | = | acceleration of gravity (m/s2) |
| G | = | gravel materials (-) |
| hs | = | step height (m) |
| Hu | = | total flow head upstream of weir (m) |
| Ls | = | streamwise length of step (m) |
| Ns | = | number of steps (-) |
| P | = | weir height (m) |
| Q | = | discharge per unit width (m2/s) |
| Q | = | discharge (m3/s) |
| Re | = | Reynolds number (-) |
| S | = | sand materials (-) |
| Si | = | scour index (-) |
| Ts | = | Weir wall thickness (m) |
| W | = | weir width (m) |
| We | = | Weber number (-) |
| Wi | = | inlet key width (m) |
| Wo | = | outlet key width (m) |
| XR | = | length of sediment ridge from weir (m) |
| XRmax | = | distance of location of maximum sediment ridge from weir (m) |
| XS | = | scour hole length (m) |
| Xsmax | = | distance of maximum scour depth from weir (m) |
| Yt | = | total flow head downstream of weir (m) |
| yt | = | tailwater depth (m) |
| ZF | = | maximum weir toe scour depth (m) |
| ZRmax | = | maximum height of sediment ridge (m) |
| Zsmax | = | maximum scour depth (m) |
| ∆H | = | energy difference between upstream and downstream of weir (m) |
| µ | = | dynamic viscosity (kg/m.s) |
| ρs | = | sediment density (kg/m3) |
| ρw | = | water density (kg/m3) |
| Σ | = | surface tension coefficient (kg/s2) |
| σg | = | standard deviation (-) |