Study of Thermoacoustic Phenomenon in a Rijke Tube

Thermoacoustics is concerned with the interactions between heat (thermo) and pressure oscillations in gases (acoustics). A “Rijke Tube”, named after its inventor, is a fundamental tool for studying thermoacoustic phenomenon. Rijke's tube turns heat into sound, by creating a self-amplifying standing wave. It is basically an open-ended tube with a properly placed heat source inside. To study the phenomenon a Rijke tube apparatus was designed and constructed with the facility to change the heat source position and the heat input of the source. Experiments were conducted by changing the heat input, the tube length and diameter. Effects of these parameters on the output sound level were studied. The heat source position was changed and the sound level was measured to estimate the optimal position of the heat source in Rijke tube and to compare it with Rayleigh's estimation. The input electrical power consumed by the heater and the output sound power was calculated. The conversion efficiency of sound power from heat input was calculated and found to be minimal. The focus of this paper is to quantitatively evaluate the performance of the apparatus designed and to explain the mechanism of thermoacoustic phenomenon in Rijke tube with the help of ‘Rayleigh's criterion’.