Trailing edge noise reduction using bio-inspired finlets

PeerReviewe

3.7. : Aeroacoustic investigation of a circulation controlled high-lift flap by overset-LES

The Council of European Aerospace Societies (CEAS) Aeroacoustics Specialists Committee (ASC) supports and promotes the interests of the scientific and industrial aeroacoustics community on a European scale and European aeronautics activities internationally. In this context, “aeroacoustics” encompasses all aerospace acoustics and related areas. Each year the committee highlights some of the research and development projects in Europe. Due the effects of the Covid 19 pandemic it was not possible to publish an edition in 2021 and so this paper is a report on highlights of aeroacoustics research in Europe in both 2020 and 2021, compiled from information provided to the ASC of the CEAS. In addition, during 2020 and 2021, a number of research programmes involving aeroacoustics were funded by the European Commission. Some of the highlights from these programmes are also summarized in this article. Enquiries concerning all contributions should be addressed to the authors who are given at the end of each subsection.PeerReviewe

Trailing-edge noise reduction of a wing by a surface modification

There is an increased emphasis on reducing airframe noise in the last decades. Airframe noise is sound generated by the interaction of a turbulent flow with the aircraft geometry, and significantly contributes to the overall noise production during the landing phase. One examples of airframe noise is the noise generated at a wing's trailing edge, i.e., trailing-edge noise. In this contribution, we numerically explore the local application of riblets for the purpose of trailing-edge noise reduction. Two configurations are studied: i) a clean NACA0012 wing section as a reference, and ii) the same configuration with riblets installed at the wing's aft part. The numerical investigation follows a hybrid computational aeroacoustics approach, where the time-average flow is studied by means of RANS. Noise sources are generated by means of a stochastic approach called Fast Random Particle Mesh method. The results show a deceleration of the flow behind the riblets. Furthermore, the turbulent kinetic energy indicates increased unsteadiness behind the riblets which is shifted away from the wall due to the presence of the riblets. Lastly, the sound sources are investigated by means of the 3D Lamb-vector, which indicates a slight reduction in magnitude near the trailing edge

From CAA to CFD

In this contribution, an application of a computational aeroacoustic code as a hybrid Zonal LES tool is presented. The here used hybrid approach is based on a novel implementation of the Non-Linear Perturbation Equations extended with fluctuating viscous terms, denoted as “Overset” since a perturbation analysis is performed on top of a background flow. The extension to LES is demonstrated with isotropic decaying turbulence, where the expected temporal decay and scaling of the reference DNS data is recovered with the LES employing a classical Smagorinsky model. Furthermore, a conceptual approach is presented that describes the investigation of sound sources with application to trailing-edge noise.Deutsche Forschungsgemeinschaf

Automotive on-road flow quantification with a large scale Stereo-PIV set-up

In this work on-road flow measurement for automotive demands is implemented by means of a large-scale stereoscopic PIV, which was introduced by Sciacchitano et al. (2015) under the name Ring of Fire. In this work the whole wake region was investigated with a stereo camera configuration. The test vehicle was a Volkswagen up! traveling at a speed of 33.33 m/s, resulting in a Reynolds number of 3.30 x 106 based on the vehicle height. Measurements were acquired at a rate of 6 kHz with a measurement plane of approximately 2.8 x 2.2 m2. Time-resolved data was processed by means of cross correlation and the Shake-The-Box approach. Resulting non-dimensional, ensemble-averaged streamwise velocity fields of the wake compare well to literature and show that the on-road flow topologies of the wake can be resolved by both approaches.PeerReviewe

Reacting Fronts in Random Environments

In the present short paper we derive and discuss an evolution equation for an observable related to the propagation of reacting fronts into random environments, that can be understood as the effective volume of the reacted mixture fraction. This evolution equation was previously derived by some of us but with different point of views because focused on the different applications. Here, after to have remarked that the contourn provided by the mean motion of the interface particles is different from the mean of the random contourns, we try to figure out as the proposed equation can be useful to provide in the future a relationship between these two different descriptions

2.12. : An acoustic relaxation term for damping and forcing of waves

The Council of European Aerospace Societies (CEAS) Aeroacoustics Specialists Committee (ASC) supports and promotes the interests of the scientific and industrial aeroacoustics community on a European scale and European aeronautics activities internationally. In this context, “aeroacoustics” encompasses all aerospace acoustics and related areas. Each year the committee highlights some of the research and development projects in Europe. Due the effects of the Covid 19 pandemic it was not possible to publish an edition in 2021 and so this paper is a report on highlights of aeroacoustics research in Europe in both 2020 and 2021, compiled from information provided to the ASC of the CEAS. In addition, during 2020 and 2021, a number of research programmes involving aeroacoustics were funded by the European Commission. Some of the highlights from these programmes are also summarized in this article. Enquiries concerning all contributions should be addressed to the authors who are given at the end of each subsection.PeerReviewe

Reaction-Diffusion Equation and G-Equation Approaches Reconciled in Turbulent Premixed Combustion Modelling

Stochastic fluctuations described by an adequate probability density function are imposed to the average flame position in order to give a proper formulation of the flame surface propagation in turbulent premixed combustion. An evolution equation of reaction-difffusion type is derived for an observable that can be understood as the effective burned fraction. When stochastic fluctuations are removed, the G-equation along the motion of the mean flame position is recovered suggesting that approaches based on reaction-diffusion equations and G-equation are indeed complementary and they can be reconciled. Moreover, when a plane front is assumed, the Zimont & Lipatnikov model is recovered. This last result suggests that the proposed equation can be considered as the natural extension of the Zimont & Lipatnikov model to the case with non null mean curvature

Recent Progress in Trailing-Edge Noise Computations with Overset LES

Deutsche Forschungsgemeinschaf