Influence of Porous Inserts and Compact Resonators on Onset of Taconis Oscillations

Abstract Taconis oscillations represent excitation of acoustic modes due to large thermal gradients inside narrow tubes penetrating cryogenic vessels from a warm ambient environment. These oscillations are usually harmful, as they may drastically increase heat leakage into cryogenic vessels and result in strong vibrations of measuring instruments. Placing a porous material inside a tube with a goal to increase acoustic damping or attaching a small resonator to the main tube are some of the possible ways to suppress or mitigate Taconis effects. However, when the porous inserts are positioned in locations with large temperature gradients or the resonator parameters are selected incorrectly, these components may augment thermal-to-acoustic energy conversion and enhance Taconis oscillations. A low-amplitude thermoacoustic model has been extended and applied in this study to determine the effects of the insert location and pore radius, as well as the resonator dimensions, on the onset of Taconis phenomena in a hydrogen-filled tube of relevance to lines used in cryogenic hydrogen storage tanks. The presented findings can assist cryogenic specialists interested in suppressing or exciting Taconis oscillations.