Freestream Noise in the Purdue University Boeing/AFOSR Mach-6 Quiet Tunnel
Derek Mamrol, Joseph S. Jewell
Abstract
View Video Presentation: https://doi.org/10.2514/6.2022-2453.vid The ambient pressure fluctuations within a wind tunnel test environment can severely affect the boundary layer transition observed on test articles. The Boeing/AFOSR Mach 6 Quiet Tunnel was designed to minimize these fluctuations, also referred to as noise, and is the world’s premier facility for studying hypersonic boundary layer transition in a quiet flow environment. All experiments performed for this work were conducted at this facility. The freestream flow field of this tunnel has been characterized multiple times since its creation, however an extensive three-dimensional spatial sweep has never been conducted. A pitot rake model was designed to allow for an extensive spatial survey of tunnel noise. This model created measurement capabilities that were previously unknown to the BAM6QT facility, including the ability to take multiple concurrent freestream pitot probe measurements. This new measurement apparatus was used to investigate the effect that cavities in the tunnel wall created by the installation of new optical windows had on the freestream noise level. The experiments conducted provide evidence that the tunnel wall cavities do increase the noise downstream of their location by approximately 100%, however a control dataset is needed to verify this finding.