Abstract
In this study, curved risers stepped spillways models based on the increasing angle of suspension were tested to check for improvement in energy dissipation and pressure distributions. Four fourteen-steps stepped spillway models with a slope 1:0.84 were selected, using Froude’s number non-dimensional similarity. The risers of steps were made curved, based on three angles of suspensions, i.e., 30°, 60°, and 90°. The simulations were performed by FLOW 3D software and by the turbulence model Renormalization Group (RNG) for discharges between 0.020 and 0.068 m3/s followed by the model calibration. The 3D Reynolds-averaged Navier–Stokes equations were solved, which included sub-grid models for air entrainment, density evaluation, and drift–flux, to capture free-surface flow over the stepped spillway. It was estimated that curving the risers increases the energy dissipation up to three percent for lower flow rates, whereas it has no significant impact on energy dissipation for higher flow rates. It was found that in simply stepped spillway lower steps dissipate more energy as compared to curved risers stepped where energy dissipation is shifted to higher steps. On the other hand, curved risers stepped spillways showed lower values of negative pressures as compared to the simply stepped spillway. It was seen that a higher energy dissipating step as experienced more negative pressures as compared to the lower energy dissipating step.
Highlights
Spillways are the integral part of the dam as they allow safe passage of overtopping flow [1]
Nape flow usually occurs at small flow rates and total fall is divided into number of smaller free fall, while skimming flow occurs at high flow rates and flow occurs as a coherent stream over the steps with recirculation trapped within the steps [7]
The primary purpose of the study was to evaluate the impact of alteration in step geometry on flow parameters such as pressure and energy dissipation across the stepped spillway model using the latest CFD software package FLOW3D
Summary
Spillways are the integral part of the dam as they allow safe passage of overtopping flow [1]. Stepped spillways contain steps that induce the macro roughness and project the high turbulence in flow [3]. As compared to simple ogee spillways, they offer more loss of kinetic energy of flowing water [4]. Stepped spillways have gained more interest due to their compatibility with roller compacted concrete dams [5]. Flow over the steps spillway is divided into three regimes: (1) nape flow; (2) transition flow; and (3) skimming flow [6]. Nape flow usually occurs at small flow rates and total fall is divided into number of smaller free fall, while skimming flow occurs at high flow rates and flow occurs as a coherent stream over the steps with recirculation trapped within the steps [7]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
