Experimental Study of Transient Flow Regimes in a Model Hydroturbine Draft Tube

Swirling flow with the formation of a precessing vortex core (PVC) in draft tube model hydroturbine was studied. Experiments were performed on an aerodynamic setup under transient operating conditions hydroturbine. The turbine varied by continuously changing rate at constant runner speed. transition from partial load regime, when is formed, to best efficiency point without considered. Applied this task, comparison windowed Fourier transform wavelet analysis given. dependence PVC lifetime regime correlates time. It shown that velocity profiles and spectrum pressure pulsations regimes change quasistatically between part-load operation turbine. phase-averaged distributions show sequence quasisteady regimes.