Gas Flow Mapping in a Recorder: An Application of SPRITE MRI

Abstract

The study of gas flow characteristics in wind instruments, specifically recorders, presents a challenge. Most currently available techniques are invasive, and computational fluid dynamics (CFD) simulations must be relied upon. In this paper, a magnetic resonance imaging (MRI) technique is presented that is non-invasive and non-destructive, and offers quantitative results that can be used to better understand gas flow in a recorder. In particular, 3-D MRI measurements of the velocity field in a real playing recorder are presented. A divergence map and maps of the correlation coefficient (\(R^2\)) are presented alongside the velocity maps as a tools for validation. A log ratio of signal amplitudes is also mapped to indicate regions with larger turbulent fluctuations. This methodology affords a useful tool for the validation of CFD simulations for the study of wind instruments.