Тип публикации: статья из журнала
Год издания: 2017
Идентификатор DOI: 10.1016/j.ijheatfluidflow.2016.05.007
Ключевые слова: Hybrid RANS-LES, hydroturbine, Second-moment closure, vortex rope
Аннотация: Recognizing the limitations of the conventional linear-eddy-viscosity (LEVM) Reynolds-averaged Navier–Stokes (RANS) models to reproduce complex three-dimensional unsteady flows in hydraulic machinery, we performed a comparative assessment of a second-moment (Re-stress model, RSM) RANS closure and a hybrid RANS/LES method in capturiПоказать полностьюng the flow and vortical structures in the draft tube of a Francis hydroturbine at off-design conditions. Considered is a case of part load (PL) at a flow rate of only 35% of the best efficiency point (BEP) characterised by multiple unsteady vortex systems. Despite some remaining uncertainties in generating the inflow conditions, both approaches reproduced reasonably well the measured mean velocity and the rms of its fluctuations, as well as the pressure spectrum with peaks detecting the precessing vortex core. In contrast to the common LEVMs, the Re-stress closure showed sufficient receptivity to intrinsic unsteadiness and reproduced well the overall flow and vortical patterns as well as the associated pressure pulsations in accord with the experiments. The hybrid RANS/LES method gave similar predictions as the RSM, but resolving a wider range of scales, which however, showed no significant effect on the dynamics of the dominant processing vortex core and the pressure pulsations.
Журнал: International Journal of Heat and Fluid Flow
Выпуск журнала: Т. 63
Номера страниц: 158-171
ISSN журнала: 0142727X
Издатель: Elsevier Science Publishing Company, Inc.