The dynamic characteristics in the wake systems of a propeller operating under different loading conditions

Improved delayed detached-eddy simulations (IDDES) on the computational domain composed of 48 million cells were employed to numerically simulate the propeller wake with various advance coefficients, shedding light on the dynamic characteristics and the evolution mechanisms for the entire wake system subject to different loading conditions. Validation against available experimental data under open water configuration was conducted to verify the numerical modelling in the present work. Dynamic mode decomposition, or to be more specific, its sparisity promoting varient, was further adopted to capture the fundamental spatiotemporal scales of the propeller wakes. The results of the simulation revealed that the low streamwise convection velocity with the high advance coefficient suppresses the wake vortex transportation, resulting in a helicoidal tip vortex system with strong interference effects and low pitch that leads to the earlier occurrence of propeller wake instability. The wake systems with high advance coefficient better maintain the memory of propeller rotation, resulting in more coherent downstream wakes. Moreover, the different interaction modes leading to wake instability were discussed.