This study investigates the pressure pulsation and entropy generation characteristics of an experimentally validated downscaled third-generation reactor coolant pump (RCP) model under two reverse-rotation modes: negative flow and positive flow. Numerical simulation, fast Fourier transform (FFT) analysis, and entropy generation theory were used to reveal the unsteady pressure response and irreversible loss distribution. Under negative flow, pressure pulsations in the impeller, guide vane, and volute exhibit ordered periodic features dominated by the blade-passing frequency and its harmonics, with peak amplitudes near the impeller–guide-vane transition region. Entropy generation varies non-monotonically with flow rate and reaches a minimum at 0.8 Qd , while the impeller contributes 52–78% of the total entropy generation. Under positive flow, the impeller and guide vane retain periodic pulsations, whereas the volute exhibits irregular low-frequency fluctuations. Entropy generation increases monotonically, and the guide vane becomes the dominant dissipation source, with wall entropy generation exceeding 70%. These findings clarify the mode-dependent pulsation and loss mechanisms of RCPs under reverse-rotation accident conditions.
Ye et al. (Fri,) studied this question.