Experimental Investigation of Bifurcations in a Thermoacoustic Engine
In this study, variation in the characteristics of the pressure oscillations in a thermoacoustic engine is explored as the input heat flux is varied. A bifurcation diagram is plotted to study the variation in the qualitative behavior of the acoustic oscillations as the input heat flux changes. At a...
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Series: | International Journal of Spray and Combustion Dynamics |
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doaj-700a725c984842c4a9fc08205e7ee6502020-11-25T03:40:52ZengSAGE PublishingInternational Journal of Spray and Combustion Dynamics1756-82771756-82852015-06-01710.1260/1756-8277.7.2.11310.1260_1756-8277.7.2.113Experimental Investigation of Bifurcations in a Thermoacoustic EngineVishnu R. Unni0Yogesh M. S. Prasaad1N. T. Ravi2S. Md Iqbal3Bala Pesala4R. I. Sujith5 Central Electronics Engineering Research Institute, Council of Scientific and Industrial Research Chennai-6000113, India Central Electronics Engineering Research Institute, Council of Scientific and Industrial Research Chennai-6000113, India Central Electronics Engineering Research Institute, Council of Scientific and Industrial Research Chennai-6000113, India Central Electronics Engineering Research Institute, Council of Scientific and Industrial Research Chennai-6000113, India Central Electronics Engineering Research Institute, Council of Scientific and Industrial Research Chennai-6000113, India Department of Aerospace Engineering, Indian Institute of Technology Madras Chennai-600036, IndiaIn this study, variation in the characteristics of the pressure oscillations in a thermoacoustic engine is explored as the input heat flux is varied. A bifurcation diagram is plotted to study the variation in the qualitative behavior of the acoustic oscillations as the input heat flux changes. At a critical input heat flux (60 Watt), the engine begins to produce acoustic oscillations in its fundamental longitudinal mode. As the input heat flux is increased, incommensurate frequencies appear in the power spectrum. The simultaneous presence of incommensurate frequencies results in quasiperiodic oscillations. On further increase of heat flux, the fundamental mode disappears and second mode oscillations are observed. These bifurcations in the characteristics of the pressure oscillations are the result of nonlinear interaction between multiple modes present in the thermoacoustic engine. Hysteresis in the bifurcation diagram suggests that the bifurcation is subcritical. Further, the qualitative analysis of different dynamic regimes is performed using nonlinear time series analysis. The physical reason for the observed nonlinear behavior is discussed. Suggestions to avert the variations in qualitative behavior of the pressure oscillations in thermoacoustic engines are also provided.https://doi.org/10.1260/1756-8277.7.2.113 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Vishnu R. Unni Yogesh M. S. Prasaad N. T. Ravi S. Md Iqbal Bala Pesala R. I. Sujith |
spellingShingle |
Vishnu R. Unni Yogesh M. S. Prasaad N. T. Ravi S. Md Iqbal Bala Pesala R. I. Sujith Experimental Investigation of Bifurcations in a Thermoacoustic Engine International Journal of Spray and Combustion Dynamics |
author_facet |
Vishnu R. Unni Yogesh M. S. Prasaad N. T. Ravi S. Md Iqbal Bala Pesala R. I. Sujith |
author_sort |
Vishnu R. Unni |
title |
Experimental Investigation of Bifurcations in a Thermoacoustic Engine |
title_short |
Experimental Investigation of Bifurcations in a Thermoacoustic Engine |
title_full |
Experimental Investigation of Bifurcations in a Thermoacoustic Engine |
title_fullStr |
Experimental Investigation of Bifurcations in a Thermoacoustic Engine |
title_full_unstemmed |
Experimental Investigation of Bifurcations in a Thermoacoustic Engine |
title_sort |
experimental investigation of bifurcations in a thermoacoustic engine |
publisher |
SAGE Publishing |
series |
International Journal of Spray and Combustion Dynamics |
issn |
1756-8277 1756-8285 |
publishDate |
2015-06-01 |
description |
In this study, variation in the characteristics of the pressure oscillations in a thermoacoustic engine is explored as the input heat flux is varied. A bifurcation diagram is plotted to study the variation in the qualitative behavior of the acoustic oscillations as the input heat flux changes. At a critical input heat flux (60 Watt), the engine begins to produce acoustic oscillations in its fundamental longitudinal mode. As the input heat flux is increased, incommensurate frequencies appear in the power spectrum. The simultaneous presence of incommensurate frequencies results in quasiperiodic oscillations. On further increase of heat flux, the fundamental mode disappears and second mode oscillations are observed. These bifurcations in the characteristics of the pressure oscillations are the result of nonlinear interaction between multiple modes present in the thermoacoustic engine. Hysteresis in the bifurcation diagram suggests that the bifurcation is subcritical. Further, the qualitative analysis of different dynamic regimes is performed using nonlinear time series analysis. The physical reason for the observed nonlinear behavior is discussed. Suggestions to avert the variations in qualitative behavior of the pressure oscillations in thermoacoustic engines are also provided. |
url |
https://doi.org/10.1260/1756-8277.7.2.113 |
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