Kowshik, SA and Shridhar, S and Treleaven, NCW (2021) Towards reduced order models of small-scale acoustically significant components in gas turbine combustion chambers. In: ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition, 7-11 jun 2021.
Full text not available from this repository.Abstract
Gas turbine combustion chambers contain numerous small-scale features that help to dampen acoustic waves and alter the acoustic mode shapes. This damping helps to alleviate problems such as thermoacoustic instabilities. During computational fluid dynamics simulations (CFD) of combustion chambers, these small-scale features are often neglected as the corresponding increase in the mesh cell count augments significantly the cost of simulation while the small physical size of these cells can present problems for the stability of the solver. In problems where acoustics are prevalent and critical to the validity of the simulation, the neglected small-scale features and the associated reduction in overall acoustic damping can cause problems with spurious, non-physical noise and prevents accurate simulation of transients and limit cycle oscillations. Low-order dynamical systems (LODS) and artificial neural networks (ANNs) are proposed and tested in their ability to represent a simple two-dimensional acoustically forced simulation of an orifice at multiple frequencies. These models were built using compressible CFD, using OpenFOAM, of an orifice placed between two ducts. The acoustic impedance of the orifice has been computed using the multi-microphone method and compared to a commonly used analytical model. Following this, the flow field downstream of the orifice has been modelled using both a LODS and ANN model. Both methods have shown the ability to closely represent the simulated dynamical flows at much lower computational cost than the original CFD simulation. This work opens the possibility of models that can dynamically predict the flow through, for instance, acoustic liners, dilution ports and fuel injectors in real engines during thermoacoustic instabilities without having to mesh and simulate these small-scale features directly. Such models may also assist in the accurate simulation of flame quenching due to cooling flows or the design of effusion cooled aerodynamic surfaces such as nozzle guide vanes (NGVs) and turbine blades. Copyright © 2021 by ASME.
| Item Type: | Conference Paper |
|---|---|
| Publication: | Proceedings of the ASME Turbo Expo |
| Publisher: | American Society of Mechanical Engineers (ASME) |
| Additional Information: | The copyright for this article belongs to American Society of Mechanical Engineers (ASME) |
| Keywords: | Acoustic impedance; Aerodynamics; Combustion chambers; Computational fluid dynamics; Damping; Dynamical systems; Gas turbines; Heat conduction; Mesh generation; Nozzle design; Orifices; Thermoacoustics; Turbine components; Turbomachine blades, Acoustics waves; Computational fluid dynamics simulations; Gas-turbine combustion; Low order; Mode shapes; Reduced order modelling; Reduced-order model; Small scale; Small-scale features; Thermoacoustic instability, Neural networks |
| Department/Centre: | Division of Mechanical Sciences > Mechanical Engineering |
| Date Deposited: | 28 Nov 2021 10:12 |
| Last Modified: | 28 Nov 2021 10:12 |
| URI: | http://eprints.iisc.ac.in/id/eprint/70317 |
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