Thermoacoustic instabilities in a Rijke tube with heating and cooling elements

Thermoacoustic instabilities are investigated in a Rijke tube with both heating and cooling elements. The effects of the time delays of the elements, magnitudes of the temperature jumps, and location and compactness of the cooling element are investigated. The results show that for small temperature jumps, the system behaves periodically with changing source time delay. However, for larger temperature jumps corresponding to realistic combustion systems, various stable and unstable situations can occur, which simultaneously depend on the source and sink time delays. This dependence in some configurations is to the extent that the system is predicted unstable or stable, depending on whether or not the heat exchanger is included. In addition, the location or compactness of the heat sink has opposing effects depending on the source time delay. This investigation shows that a correct prediction of the system stability requires taking into account the coupled effects of the heat source and sink. An extension of this verified model can be used to predict instabilities in full-scale domestic heating systems