We experimentally investigate the dynamic behavior of combustion instability in a lean premixed gas-turbine combustor from viewpoint nonlinear dynamics. A time series analysis combination with surrogate data method clearly reveals that as equivalence ratio increases, undergoes significant transition stochastic fluctuation to periodic oscillation through low-dimensional chaotic oscillation. also show forecasting is useful for predicting short-term combustor, which has not been addressed...

We propose an online method of detecting combustion instability based on the concept dynamical system theory, including characterization dynamic behavior instability. As important case study relevant to encountered in fundamental and practical systems, we deal with dynamics close lean blowout (LBO) a premixed gas-turbine model combustor. The relatively regular pressure fluctuations generated by thermoacoustic oscillations transit low-dimensional intermittent chaos owing appearance burst...

We characterize complexities in combustion instability a lean premixed gas-turbine model combustor by nonlinear time series analysis to evaluate permutation entropy, fractal dimensions, and short-term predictability. The dynamic behavior near blowout exhibits self-affine structure is ascribed fractional Brownian motion. It undergoes chaos the onset of oscillations with slow amplitude modulation. Our results indicate that capable characterizing close blowout.

We present a detailed study on the characterization of degeneration process in combustion instability based dynamical systems theory. deal with lean premixed-type gas-turbine model combustor, one fundamentally and practically important systems. The dynamic behavior close proximity to blowout is dominated by stochastic transits periodic oscillations created thermoacoustic via chaos increasing equivalence ratio [Chaos 21, 013124 (2011); Chaos 22, 043128 (2012)]. Thermoacoustic degenerate...

We experimentally study the dynamic behavior of intermittent combustion oscillations by time series analysis in terms nonlinear forecasting, symbolic dynamics, and statistical complexity, including detection change dynamical state based on dynamics graph networks. observe sudden switching back forth between irregular small-amplitude regular large-amplitude pressure fluctuations. The local prediction method, permutation spectrum test, Rényi complexity–entropy curve clearly identify possible...

We conduct an experimental study using time series analysis based on symbolic dynamics to detect a precursor of frequency-mode-shift during thermoacoustic combustion oscillations in staged aircraft engine model combustor. With increasing amount the main fuel, significant shift dominant frequency-mode occurs noisy periodic dynamics, leading notable increase oscillation amplitudes. The sustainment is clearly shown by multiscale complexity-entropy causality plane terms statistical complexity. A...

An open lean-premixed hydrogen/air low-swirl (LPHALS) turbulent flame exhibiting a pronounced peak in its combustion noise spectra, is investigated numerically using hybrid Computational Fluid Dynamics/Computational Aero-Acoustics (CFD/CAA) framework. Under this framework, the reacting flow-field of computed via Large-Eddy Simulation (LES), while direct it produces captured by solving Acoustic Perturbation Equations for Reacting Flows (APE-RF). Flame configuration and simulation conditions...

Large-eddy simulation is performed to simulate high-frequency combustion instability in a single-element atmospheric combustor. Simulations are conducted for corresponding combustion-instability experiments, and the self-excited successfully captured. The first tangential mode of chamber excited large-eddy simulation, amplitude frequency pressure fluctuations consistent with experimental observations. was observed at 1 kHz, peak-to-peak approximately 4% time-averaged pressure. higher-order...

Large-eddy simulation (LES) of a lean-premixed hydrogen turbulent jet flame with combustion instability (CI) in low-swirl combustor (LSC) is performed by employing dynamically thickened model detailed chemical reaction 9 species and 20 reactions, the LES validity CI characteristics are investigated detail. The results show that present can accurately reproduce experimentally observed such as intensity, frequency, sporadic decay pressure oscillations, flame–flow interaction inducing periodic...

A staged injector developed by JAXA and fueled with kerosene is studied in a high-pressure combustion experiment. With stable pilot fuel flow rate, the rate main stage progressively increased. high-speed OH-planar laser-induced fluorescence (PLIF) system used to record flame motion at 10,000 fps. In beginning of recording, behavior dominated relatively low-frequency rotation due swirling flow. These rotational motions then coexist thermo-acoustic instability around 475 Hz which increases...

A hybrid computational fluid dynamics (CFD)/computational aero-acoustics (CAA) approach, in which large-eddy simulation (LES) and APE-RF (solution of the acoustic perturbation equations for reacting flows) are employed CFD CAA, respectively, calling it LES/APE-RF is used to analyze influence a wall on combustion noise from lean-premixed gaseous hydrogen/air low-swirl turbulent jet flame. The boundary conditions pertaining system formulated account reflection wall. results show that sound...