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Experimental analysis of the flow over an oscillating airfoil and its acoustic radiation

Post-Doc position
24 months

There are many applications where it is important to predict the broadband noise radiated by an airfoil, either in air (fan, turbofan aeroengines, wind turbines) or in water (marine propellers, hydrokinetic turbines). The goal of the AEROAC project is to characterize experimentally the broadband airfoil noise in static (fixed angle of attack) and dynamic (oscillating airfoil) configurations. We are interested both in noise generation mechanisms at low incidence (trailing edge noise and turbulent inflow noise) and at larger incidence (separation and stall noise).

In the framework of this project, we will characterized the cyclic variations of trailing edge noise and dynamic stall noise in a controlled environment using an original experimental setup, made of an airfoil in forced oscillating motion. This setup will be installed first in the IMSIA wind tunnel to perform aerodynamic studies: force measurement with a 6-component force and torque sensor, low frequency (≈ 200 Hz) wall pressure
measurement using a pressure scanner, flow visualization around the airfoil using a PIV system. Then, the setup will be installed in the LMFA anechoic chamber to realize coupled aerodynamic and acoustic measurement: high frequency (> 10 kHz) wall pressure measurement using remote microphone probes, far-field acoustic pressure using a microphone array.

The originality of this experimental database is to characterize in a detailed way the flow around the airfoil and the airfoil noise radiated in dynamic configurations. It will be useful to better understand the physical mechanisms responsible for the noise on the one hand, and to test the models proposed in the literature on the other hand.

The objectives of this post-doctoral position are:
• to finalize the design of the experimental setup and to realize the aerodynamic and acoustic measurements in the IMSIA and LMFA wind tunnels;
• to analyze the influence of various parameters (Reynolds number, inflow turbulent rate, confinement effects) on separation and stall phenomenons in static and dynamic configurations, and to propose an adjustment method to compare measurements from the two facilities;
• to compare the far-field acoustic pressure calculated using analytical models (Amiet, Howe) and/or hybrid numerical methods (based on Code Saturne simulations) developed in the lab to the measurements.

2/28/19 12:00 AM
PDF document Postdoc_AEROAC_en.pdf — PDF document, 1.67 MB

http://perso.ensta-paristech.fr/~cotte/wordpress/?page_id=31

Benjamin Cotté

benjamin.cotte@ensta.fr