Towards an optimum pitch to chord ratio and establishing its scaling effects in low head Kaplan propellers

Yang, SS and Zhao, E and Fang, T and Kesharwani, S and Chaudhary, S and Singh, P (2023) Towards an optimum pitch to chord ratio and establishing its scaling effects in low head Kaplan propellers. In: Renewable Energy, 204 . pp. 750-772.

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Abstract

Notwithstanding the long historic journey of Kaplan turbines for hydropower generation, the inner design details like position of guide vane relative to runner, blade pitch to chord ratio amongst others are yet to be investigated in depth let alone being standardized. This dearth widens in small capacity hydropower plants. The current study chooses the blade pitch to chord as research theme to be investigated both experimentally and numerically on a medium-high specific speed Kaplan turbine. Three levels of study are envisaged for obtaining the optimum ratio. The first is the change of blade number with chord fixed, the second is fixing the blade number and changing the chord length and final level of keeping the ratio constant by varying the pitch and chord by identical proportion attempts to clarify the scaling effects. Optimum efficiency in the range of 78%–82% for ratios 1.2 to 2.2 are observed for smaller pitch, smaller chord condition. The scaling study at optimum ratio revealed that increasing the blade pitch distance causes the exit fluid deflection deteriorating the performance. The paper strongly recommends a wider pitch-chord ratio study in higher specific speed Kaplans to get standardized scaling effects with respect to size and achieve universality.

Item Type:	Journal Article
Publication:	Renewable Energy
Publisher:	Elsevier Ltd
Additional Information:	The copyright for this article belongs to Elsevier Ltd.
Keywords:	Axial flow turbine: specific speed: fluid deflection: scaling: pitch to chord ratio
Department/Centre:	Division of Mechanical Sciences > Centre for Sustainable Technologies (formerly ASTRA)
Date Deposited:	10 Feb 2023 04:20
Last Modified:	10 Feb 2023 04:20
URI:	https://eprints.iisc.ac.in/id/eprint/80136

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