Numerical acoustic assessment of Krüger slat versus classic slotted slat | Innovative Design of Installed Airframe Components For Aircraft Noise Reduction

2024-06-30

Numerical acoustic assessment of Krüger slat versus classic slotted slat

High-lift device is a potent airframe noise contributor. The conventional slat, commonly used in a high-lift device, is known as one of the dominant noise sources. Krueger leading edge flaps (or slats) are of high interest in high-lift devices as they comply to the requirements of laminar wing technology and are said to be quieter than state-of-the-art slat systems.

This device was experimentally investigated by DLR in the German national research project INTONE led by Airbus. More specifically, aeroacoustic wind tunnel tests have been achieved at DNW/NWB on the Airbus 3DFNGY semispan high-lift model of scale 1:15.5.

The objective of the present task is to numerically investigate the noise benefit offered by Krueger devices with the help of Computational Fluid Dynamics (CFD) and Computational Aero-Acoustics (CAA) simulations. Two CFD approaches have been selected.

The first one, achieved by Chalmers, is a Navier-Stokes approach relying on an Improved Delayed Detached Eddy Simulation (IDDES) with the Spalart-Allmaras (S-A) model. The second one, achieved by ONERA, is a lattice-Boltzmann approach relying on a wall-model Large Eddy Simulation (LES). For both approaches, CAA relies on the Ffowcs-Williams and Hawkings (FWH) surface integration from collected CFD data. To reduce the computational cost, a short span of the entire high-lift device is selected as the focusing region for scale-resolving and acoustic computations.

Three high-lift configurations have been selected from the INTONE experimental database to be addressed by CFD/CAA simulations: (i) the slat reference configuration, (ii) the Krueger1 configuration and (iii) the Krueger19t configuration which experimentally showed a significant noise benefit. Both aerodynamic and aeroacoustic performances of the Krueger high-lift devices are investigated in comparison to the conventional slat configuration.