Improved Delayed Detached Eddy Simulation modeling and far-field trailing-edge noise estimation of a sharp-edged symmetric strut

Abstract

This paper presents results of a Computational Fluid Dynamic (CFD) study of a sharp-edged symmetric flat strut at Reynolds number 500,000 based on chord at zero degrees angle of attack, and the subsequent estimation of far-field noise generated at the trailing-edge. Flow field results obtained using Improved Delayed Detached Eddy Simulation (IDDES) modelling and Reynolds-Averaged Navier Stokes (RANS) modelling techniques are compared with empirical wind-tunnel data. The flow is observed to be physically complex in nature, exhibiting numerical solutions that are sensitive to the mesh grid and freestream turbulence intensity. Although originally developed for use specifically with RANS-generated flow data, the RANS-based Statistical Noise Model (RSNM) technique, which estimates far-field noise from mean turbulence data via an acoustic Green's function and a statistical turbulence correlation model, is used here to estimate far-field noise spectra from both RANS and IDDES flow data. Far-field noise is also estimated from the IDDES model using the permeable surface form of the Ffowcs Williams and Hawkings (FWH) solver. The FWH estimate gives the closest match to experimental data, while the RSNM-generated noise estimate from the IDDES data appears to be more successful at capturing the large turbulent structures within the flow than the RANS data.