Clearance flow field characteristics of Kaplan turbine under different flange clearance

• Published in: IOP conference series. Earth and environmental science Vol. 1037; no. 1; pp. 12023 - 12032
• Main Authors: Zhang, Y L, Wu, Y B, Wei, J W, Wang, Z W, Zhou, L J
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.06.2022
• Subjects: Axial flow; Blade tips; Cavitation; Flow characteristics; Fluid flow; Leakage; Suction; Tip clearance; Turbines; Vortices; Working conditions
• ISSN: 1755-1307; 1755-1315
• DOI: 10.1088/1755-1315/1037/1/012023

Abstract Flange clearance flow is a complex flow phenomenon in axial flow units. Clearance vortex and vortex cavitation caused by it have always been the focus of research at home and abroad. In this paper, the steady cavitation calculation of Kaplan turbine with blade tip clearance width of 0.5mm, 1mm and 2mm is carried out under four working conditions. The energy characteristics, clearance flow characteristics and cavitation characteristics of the runner under different clearances are analyzed. Results show that: The energy characteristics of the runner domain are greatly affected by the tip clearance width. When ω/D increases by 1%, the power coefficient P * decreases by 0.83%~1.45%, and the efficiency η decreases by 0.3%~0.5%. With the increase of the clearance width, the diameter of the clearance leakage vortex band becomes thicker, and the vortex length gradually extends to the outflow edge of the blade, and the included Angle with the blade suction surface gradually increases. The cavitation type of the tip area is mostly leaking vortex cavitation when there is a tiny clearance. Clearance cavitation and leakage vortex cavitation grow as tip clearance rises, and the interaction between them is reinforced.