Fluid-structure interactions in Francis turbines: A perspective review
Number of Authors: 2
2017 (English)In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 68, no 1, 87-101 p.Article in journal (Refereed) Published
Competitive electricity prices and reduced profit margins have forced hydraulic turbines to operate under critical conditions. The demand for extended operating ranges and the high efficiency of the turbine runners have forced manufacturers to produce lightweight runners. A turbine runner sometimes experiences resonance when a forced (flow-induced) excitation frequency approaches the runner’s natural frequency, resulting in failure. The cost of structural failure after commissioning is prohibitive. To attain a reliable and safe runner design, understanding of the structural response to flow-induced excitations is important. High amplitude pressure pulsations cause fatigue loading of the blades, which develop cracks over time. The amplitudes are dependent on the flow conditions, type of turbine and stator/rotor vane combinations. The structural response is dependent on the material properties, flow-induced damping and natural frequencies. Moreover, in a hydraulic turbine, changes in flow velocity from less than 1 m s−1 to over 40 m s−1 create challenges in predicting the response.
The main objective of this article is to review the studies conducted on fluid-structure interactions within hydraulic turbines. Several aspects are reviewed, such as flow-induced excitation, added mass effect, hydrodynamic damping, and blade flutter. Both experimental and numerical studies are discussed in this article. This review also discusses the consequences of an increased number of transient cycles, such as load variation, start-stop and total load rejection, on the turbines and the fatigue loading. Finally, an attempt is made to highlight the important requirements for prospective fluid-structure analysis to fill current gaps in the literature.
Place, publisher, year, edition, pages
2017. Vol. 68, no 1, 87-101 p.
Fluid Mechanics and Acoustics
Research subject Fluid Mechanics
IdentifiersURN: urn:nbn:se:ltu:diva-59712DOI: 10.1016/j.rser.2016.09.121ISI: 000391899200008ScopusID: 2-s2.0-84991706713OAI: oai:DiVA.org:ltu-59712DiVA: diva2:1034737
Validerad; 2016; Nivå 2; 2016-10-13 (andbra)2016-10-132016-10-132017-02-10Bibliographically approved