Blade-notch-induced vortex cascades and multiscale turbulence modulation in propeller wakes

An improved delayed detached-eddy simulation was performed on a marine propeller with notched blades using an unstructured grid consisting of 52.5 × 106 cells. This study focuses on further revealing the mechanisms by which different numbers of notched blades influence wake instability. The results show that an increase in the number of notches intensifies the mutual inductance effect and accelerates wake instability, which significantly alters the momentum transfer process and the anisotropy of turbulence in the wake. The earlier turbulence diffusion and mixing lead to a more isotropic state in the far-field wake. The study emphasizes the specific processes of kinetic energy transport and generation in the wake to analyze the role of notch numbers in wake coherence, quantifying the impact of wake instability caused by different notch configurations on the kinetic energy transport process. Increasing the number of notches leads to a more pronounced wake instability, which reduces turbulence generation and lowers the turbulence levels in the wake.