Comparative Numerical Analysis for Prediction of Flow Characteristics of Butterfly Valve and Vertical-lift Gate at the Penstock Inlet in Rasuwagadhi Hydropower Project

Abstract

In a hydropower project, either a valve or a gate can be selected as the penstock isolation equipment depending on cost, availability of access roads and other operational preferences. This study presents a comparative analysis of the flow characteristics between the Butterfly Valve and the Vertical-lift Gate at the penstock inlet of Rasuwagadhi Hydropower Project by conducting a three-dimensional study to identify the better alternative. The Gate and the Valve exhibit distinct geometries even in their fully open states resulting in different flow behaviors, which influences the incurred head loss and subsequently the power production and revenue of the project. The findings of the study reveal that the Vertical-lift Gate outperforms the Butterfly Valve with a higher flow coefficient, lower loss coefficient, and lesser head loss. And, considering the variations in both the initial costs and the revenue loss, the Vertical-lift Gate emerges as the more financially favorable option. The Vertical-lift Gate is found to be a better option from both the hydraulic and financial standpoint. The insights gained from this research can guide future decision-making in hydropower projects, optimizing the efficiency and financial viability of penstock isolation systems.