Cross validation of the aerodynamic and acoustic measurements in two Kevlar-walled wind tunnels

Abstract

The wind tunnel with Kevlar walls is becoming more and more popular for aeroacoustic measurements, because the necessary corrections to convert aerodynamic coefficients to free field values are moderate and at the same time the signal to noise ratio of acoustic measurements are in the same order as in an open jet configuration. Yet, the technology is new and the correction methods for aerodynamic and acoustic coefficients are not well established. This paper aims on bench-marking two of the largest Kevlar-walled wind tunnels by cross validation of the measurements performed on a NACA633018 aerofoil model. The measured aerodynamic coefficients showed and excellent agreement in the attached flow regime. Maximum lift was predicted differently in the two facilities. The differences might be due to three-dimensional effects for separated flow and the fact that the aspect ration was different in the two facilities. The difference of the measured overall sound pressure levels was less ± 1 dB for attached flow conditions. However, we observed a difference in the slope of the sound pressure spectra and recommend to further investigate the acoustic correction methods.

AeroAcoustics.jl: A Julia package for aeroacoustics

“…AeroAcoustics.jl is the fast, entry-level open source software package, that fills the gap between the existing codebases available online. It has already been used in publications (Fischer et al, 2022(Fischer et al, , 2023Plaza et al, 2022), a PhD thesis (O. A.…”

Benchmarking of the NACA 633-018 Trailing-Edge Noise in a Broad Reynolds Number Range as Part of the IEA Task 39

“…The LRM was manufactured as an assembly of three solid modular aluminium structures. More details about the models may be found in [11,12]. The trailing edge thickness is 𝑡 𝑇 𝐸 = 7.5𝑐 × 10 −4 for both models.…”

“…DTU's Paul La Cour Tunnel measurements taken with Kevlar walls have been corrected using the methodology explained in Devenport et al [15,29], which is based on potential flow methods that take into account the wall presence including the flow transpiration through the Kevlar membranes. Details of this correction and a validation with Virginia Techical Unveristy can be found in the study of Fischer et al [12]. The different nature of these corrections is represented in the polar plots, since using XFOIL for the corrections leads to the results matching a pre-defined set of polars.…”