Boundary Layer Tripping Effects on Flow and Trailing-Edge Noise of a NACA 0012 Airfoil at Zero Angle of Attack

Abstract

The study presents a series of Wall-Modelled Large Eddy Simulations (WMLES) using the high-resolution GPU-accelerated CABARET method to investigate boundary layer tripping effects on a NACA 0012 airfoil. Simulations are performed at zero angle of attack for chord-based Reynolds numbers of 1.0 × 10⁶ and 1.5 × 10⁶, corresponding to the BANC III experimental conditions. For far-field noise prediction, the LES solutions are coupled with Amiet theory and the semi-empirical Brooks model. The numerical framework is validated against experimental data for pressure and skin friction coefficients, boundary layer flow and turbulence profiles, as well as wall pressure and far-field noise spectra. Having validated the baseline model, the trip geometry is systematically varied to evaluate its effect on the flow, turbulence, and pressure fluctuations in the boundary layer and the wake region around the trailing edge using statistical analyses, including Proper Orthogonal Decomposition and conditional averaging. Compared to the meanflow and turbulence details, the pressure fluctuations around the trailing edge are found to be insensitive to the trip parameters within the experimental error bar, indicating that the dominant coherent pressure structures responsible for noise scattering remain little affected by the upstream transition-triggering mechanism.