DOI: 10.1615/THMT-18
ISBN Print: 978-1-56700-468-7
ISBN Online: 978-1-56700-467-0
ISSN Print: 2377-2816
Numerical verification of rapid-prototyped flexible surrogates of laboratory models of hydroturbines
RÉSUMÉ
We report on parallel experimental and numerical studies of flow, internal unsteadiness, vortex instability and associated pressure pulsations in an air model of hydroturbine draft-tube operating at off-design conditions. The air-rig, equipped with automated Laser-Doppler velocimeter and sensitive microphones, accommodates different types of surrogate turbine rotors manufactured by rapid prototyping and 3D printing, making it possible to explore a large number of different turbine and draft-tube configurations. The part-load regimes reveal in draft-tube different patterns of precessing vortex cores in form of multiple or single helical ropes, accompanied by pressure pulsations with distinct peaks at the characteristic frequencies. The complementing LES as well as some of the RANS models reproduced well the flow patterns, vortex structures and the recorded pressure pulsations, supplementing the experiments with information that are inaccessible to measurements.