Investigation on the unsteady pressure pulsations and related vortical structures in a molten salt pump

Abstract

Abstract The high‐temperature molten salt pump (MSP) is the core equipment of the thermal storage system for concentrating solar power plants, which circulates the molten salt of the thermal storage medium. This study employs numerical simulation of a two‐stage MSP with a storage tank to find the correlation between pressure pulsations and the evolutions of vortical structures based on renormalization group k‐ε turbulence model. It is shown that rotor/stator interaction is the most significant excitation source of pressure pulsations with the prominent excitations being the diffuser passing frequency (fDPF) in the impeller and the blade passing frequency (fBPF). Furthermore, Q‐criterion is employed to capture the periodic shedding vortexes with a frequency of about 3fR at the suction surface and the trailing edge in diffusers. Impinging vortex and shedding vortex with the frequency 6fR on the leading edge of the diffuser is captured. The vortex shedding characteristics are significantly different under various conditions, and the separation vortexes appear at the leading edge of pressure surface in the diffusers at higher flow rates. Finally, it is obvious that the excited components and their magnitudes in the pressure spectrum are closely associated with the unsteady vortical structures within the model pump.

Keywords

• molten salt pump
• pressure pulsations
• rotor/stator interaction
• vortical structures