Development of Combustion Response Functions in a Subscale High Pressure Longitudinal Combustor

Abstract

An automated data isolation and reduction method has been developed to generate meaningful graphical combustion response functions from a combination of pressure amplitude and various image analysis metrics. It was developed and tested using pressure measurements and high speed imaging of combustion light taken from an unstable high pressure subscale single element longitudinal combustor. The code was used to isolate time slices of near stationary pressure amplitude, and process the corresponding images into combustion response approximated by Global I', Center of Intensity, POD, and DMD. Overall the generated combustion response functions generally agreed with expected behavior of an element located at the pressure antinodes of multiple modes of a longitudinal combustor. The response functions generally showed positively correlated linear behavior with pressure amplitude. Results from POD and DMD both successfully isolated the prominent spatial and temporal light emission behavior.

High-Speed Flame Radiation Imaging of Thermoacoustic Coupling in a High Pressure Research Thrust Chamber

“…DMD as described by Schmid et al [27] enables the extraction of dominant periodically fluctuating phenomena at different frequencies. In the past, the DMD method has been used in thermoacoustic instability research in order to extract the distributed flame response at certain frequencies from flame visualization data [15,19,28,29].…”

Low-order model studies of combustion instabilities in a DVRC combustor

“…Different approaches have been explored for developing response functions. Wierman et al 1 used proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) for reducing experimental data, more specifically high speed imaging of combustion light taken from an unstable high pressure subscale single element longitudinal combustor. Chong et al, 2 focusing on gas turbine, extract response functions from LES data with a system identification process that uses Wiener-Hopf equation (an optimal linear least square estimator) to identify flame transfer function.…”

Numerical issues in modeling combustion instability by quasi-1D Euler equations

“…Even if full-scale experimental campaigns have been performed, 1 with great improvement in the phenomenon knowledge, the required economical effort would be prohibitive today, with consequent necessity for alternative investigative procedures. As far as experiments are concerned, great interest is addressed to subscale test combustors, [2][3][4][5] requiring a more limited effort in terms of practical realization and allowing to achieve appreciable results in a relatively short time. Experiments are usually supported by simulations that can provide useful insight in the mechanisms sustaining instability and estimation of the quantities of interest.…”