Author(s): Xiaoyang Shen; Mario Oertel

Linked Author(s): Mario Oertel

Keywords: Piano-Key-Weir; Hydraulic structure; Hybrid modelling; Nappe behavior; Discharge efficiency

Abstract: As an innovative type of non-linear weirs, Piano-Key-Weirs has been considered as a modern techno-ecological solution for the rehabilitation of aged flood release structures. Compared to regular linear weirs, substantial improvement in discharge capacity can be achieved by its folded plan form, which allows a significant longer crest length to be accommodated within the given channel width. However, this efficiency gain decreases with increasing upstream head due to less efficient outflow over side walls and the occurrence of local submergence between the outlet sections. Up to date, previous studies have mainly focused on resulting discharge coefficients and the influence induced by the local submergence was not analyzed in detail. Within the present study, various Piano-Key-Weir models including both trapezoidal and rectangular plan forms with differentiated side wall discharge conditions were tested via hybrid modelling for comparison. The purpose is to further analyze the side wall discharge development with and without local interferences. Results show that the nappe collision between adjacent side walls has only minor influence on the final discharge capacity. Instead, the outflow over upstream linear apexes was found to be the major factor interfering with side wall discharge and inducing local submergence. Furthermore, the influence of local interference appears to vary with crest profile and actual model configuration.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p1265-cd

Year: 2023