A generic computational study of broadband high-lift noise generation for simplified slat and flap problems

Abstract

In previous work a RANS based simulation technique for the simulation of broadband slat noise was established. The computational approach is based on acoustic perturbation equations forced by stochastic sound sources to simulate sound generation and radiation in space and time. Good agreement was found between predicted and measured slat noise spectra and for trailing edge noise generated at a NACA 0012 airfoil. In this work the simulation approach is applied to generic high-lift noise problems defined in the framework of the European project VALIANT. The problems considered are sound generation at the slat and the flap of simplified high-lift geometries. Results of the time-averaged mean flow and turbulence statistics from RANS are evaluated and compared to measurements. A comparison of the statistics of the stochastic fluctuations with flow data is provided. Acoustic sound generated by the stochastic source model is evaluated and compared to measurements. As a general outcome of the study, the agreement between the RANS flow fields to measurements is quite good. The reconstruction of the turbulence statistic by FRPM is in general accurate, but in some reagions it differes from the target statistic. The agreement of the acoustic far field predictions to the measured data is satisfying. The overall procedure is with a computational effort of around two days quite short.

Prediction of Porous Trailing Edge Noise Reduction via Acoustic Perturbation Equations and Volume Averaging

“…The hybrid approach takes the time-averaged flow data and turbulence statistics from steady a Reynolds Averaged Navier-Stokes (RANS) simulation to model synthetic vortex sound sources and predict the aeroacoustic sound generation and radiation in space and time by means of Code for Computational Aeroacoustics (CAA). The CFD/CAA was applied in the past to different airframe [18][19][20][21][22] and jet noise [23][24][25][26][27][28] problems and was successfully used in the BANC III benchmark workshop 29,30 for the validation of NACA0012 trailing edge noise against measurements.…”