Open this publication in new window or tab >>2018 (English)In: Journal of Fluids Engineering, ISSN 0098-2202, E-ISSN 1528-901X, Vol. 140, no 5, article id 051103Article in journal (Refereed) Published
Abstract [en]
The Winter-Kennedy (WK) method is commonly used in relative discharge measurement and to quantify efficiency step-up in hydropower refurbishment projects. The method utilizes the differential pressure between two taps located at a radial section of a spiral case, which is related to the discharge with the help of a coefficient and an exponent. Nearly a century old and widely used, the method has shown some discrepancies when the same coefficient is used after a plant upgrade. The reasons are often attributed to local flow changes. To study the change in flow behavior and its impact on the coefficient, a numerical model of a semi-spiral case (SC) has been developed and the numerical results are compared with experimental results. The simulations of the SC have been performed with different inlet boundary conditions. Comparison between an analytical formulation with the computational fluid dynamics (CFD) results shows that the flow inside an SC is highly three-dimensional (3D). The magnitude of the secondary flow is a function of the inlet boundary conditions. The secondary flow affects the vortex flow distribution and hence the coefficients. For the SC considered in this study, the most stable WK configurations are located toward the bottom from θ =30deg to 45deg after the curve of the SC begins, and on the top between two stay vanes.
Place, publisher, year, edition, pages
The American Society of Mechanical Engineers (ASME), 2018
Keywords
Winter-Kennedy, Discharge, hydropower, Spiral-case
National Category
Fluid Mechanics and Acoustics
Research subject
Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-66441 (URN)10.1115/1.4038662 (DOI)000427848100010 ()2-s2.0-85044437186 (Scopus ID)
Note
Validerad;2018;Nivå 2;2018-04-06 (svasva)
2017-11-072017-11-072022-02-10Bibliographically approved