PIV-Based Hydrodynamic Analysis of a 2D Lifting Body Using Near-Field Flow Kinematics

The ability to extract quantitative flow information from photographic images of the velocity field using Particle Image Velocimetry (PIV) is a powerful alternative to the more traditional invasive or integrated method techniques. The usage of PIV allows the complete characterization of the flow field, and not just at discrete points. Additionally, with PIV, it is possible to predict the hydrodynamic characteristics of a lifting body without measuring the forces and moments acting upon it. In this paper, the hydrodynamic performance of a NACA 0018 airfoil was determined by analyzing the flow kinematics from a 2D-2C (two-dimensional, two-component) PIV data set. The motivation for this work was to provide a canonical study to show that laser optical measurement techniques such as PIV, can be an attractive alternative to dynamic force testing. The hydrodynamic performance evaluated using PIV data was compared to the computational program XFOIL to assess the validity of the results. The analytical drag force prediction was carried out using the Von Kármán Momentum Integral approach for a flat plate and the Squire-Young boundary layer method as an improved method, whereas the analytical lift force prediction calculation was based on the Kutta-Joukowski theorem. The results show reasonable agreement with the numerical prediction tool XFOIL and they follow the expected trends across all operating conditions. These findings suggest that this methodology might be expanded to conduct hydrodynamic analyses on more complex geometries such as hydrofoils, turbines, propulsors, fin stabilizers, rudders, and other control surfaces using flow kinematics data from PIV.