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：1-9
DOI：10.1088/1755-1315/240/2/022010
出版社：IOP Publishing
摘要：It is well known that the spiral vortex (or vortex rope) is developed in the conical diffuser of hydraulic turbines with fixed pitch blades (e.g. Francis and propeller) when operating conditions are far away from best efficiency point. The paper will present a new technique in order to mitigate, even eliminate the bad behave associated to this phenomenon. By injecting a pulsating water jet, along the cone axis, the unsteady pressure fluctuations given by the vortex rope are mitigated. Our investigations are performed on the test rig from Politehnica University. In order to assess the velocity profiles given by the swirling flow with and without pulsating water jet, an extensive 3D numerical simulations were performed. Second, the experimental data of pressure fluctuations was analysed. This technique, shows that the pressure recovery is improved and the hydraulic losses decreases along the conical diffuser. Also, it is shown that the stagnant region associated to the spiral vortex is mitigated since the pulsating jet is introduced. Also, the pressure fluctuations are mitigated.
