Design and evaluation of an aeroacoustic wind tunnel for measurement of axial flow fans

Abstract

An anechoic wind tunnel dedicated to fan self-noise studies has been designed and constructed at the von Karman Institute The multi-chamber, mass flow driven design allows for all fan performance characteristics, aerodynamic quantities (e.g., wake turbulence measurements), and acoustic properties to be assessed in the same facility with the same conditions. The acoustic chamber performance is assessed using the optimum reference method and found to be within the ISO 3745 standards down to 150 Hz for pure tone and broadband source mechanisms. The additional influence of installation effects of an aerodynamic inlet was found to create a scattered sound field only near the source location, while still providing good anechoic results at more distant sound pressure measurement positions. It was found to have inflow properties, span-wise uniformity, and low turbulence intensity, consistent with those desired for fan self-noise studies.

Design of a low-noise aeroacoustic wind tunnel facility at Brunel University

“…Similarly, low background noise is reported and many airfoil self noise studies have been carried out using this facility 14,15 . There are also other university-based aeroacoustic wind tunnels, for example in refs [16][17][18] , which have been built for different purposes.…”

Influence of Swept Blades on Low-Order Acoustic Prediction for Axial Fans

“…The cooling module has been mounted in the ALCOVES anechoic chamber in an open-rotor configuration, as depicted in Figure 2a, and its far-field sound spectrum has been measured for the fan nominal working condition at one-meter distance, aligned with the center of the fan. The laboratory has been designed by Bilka et al [26] to have low turbulence level at the inlet and an acoustic cut-off frequency of 150 Hz. The chosen fan has 7-unequally-spaced blades that are forward skewed, with high sweep-angle values particularly at the tip of the blades.…”

Sound localization and quantification analysis of an automotive engine cooling module

“…The VKI experimental measurements are carried out in the ALCOVES anechoic laboratory, where aerodynamic and aeroacoustic measurements can be conducted simultaneously. This testing facility is characterized by a cut-off frequency of 200 Hz [42] and composed of two anechoic rooms separated by a modular wall partition that can accommodate different components such as automotive cooling systems [40] and ducted fans [43]. The flow inside the wind tunnel is driven by an auxiliary fan placed in a downstream circuit, generating a pressure difference across the rooms.…”