Systematic Analysis of Lean-Premixed Swirl-Stabilized Combustion

Abstract

A systematic data-analysis procedure is established to explore the underlying mechanisms responsible for driving unsteady flow motions in gas-turbine combustors. Various data processing and analysis approaches are developed and implemented. These include triple decomposition of flowfield, vortex identification, spectral analysis, linear acoustic modal and hydrodynamic stability analyses, and proper orthogonal decomposition. The work allows for a detailed investigation of the mechanisms of energy exchange between the mean, periodic, and turbulent flowfields in a combustion chamber, as well as their collective interactions with chemical heat release. As a specific example, the combustion dynamics in a lean-premixed swirl-stabilized combustor operating under a variety of conditions is carefully examined, based on an avalanche of time-resolved numerical data obtained from large-eddy simulations.

Large-eddy simulation and acoustic analysis of a turbulent flow field in a swirl-stabilized combustor

“…In this study, the acoustic potential energy-based POD method was used to effectively capture acoustic motion in the compressible flow field [8,14]. The flow variable vector is defined as pressure fluctuation ' ( ') q p = , and the inner product is as follows:…”

“…It is useful for indentifying fluctuation modes because it can decompose the flow structure into an independent base [5,6,8].…”

“…Grinstein et al also investigated round and rectangular swirl-stabilized gas turbine combustor flows, and they found that the combustor geometry strongly affects the vertical flow, and hence also the flame and its dynamics [3,4]. Sung and Huang et al investigated unsteady flame dynamics in a lean-premixed swirlstabilized combustor [5][6][7][8]. Their results indicated that the inlet temperature and equivalent ratio are the two most important factors affecting the stability characteristics of the combustor.…”

Identification and analysis of instability in non-premixed swirling flames using LES

“…The identification of the oscillation modes and the effect of a PVC on instability remains a challenge especially over a wide range of practical engineering applications. For example, the interactions between different instability oscillations can cause considerable acoustic fluctuations as a result of the pressure field [5][6][7].…”

Combustion Instability Problems Analysis for High-Pressure Jet Engine Cores

“…This methodology combines experiments and numerical methods where Large Eddy Simulation (LES) and acoustic analysis are the main components: LES has become a standard tool in the study of the dynamics of turbulent flames for gas turbines 4,[11][12][13][14][17][18][19]22,[24][25][26][27][28][29] or for piston engines 16 while acoustic analysis is a standard numerical method for predicting acoustic modes in cavities which has been extended to reacting flow cases by multiple authors in the past 5,6,8,24 . These tools will be described briefly here since the paper concentrates on the results they provide rather than on their theoretical basis.…”