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Measurement and Analysis of Unsteady Surface Pressure During Turbulence-Airfoil Interaction

Year: 2025

Type: article

Abstract: The interaction of turbulence with an airfoil is a classical problem in aeroacoustics that is both scientifically and practically important. This paper is concerned with the measurement and understanding of how homogeneous, isotropic turbulence interacts with an airfoil and creates unsteady pressure on its surface. The paper presents new unsteady surface pressure measurements on a NACA 0012 airfoil placed in grid turbulence at multiple angles of attack (0−10 degrees). A new analysis framework and statistical modelling approach were used to study the pressure jump response. Root-mean-square pressure levels are much higher towards the leading edge, indicating that the turbulence interaction pressure response is contained to the first 15-25% of the chord over all angles of attack tested. The pressure jump power spectral density shows a broadband ‘hump’ at lower streamwise wavenumbers followed by additional spectral content attributed to boundary layer growth. The pressure jump spectra compare reasonably well with Amiet’s theory; however, there are some differences that are attributed to flow distortion effects. The framework parameters show that the unsteady pressure levels are reasonably balanced across the airfoil during turbulence interaction but there are significant changes in the coherence and phase between the suction and pressure sides. At zero angle of attack, it was found that the airfoil’s local pressure response broke down when the airfoil thickness was about a third of the streamwise convective wavelength. At angles of attack, the phase response was explained in terms of the distortion of eddies as they encounter the leading edge and are subsequently convected by the flow on each side of the airfoil. Coherence was shown to decay exponentially with both chordwise position and angle of attack, and models are proposed to consider these effects. It is hoped that these results can provide new insights into turbulence-airfoil interaction physics, be used to validate more sophisticated distortion models and eventually improve the prediction of airfoil leading edge noise.

Source: AIAA Journal

DOI: 10.2514/1.j066488

Authors: Con Doolan, Roman Kisler, Chaoyang Jiang, Charitha de Silva, Danielle Moreau

Institution: UNSW Sydney

Language: English

Topic: Aerodynamics and Acoustics in Jet Flows

Subfield: Aerospace Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: green

Funder: Australian Research Council

Award: Understanding and predicting airfoil noise in real-world turbulence