Definition of heater location to drive maximum amplitude acoustic oscillations in a Rijke tube

Abstract This paper presents an analysis that defines the heater location to drive maximum amplitude acoustic oscillations in a Rijke tube. The analysis is based on the mathematical formulation of the Rayleigh criterion and, although applied to a simple geometry, it can be extended to investigate driving in geometries for which the acoustic characteristics are known. For a Rijke tube of length L, driven by a combustion process, it was calculated theoretically that maximum amplitude oscillations occur for the heater bed located at a) L 4 for the fundamental mode; b) L 8 and 5L 8 for the second harmonic; and c) L 12 , 5L 12 , and 3L 4 for the third harmonic, where the distances are measured from the bottom of the tube. These results were checked experimentally, using a basket of burning wood, for the sections L 4 , L 8 , 5L 8 , and L 12 . It was verified that acoustic oscillations can be excited in a Rijke tube with its heater element located in certain positions in the upper half.