Application of multi-objective Bayesian shape optimisation to a sharp-heeled Kaplan draft tube
| Autor: | SJ Daniels, Jonathan E. Fieldsend, Gavin Tabor, Richard M. Everson, Alma A. M. Rahat |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
021103 operations research
Control and Optimization business.industry Mechanical Engineering 0211 other engineering and technologies Aerospace Engineering 02 engineering and technology Inflow Computational fluid dynamics Diffuser (thermodynamics) Draft tube Design objective 0202 electrical engineering electronic engineering information engineering Range (statistics) 020201 artificial intelligence & image processing Outflow Electrical and Electronic Engineering business Software Civil and Structural Engineering Marine engineering Mathematics Kaplan turbine |
| Popis: | The draft tube of a hydraulic turbine plays an important role for the efficiency and power characteristics of the overall system. The shape of the draft tube affects its performance, resulting in an increasing need for data-driven optimisation for its design. In this paper, shape optimisation of an elbow-type draft tube is undertaken, combining Computational Fluid Dynamics and a multi-objective Bayesian methodology. The chosen design objectives were to maximise pressure recovery, and minimise wall-frictional losses along the geometry. The design variables were chosen to explore potential new designs, using a series of subdivision-curves and splines on the inflow cone, outer-heel, and diffuser. The optimisation run was performed under part-load for the Kaplan turbine. The design with the lowest energy-loss identified on the Pareto-front was found to have a straight tapered diffuser, chamfered heel, and a convex inflow cone. Analysis of the performance quantities showed the typically used energy-loss factor and pressure recovery were highly correlated in cases of constant outflow cross-sections, and therefore unsuitable for use of multi-objective optimisation. Finally, a number of designs were tested over a range of discharges. From this it was found that reducing the heel size increased the efficiency over a wider operating range. |
| Databáze: | OpenAIRE |
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