Investigation on hydraulic loss characteristic of Kaplan turbines based on entropy generation theory

• Published in: Journal of physics. Conference series Vol. 2752; no. 1; pp. 12028 - 12034
• Main Authors: Liu, Boxing, Feng, Jianjun, Wang, Zhaoning, Guan, Ziwu, Zhu, Guojun
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.06.2024
• Subjects: Draft tubes; Entropy; Hydraulics; Pressure drop; Turbines; Turbulent flow
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/2752/1/012028

In this paper, the hydraulic losses of a Kaplan turbine under optimal and rated operating conditions are investigated through the theory of entropy generation. The results show that hydraulic loss values calculated using pressure drop and entropy generation theory are similar. The hydraulic losses are mainly concentrated in runner and draft tube. However, when the operation condition of Kaplan turbines deviates from the optimal condition, the proportion of hydraulic loss in draft tube increases. The hydraulic loss in draft tube is mainly composed of entropy generation caused by turbulence fluctuation, which is the result of unstable flow induced by vortex rope. The hydraulic losses of other parts are mainly composed of entropy production caused by wall shear. The high entropy production of the runner concentrated on the shroud, hub, blade surface, and blade trailing edge, while entropy production caused by wall shear is concentrated on blade pressure surface and shroud near blades when the turbine strays from optimal operating condition.