Physics of bad-behaved flow in 6-Nozzle Pelton turbine through dynamic simulation

• Published in: IOP conference series. Earth and environmental science 2019-03, Vol.240 (2), p.22018
• Main Authors: Lei, Han, Gaofu, Zhang, Ruzhi, Gong, Hongda, Wei, Wei, Li
• Format: Article
• Language: English
• Subjects: Cavitation; Computational fluid dynamics; Flow; Hydraulic jets; K-epsilon turbulence model; Mathematical models; Physics; Pressure head; Suction; Torque; Turbines; Turbulence models
• ISSN: 1755-1307; 1755-1315; 1755-1315
• DOI: 10.1088/1755-1315/240/2/022018

The bad-behaved flow in Pelton turbine, particularly in the runner region influences the efficiency performance of the system, sometimes brings out problems such as cavitation and efficiency loss. This paper will focus the physics of negative flow which are interaction of the cutting edge, two jets flow into the same bucket and flow towards the back side of bucket. Dynamic rotating process is numerically investigated in the runner region using CFX commercial code under one operating condition. These unsteady numerical simulations were conducted by RNG k-ε turbulence model combined with two-phase homogeneous model. Through the whole working process of the water jet on the bucket, the torque of the bucket and the whole runner is analyzed in detail. Four parts are divided as bucket head, pressure surface, suction surface and cutting edge region. This study deeply recognized the influences of two bad-behaved flows and proves that they are the main reasons of the torque decrease characteristic.