Abstract
In this work, we report thermodynamic cycle experienced by fluid parcels oscillating in a tube with a positive temperature gradient. Our experimental setup consists of a glass tube with a radius of 6.975 mm and a woofer speaker that is used to drive a gas column of atmospheric air filled in the tube at a frequency of 1.0 Hz. The non-dimensional parameter ωτ_α was below 10 in this experiment, which permits heat exchange between oscillating gas parcels and the tube wall. Lagrangian temperature and entropy associated with a given gas parcel were determined using the Eulerian pressure, velocity and temperature oscillations measured by experimental probes fixed in space. We show how the local energy conversion rate per unit time and volume changes with radial position, which verifies the thermodynamical approach to the understanding of thermoacoustic phenomena.
