Airframe Noise Reduction Technologies Applied to High-Lift Devices of Future Green Regional Aircraft
Résumé
In the framework of CS-GRA ITD Project the acoustic impact of several high-lift devices (HLDs) and relevant low-noise technologies have been numerically and experimentally assessed toward their application to future regional aircraft for airframe noise reduction.
CIRA designed an innovative “lined” flap, conceived as multi-layer structure with micro-perforation on the external sheet. The design was performed through an evolutionary algorithm that drives a FEM model of the acoustic field supported by analytical/empirical models for trailing-edge noise source estimation and liner impedance parameterization. The optimization of constructive liner parameters provided maximum noise reduction of about 6 dB along a downward radiation arc. CIRA also designed and numerically assessed three types/sizes of flap side-edge fences.
Experimental investigations/validation of the above low-noise concepts were carried out through 2D WT tests at INCAS in collaboration with CIRA. Microphones array and the beam forming technique allowed assessing potential noise reduction of these technologies.
ONERA numerically assessed an optimal distribution of absorbing liners for slat noise reduction. The aeroacoustic analysis was obtained through a ZDES approach for noise sources computation and a FW-H solver for acoustic propagation. The study showed liners providing noise reduction up to 5 dB along a downward radiation arc. Liners characteristics were delivered by tests in a specific bench, taking into account grazing flow.
FOI and Chalmers carried out in project ALONOCO (CfP JTI-CS-2009-01-GRA-02-001) CFD/CAA 3D analyses of wing multi-body configurations with different HLDs. The aeroacoustic assessment was based on hybrid RANS-LES calculations for flow-induced noise generation and acoustic analogy methods for far-field noise propagation. Aerodynamic performance evaluation came from steady-state RANS solutions. Computations showed that configuration combining Krueger and flap gives best aerodynamic performance with maximum lift increasing of 20% and noise level reduced up to 10 dB, when compared at same lift coefficient, with respect to flap-only configurations.
FOI and Chalmers numerically assessed in project CALAS (CfP JTI-CS-2011-03-GRA-02-018) a flap side-edge fence on a three-component wing. The modeling of noise source was supported with a Stochastic Noise Generation and Radiation method based on RANS solutions, and the far-field noise level was predicted with a BEM solver. The analysis showed that the fence enables overall noise reduction of about 5-8 dB.
ONERA explored a multi-objective optimization of the slat position with respect to the main body of a conventional three-element wing configuration. The optimization approach, based on surrogate models, showed slat noise reduction of about 70% with aerodynamic performance also improved.
Domaines
Acoustique [physics.class-ph]
Origine : Fichiers produits par l'(les) auteur(s)
Loading...