Title: Optimisation of Francis turbine draft tube using response surface model

Authors: Ali Abbas; Arun Kumar

Addresses: Flovel Energy Pvt. Ltd., Faridabad, Haryana, 121003, India ' Hydro and Renewable Energy Department, IIT Roorkee, Rorrkee, Haridwar, 247667, India

Abstract: The draft tube design of low and medium head hydraulic turbines plays an important role in determining the efficiency and power output. Proposed Francis draft tube geometry was optimised with two different optimisation goals, i.e.: 1) rehabilitation; 2) a new design. Using the design of experiments approach, 81 design points were generated for both cases separately and response surface methodology (RSM) was used for optimisation. Two objective functions, i.e., pressure recovery (C_p) and loss factor (ζ) were considered in the optimisation process. A multi-objective genetic algorithm coupled with RSM was adapted to optimise the proposed draft tube geometry for achieving desired optimisation goal. For Case 1, optimum values of C_p and ζ value were found as 0.8290 and 0.1158, respectively. The value of pressure recovery was enhanced by 7.0% at the best efficiency point. For Case 2, an optimum value of C_p was found as 0.851 which is 10.0% higher compared with the performance of the existing draft tube.

Keywords: Francis turbine; draft tube; computational fluid dynamics; CFD; response surface methodology; RSM; design of experiment; DOE; multi-objective genetic algorithm; MOGA.

DOI: 10.1504/PCFD.2022.127198

Progress in Computational Fluid Dynamics, An International Journal, 2022 Vol.22 No.6, pp.343 - 359

Received: 25 Sep 2020
Accepted: 01 Oct 2021
Published online: 28 Nov 2022 *

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