Modelling of combustion acoustics sources and their dynamics in the PRECCINSTA burner test case

Abstract

A stochastic, hybrid computational fluid dynamics/computational combustion acoustics approach for combustion noise prediction is applied to the PRECCINSTA laboratory scale combustor (prediction and control of combustion instabilities in industrial gas turbines). The numerical method is validated for its ability to accurately reproduce broadband combustion noise levels from measurements. The approach is based on averaged flow field and turbulence statistics from computational fluid dynamics simulations. The three-dimensional fast random particle method for combustion noise prediction is employed for the modelling of time-resolved dynamics of sound sources and sound propagation via linearised Euler equations. A comprehensive analysis of simulated sound source dynamics is carried out in order to contribute to the understanding of combustion noise formation mechanisms. Therefrom gained knowledge can further on be incorporated for the investigation of onset of thermoacoustic phenomena. The method-inherent stochastic Langevin ansatz for the realisation of turbulence related source decay is analysed in terms of reproduction ability of local one-and two-point statistical input and therefore its applicability to complex test cases. Furthermore, input turbulence statistics are varied, in order to investigate the impact of turbulence on the resulting sound pressure spectra for a swirl stabilised, technically premixed combustor.

Early Detection of Coal Spontaneous Combustion by Complex Acoustic Waves in a Concealed Fire Source

“…In terms of the propagation characteristics of the sound waves to be measured that are emitted inside the area to be measured, the combustion sound is generated by the low frequency vibrations in the surrounding air medium excited upon molecular collisions from inside the heated object . Combustion sound has the characteristics of sound waves, follows the propagation of sound waves, and has a large penetration depth and propagation distance. , Acoustic receivers can be used to distinguish combustion sound from other infrasonic waves in the environment and identify the combustion sound produced by loose coal spontaneous combustion. Combining the principles of acoustics with the mechanism of spontaneous combustion, a robust theory can be elaborated to support the development of coal acoustic thermometry technologies.…”

“… 80 Combustion sound has the characteristics of sound waves, follows the propagation of sound waves, and has a large penetration depth and propagation distance. 81 , 82 Acoustic receivers can be used to distinguish combustion sound from other infrasonic waves in the environment and identify the combustion sound produced by loose coal spontaneous combustion. Combining the principles of acoustics with the mechanism of spontaneous combustion, a robust theory can be elaborated to support the development of coal acoustic thermometry technologies.…”

Computational study on the non-reacting flow in Lean Direct Injection gas turbine combustors through Eulerian-Lagrangian Large-Eddy Simulations

“…Nevertheless, as a consequence of experimental diagnosis shortcomings (e.g., the sampling frequency of the Stereo PIV system can be sometimes much smaller than the PVC frequency [157]), temporal and spatial-detailed CFD simulations have emerged as a potential tool to successfully characterise the coherent structures within the combustor through pressure, vorticity and species signals decomposition rather than dealing just with velocity. In this way, the POD technique applied to numerical studies has characterised the VBB and the transition to helical breakdown modes in non-reacting conditions [80,167,168], the combustion dynamics and flame interactions in reacting conditions [115,[169][170][171][172] and the impact of variations of thermal load and global equivalence ratio on combustion acoustics noise levels [173,174].…”