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This paper is the first part of a series of papers on results obtained in the EXEJET project. EXEJET was a French government-funded program started in 2008 and concluded in 2013, involving 3 partners: Airbus, Onera, Snecma. The project aimed at improving understanding and tools to assess and reduce installed jet noise for modern airliners. Project highlights are the following: Airbus designed and manufactured a swept wing model specifically for wind-tunnel tests at the anechoic facility CEPRA19 -Snecma conceived a large BPR-9 scaled nozzle model with a range of chevron shapes and validated the design methodology -A high-quality experimental flow and noise database was acquired in wind tunnel -Different simulation methods were benchmarked upon this new data. The installation effects of the nozzle under wing are then subject of focus. Significant aeroacoustic installation effect were measured by wing-mounted unsteady pressure sensors, far-field microphones and by Onera three-dimensional source localization array. In the far field, the new wing generated significantly lower levels of background noise in the tunnel compared to previous experience. The installation effects were typically dominant in the low frequency range of jet noise and in the forward arc. Phased array techniques were able to characterize the acoustic installation effects in two dimensions, and quantify them by projection to the far field. In the near field of the powerplant, the unsteady pressure measurements on the wing under-side surface revealed large-scale fluctuations imposed by the jet and spatially coherent. In spite of the presence of pylon and wing, these wavepacket signatures were found qualitatively similar to previous measurements made on coaxial jets from simpler axi-symmetric nozzle. Thanks to the high degree of collaboration between the three partners, EXEJET represents a step beyond the previous common VITAL WP7.2 investigations. The EXEJET database provides a foundation for analysis and validation of future modeling and numerical simulation aiming at quantifying installed jets aeroacoustics. Nomenclature BP RBy-Pass Ratio of an Engine or Nozzle: mass flow ratio between secondary (fan) over primary (core) D mixMixed (or Equivalent) jet diameter (m) JF I Jet-Flap Interaction JW I Jet-Wing Interaction M a Mach number of the flight stream N P R Nozzle Pressure Ratio: total pressure at exhaust over ambient pressure OASP L Overall Sound Pressure Level (dB) OP Operating Point in the test matrix P IV Particle Image Velocimetry SP L Sound Pressure Level (dB) SN R Signal-to-Noise Ratio St Strouhal number T KE Turbulent Kinetic Energy V mix Mixed jet velocity (m/s)Flight stream velocity V P Primary jet exhaust velocity V S Secondary jet exhaust velocity Ψ Polar angle relative to inlet axis Θ Azimuthal angle relative to pylon (180 deg is flyover direction, opposite to the pylon and toward the ground) Dissipation rateThe data analysis presents characteristic distances and velocities in terms of the equivalent mixed jet to allow a better compar...

This paper focuses on the numerical and experimental characterization of the vortex structures that develop along a simplified geometry of a wing equipped with pylon-mounted engine at low speed/high angle of attack flight conditions. In these conditions, the presence of the engine installation under the wing induces a complex and unsteady vortical flow field at the nacelle/pylon/wing junctions which interacts with the upper wing boundary layer and leads to a drop of aircraft performances. In order to gain insight into the physics driving this interaction, it is proposed to isolate its fundamental mechanisms by simplifying the problem. The parameters of interest that led to the simplification of the model are first described. As a first step into a more comprehensive knowledge of this complex physics, this study is initially conducted at a Reynolds number of 200000, based on the chord wing and on the free stream velocity. Two configurations of angle of attack and sideslip angles (α = 8°/β = 0° and α = 8°/β = 30°) have been investigated. This work relies on unsteady RANS computations, oil flow visualizations and 3C-PIV measurements. The vortex dynamics thus produced is described in terms of vortex core position, intensity, size and turbulent intensity thanks to a vortex tracking post-processing algorithm. In addition, the analysis of the velocity flow field obtained from the PIV measurements will highlight the influence of the longitudinal vortex issued from the pylon/wing junction on the separation process of the boundary layer near the upper wing leading-edge.

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A possible solution to improve the aircraft efficiency for the next decades is the use of boundary-layer ingestion engines. One of the industrial challenges linked to this type of engines is the aerodynamic distortion at engine intake. This work proposes to evaluate the characterization capability of several distortion indices, currently used in the industry, on a boundary layer ingestion engine configuration. The analysis is performed using several Reynolds-Averaged Navier-Stokes simulations. First, steady simulations of a simplified boundary-layer ingestion air intake are performed for off-design conditions. The principal distortion indices used in the industry are calculated for each flow solution. The results are discussed to assess their potential to highlight physical phenomena present in this configuration. Finally, this analysis allows identifying the weaknesses of the current distortion indices and to propose ways of improvement for new distortion indices more adequate for boundary layer ingestion configurations.