Investigation of Wake Dynamics of a Slender Symmetric Trailing Edge Hydrofoil

TL;DR

This study combines high-resolution LES simulations with PIV measurements to analyze the wake dynamics of a slender symmetric hydrofoil, providing insights into vortex shedding and wake structures at high Reynolds numbers.

Contribution

It introduces an integrated approach using LES and PIV with POD analysis to accurately characterize turbulent wake structures of hydrofoils at high Reynolds numbers.

Findings

POD reveals energy distribution across multiple wake modes.

Leading POD mode captures primary wake dynamics.

LES and PIV data show strong agreement in wake reconstruction.

Abstract

Accurate prediction of wake dynamics behind hydrofoils is critical for mitigating vortex-induced vibrations and improving the performance of hydraulic machinery. Conventional turbulence modeling approaches often struggle to capture the unsteady, coherent structures governing wake behavior, particularly for slender hydrofoils operating at high Reynolds numbers. This study addresses this limitation by combining scale-resolving numerical simulations, including high-resolution Large Eddy Simulation (LES), with Particle Image Velocimetry (PIV) measurements to investigate the turbulent wake of a symmetric, blunt trailing-edge hydrofoil operating at zero angle of attack. The flow was analyzed at a Reynolds number of approximately 7.5x10e5, i.e. close to the onset of wake-structure interaction effects. LES was performed using a fine mesh of approximately 500 million nodes to resolve near-wall and wake dynamics beyond the experimental field of view, while PIV measurements provided time-resolved velocity fields downstream of the trailing edge. Proper Orthogonal Decomposition (POD) was applied to the PIV data to extract dominant coherent structures and quantify their contribution to the turbulent kinetic energy. POD analysis reveals that energy is distributed across many modes, with the leading mode capturing the primary wake dynamics and higher modes forming coupled oscillatory pairs associated with von Karman vortex shedding. PIV-LES agreement shows that central wake measurements combined with numerical simulations enables full wake reconstruction and validates modeling for vibration-relevant hydrofoil dynamics.