Characterizing rotating cavitation in liquefied natural gas in submerged pumps

The shipping industry is transitioning from heavy fuel oil to liquefied natural gas (LNG) to meet environmental regulations. Submerged LNG pumps, however, are prone to catastrophic failure due to the formation of small vapor-filled cavities in the liquid gas, in a process called cavitation. One form, called rotating cavitation, remains poorly understood, and occurs when cavitation patterns propagate between pump blades.

Xu et al. characterized the rotating cavitation pressure pulsation and propagation characteristics in a three-bladed submerged pump inducer with numerical simulations. Combining turbulence and cavitation models and validating the result against experimental data, they found that rotating cavitation occurs through systematic inter-blade interactions rather than independent blade behavior.

“The validated numerical framework allows reliable prediction during design phases, preventing costly marine equipment failures,” said author Bin Xu. “The frequency shift mechanism provides new diagnostic tools for identifying rotating cavitation onset. For LNG transportation, this supports reliable pump designs essential for marine decarbonization.”

Previous standard models of cavitation and turbulence required specialized density corrections because they often overestimate turbulent effects in cavitating flows.

Their findings demonstrated that cavitation on one blade creates predictable propagation by generating vortical disturbances that modify flow angles at adjacent blades, which in turn produces characteristic frequency shifts from blade-passing to shaft frequency as cavitation intensifies.

Increasing the likelihood of cavitation leads to a drop in the inducer’s performance, driven by a backward expansion in the cavitation area in the inducer.

The group next looks to experimentally validate its model using high-speed visualization and synchronized pressure measurements to confirm the predicted inter-blade interactions. They hope to see their work applied to rocket turbopumps, industrial pumps, and hydroelectric turbines.

Source: “Numerical investigation of rotating cavitation pressure pulsation and propagation characteristics in a three-bladed submerged pump inducer,” by Bin Xu, Xingyu Liu, Cong Shao, Xi Shen, Desheng Zhang, Yilin Deng, and B. P. M (Bart) van Esch, International Journal of Fluid Engineering (2025). The article can be accessed at https://doi.org/10.1063/5.0271134 .