Improvement of flow behavior in the spiral casing of Francis hydro turbine model by shape optimization
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DOI 10.1007/s12206-020-0817-9
Journal of Mechanical Science and Technology 34 (9) 2020 Original Article DOI 10.1007/s12206-020-0817-9 Keywords: · Design · Flow uniformity · Free vortex · Optimization · Response surface · Spiral casing
Correspondence to: Young-Do Choi [email protected]
Citation: Shrestha, U., Choi, Y.-D. (2020). Improvement of flow behavior in the spiral casing of Francis hydro turbine model by shape optimization. Journal of Mechanical Science and Technology 34 (9) (2020) ?~?. http://doi.org/10.1007/s12206-020-0817-9
Received January 28th, 2020 Revised
June 25th, 2020
Accepted July 6th, 2020 † Recommended by Editor Yang Na
© The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Improvement of flow behavior in the spiral casing of Francis hydro turbine model by shape optimization Ujjwal Shrestha1 and Young-Do Choi2 1
2
Graduate School of Mechanical Engineering, Mokpo National University, Muan 58554, Korea, Department of Mechanical Engineering, Institute of New and Renewable Energy Technology Research, Mokpo National University, Muan 58554, Korea
Abstract
A spiral casing is an important component of Francis hydro turbine for the even distribution of kinetic energy along the stay and guide vanes. The fluid flow around the runner is dependent on the flow condition of a spiral casing. The shape of the casing plays an important role in proper flow distribution. In this study, the optimization of the shape of a spiral casing is based on a steady-state flow analysis. Numerical optimization is performed using response surface methodology (RSM) and multiobjective genetic algorithm (MOGA). The flow uniformity and head loss in the spiral casing are selected as objectives for the optimal design of the spiral casing. The optimal design is selected from the solution acquired by RSM and MOGA. Moreover, the flow characteristics in the initial and optimal designs of the spiral casing are compared. The flow conditions in the optimal design improve significantly with the optimal design of the spiral casing. Thus, the inlet conditions for the stay vane are improved with the optimal design of the spiral casing.
1. Introduction Hydropower is a clean and renewable source of energy. The contribution of hydropower is enormous in renewable energy. According to the International Hydropower Association, 1292 GW was installed worldwide in 2018 [1]. The Francis hydro turbine is the most widely preferred turbine for the extraction of hydro potential. It is composed of a spiral casing, a stay vane, a guide vane, a runner, and a draft tube. These components have their significance regarding the overall performance of the Francis hydro turbine. The fluid flow through the component of Francis hydro turbines is a complex phenomenon due to the curvilinear trajectory [2]. However, an extensive literature regarding the flow field in Francis hydro turbine components indicates that understanding the flow pattern throughout the spiral casing is difficult. The spiral casing has
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