Research on pressure pulsation characteristics of reactor coolant pump under non-uniform inflow based on wavelet transform

In the third-generation nuclear power technologies , the non-uniform inflow at the pump inlet caused by the direct connection structure between the reactor coolant pump and the steam generator significantly impacts the pump's performance and internal flow , and may also induce additional vibration and noise, which in turn affects the pump's performance and structural integrity. In this paper, the flow complexity inside the reactor coolant pump under non-uniform inflow is analyzed by numerical simulation. The wavelet analysis method is used to compare the pressure pulsation characteristics and flow stability of reactor coolant pumps in both time and frequency domains. It is found that under non-uniform inflow conditions, the main characteristic signal waveforms tend to be chaotic and energy migrates to the main detail signals. Increased flow instability and pressure pulsations between the main flow path components were observed. Furthermore, the study reveals the main excitation frequency and harmonic components of the pressure pulsation. This study provides theoretical foundations and technical support for the design and optimization of reactor coolant pumps. • The research in-depth study of the internal flow characteristics of the reactor coolant pump under non-uniform inflow, especially the unsteady excitation characteristics and vortex structure evolution mechanism. • The wavelet analysis method is used to compare the pressure pulsation characteristics and flow stability of reactor coolant pumps in both time and frequency domains. • The research reveals the main excitation frequency and harmonic components of the pressure pulsation, which is crucial for controlling the internal flow excitation.