The effect of aeration through an internal gallery of a dam on the cavitation risk of Roberts splitters

Journal of the South African Institution of Civil Engineers

Calitz, G¹ 

[1] Stellenbosch University, South Africa

关键词: Roberts splitters;    dam spillway;    energy dissipation;    artificial aeration;    cavitation.;   

DOI  :  10.17159/2309-8775/2018/v60n1a4

学科分类：建筑学

来源: South African Institution of Civil Engineering / Suid-Afrikaanse Instituut van Siviele Ingenieurswese

【 摘 要 】

Roberts splitters is an effective means of energy dissipation for dam spillways. Roberts' (1943) standard unaerated splitter design procedure is, however, limited to a spillway head (H) of 3.0 m (q ~ 12 m2/s). In order to avoid cavitation at higher design spillway heads, this study investigated the artificial aeration of the flow by local air vents positioned on the splitters. A 1:20 scale hydraulic model of an ogee spillway equipped with Roberts splitters was constructed. Two aerated models, with differently sized air vents, were compared to an unaerated control model in order to determine the effect that the proposed aeration system has on the cavitation risk of the splitters at prototype unit discharges (q) of up to 50 m2/s. At the maximum tested spillway head of 7.6 m (q = 50 m2/s) the minimum pressures and air concentration around the splitters of both aerated models increased considerably. It was further observed that the unaerated splitters were prone to drowning at high spillway heads, leading to unfavourable hydraulic conditions. Based on the results of this study, the addition of aeration through an internal aeration gallery can increase the unit discharge capacity of Roberts splitters to at least 50 m2/s, up by 43%, from the unaerated limit of 35 m2/s.

【 授权许可】

CC BY