Analysis of Coherent Structures in Large-Eddy Simulations of a NACA0012 Airfoil

Author(s)

Ricciardi, Tulio Rodarte ; Marques Ribeiro, Jean Helder ; Wolf, William Roberto

• Document type: Journal article
• Source: AIAA SCITECH 2019 FORUM; v. N/A, p. 14-pg., 2019-01-01.

Abstract

Coherent structures in a turbulent flow past a NACA0012 airfoil are investigated using different proper orthogonal decomposition techniques. Here, we employ the filtered POD and the frequency domain POD to characterize the dynamics of the most energetic coherent structures and relate them to tonal noise radiation. The present study is performed using a LES database of an airfoil flow obtained for Reynolds number Re-c = 408000 based on the airfoil chord. The freestream Mach number considered in the simulation is M-infinity = 0.115 and the angle of incidence is 5 deg. A study of different POD norms and reconstructions for different regions of the computational domain is presented. It is shown that low frequency u velocity fluctuations dominate the spectra of POD temporal modes for a norm based on turbulent kinetic energy. On the other hand, when the modal analysis is performed using a v velocity norm, one can see the presence of spanwise aligned two-dimensional coherent structures along the airfoil wake and which are related to the tonal noise generation. These structures are shown to be related to a laminar boundary layer forming on the pressure side of the airfoil. Different tripping setups for transition are tested and their impact on coherent structures formed on the suction side is also presented. (AU)

• FAPESP's process: 13/03413-4 - Investigation of noise generation and propagation by aerodynamic configurations using computational aeroacoustics
• Grantee: William Roberto Wolf
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 13/07375-0 - CeMEAI - Center for Mathematical Sciences Applied to Industry
• Grantee: Francisco Louzada Neto
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 18/19070-2 - AIAA Science and Technology Fórum 2019 (SciTech 2019)
• Grantee: William Roberto Wolf
• Support Opportunities: Research Grants - Meeting - Abroad