Investigation on the vortex dynamics in the wake of a rotating propeller

Abstract

Improved Delayed Detached Eddy Simulation (IDDES) method on a 48 million grid is utilized to numerically simulate the E779A propeller wake, with a focus on comparing the evolution mechanisms and dynamics of wake topology instability under varying loading conditions. A tip vortex identification method is employed to extract and analyze the evolution trajectories along with the core positions of the tip vortices. Based on this, a Lumley map is established to visualize the development of the turbulence anisotropy at the tip and hub vortex cores. Detailed discussions of the turbulent energy spectra across various regions of the wake are also conducted. In addition, mode structures are analyzed using a reduced order strategy, emphasizing variations under different loading conditions. As tip vortices evolve downstream, the distorted and deformed trailing edge vortices undergo mutual induction with adjacent downstream tip vortices, signaling the onset of elliptical instability and the beginning of vortex system destabilization. Eventually, turbulence anisotropy gradually takes up in the vortex core. Similarity in the turbulence energy spectra can be observed under all loading conditions, in terms of both the energy injection scale and the inertial subrange. Additionally, mode decomposition results of reduced order modeling are examined, focusing on spatial flow patterns and characteristic temporal frequencies. The results show that the circumferential and radial deformation significantly contributes to vortex instability. The present paper aims to provide an insightful perspective and valuable reference for understanding the key mechanisms of propeller wake dynamics.