Optimal Control of Part Load Vortex Rope in Francis Turbines

The mitigation of the precessing vortex core developing in the draft tube of Francis turbines operating under part load conditions is crucial to increase the operation flexibility of these hydraulic machines to balance the massive power production of intermittent energy sources. A systematic approach following the optimal control theory is, therefore, presented to control this vortical flow structure. Modal analysis characterizes the part load vortex rope as a self-sustained instability associated with an unstable eigenmode. Based on this physical characteristic, an objective function targeting a zero value of the unstable eigenvalue growth rate is defined and subsequently minimized using an adjoint-based optimization algorithm. We determine an optimal force distribution that successfully quenches the part load vortex rope and sketches the design of a realistic control appendage.


Published in:
Journal Of Fluids Engineering-Transactions Of The Asme, 141, 8, 081203
Year:
Aug 01 2019
Publisher:
New York, ASME
ISSN:
0098-2202
1528-901X
Keywords:
Laboratories:




 Record created 2019-06-28, last modified 2019-08-30


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