Characterization of Pressure Pulsation Propagation in a Pump‐Turbine Based on the Same‐Frequency Tracking Method

ABSTRACT Pressure pulsation is a key factor affecting the safe and stable operation of pump‐turbines. This article is based on same frequency‐tracking method on the pressure pulsation propagation characteristics of pump‐turbine during generation mode. The numerical simulation is validated by experimental study on a model pump‐turbine. The results show that under different flow rates, the low‐frequency pressure pulsation generated in the elbow section of the draft tube propagates upstream from the draft tube in a helical spiral opposite to the vortex band. The propagation path of the low‐frequency pressure pulsation is greatly affected by the flow rate after entering the runner, and the propagation paths are not the same under different flow rates. The rotational frequency, blade frequency, and their multiple pressure pulsations do not have obvious upstream and downstream propagation regularities. The pressure pulsation of blade frequency and its harmonics attenuates significantly when propagating upstream and downstream from the vaneless space, while the amplitude of the rotational frequency pressure pulsation is almost unchanged when it propagates upstream and downstream. However, the low‐frequency pressure pulsation is less attenuated when it propagates upstream and downstream. Its dissemination ability is the strongest.