期刊名称：IOP Conference Series: Earth and Environmental Science
印刷版ISSN：1755-1307
电子版ISSN：1755-1315
出版年度：2019
卷号：240
期号：2
页码：1-11
DOI：10.1088/1755-1315/240/2/022032
出版社：IOP Publishing
摘要：The part load operation of turbines with non-regulated runner blades is often associated with the occurrence of a rotating corkscrew-shaped vortex rope in the draft tube. Due to its negative influence on power plants, this phenomenon is an important factor in the design process of a water turbine. Investigations using CFD aim to predict the draft tube flow, especially regarding the efficiency and the losses of the turbine. As there are still discrepancies between CFD simulations and experimentally gained data, a research project on this subject was initiated, including extensive measurements with 2D-Laser-Doppler-Anemometry. CFD simulations were carried out using high-resolution hybrid RANS-LES turbulence models. In this paper, the interrelation of the turbulent velocity fluctuations and the periodic vortex rope movement is being examined. Therefore, the measured data is provided time averaged and phase resolved. The specialities of the swirling flow influenced by the periodic vortex concerning the turbulence are illustrated on two planes, one downstream the runner in the cone and one at the lowest position of the draft tube. The results show good conformity with the CFD data including periodic part of the velocity fluctuations. The dependence of the velocity field on the rotating vortex rope is significantly higher in the cone than at the end of the draft tube bend.
