Capturing multifractality of pressure fluctuations in thermoacoustic systems using fractional-order derivatives
- The stable operation of a turbulent combustor is not completely silent; instead, there is a background of small amplitude aperiodic acoustic fluctuations known as combustion noise. Pressure fluctuations during this state of combustion noise are multifractal due to the presence of multiple temporal scales that contribute to its dynamics. However, existing models are unable to capture the multifractality in the pressure fluctuations. We conjecture an underlying fractional dynamics for the thermoacoustic system and obtain a fractional-order model for pressure fluctuations. The data from this model has remarkable visual similarity to the experimental data and also has a wide multifractal spectrum during the state of combustion noise. Quantitative similarity with the experimental data in terms of the Hurst exponent and the multifractal spectrum is observed during the state of combustion noise. This model is also able to produce pressure fluctuations that are qualitatively similar to the experimental data acquired during intermittency andThe stable operation of a turbulent combustor is not completely silent; instead, there is a background of small amplitude aperiodic acoustic fluctuations known as combustion noise. Pressure fluctuations during this state of combustion noise are multifractal due to the presence of multiple temporal scales that contribute to its dynamics. However, existing models are unable to capture the multifractality in the pressure fluctuations. We conjecture an underlying fractional dynamics for the thermoacoustic system and obtain a fractional-order model for pressure fluctuations. The data from this model has remarkable visual similarity to the experimental data and also has a wide multifractal spectrum during the state of combustion noise. Quantitative similarity with the experimental data in terms of the Hurst exponent and the multifractal spectrum is observed during the state of combustion noise. This model is also able to produce pressure fluctuations that are qualitatively similar to the experimental data acquired during intermittency and thermoacoustic instability. Furthermore, we argue that the fractional dynamics vanish as we approach the state of thermoacoustic instability.…
| Author details: | Alan J. Varghese, Aleksei ChechkinORCiDGND, Ralf MetzlerORCiDGND, Raman I. SujithORCiD |
|---|---|
| DOI: | https://doi.org/10.1063/5.0032585 |
| ISSN: | 1054-1500 |
| ISSN: | 1089-7682 |
| Pubmed ID: | https://pubmed.ncbi.nlm.nih.gov/33810715 |
| Title of parent work (English): | Chaos : an interdisciplinary journal of nonlinear science |
| Publisher: | American Institute of Physics, AIP |
| Place of publishing: | Melville |
| Publication type: | Article |
| Language: | English |
| Date of first publication: | 2021/03/02 |
| Publication year: | 2021 |
| Release date: | 2024/01/24 |
| Volume: | 31 |
| Issue: | 3 |
| Article number: | 033108 |
| Number of pages: | 9 |
| Funding institution: | DAADDeutscher Akademischer Austausch Dienst (DAAD)European Commission; J. C. Bose fellowship from the Department of Science and Technology (DST), Government of India [JCB/2018/000034/SSC] |
| Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
| DDC classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
| Peer review: | Referiert |
