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.

Early detection of thermoacoustic instabilities is interest to both applied physicists and engineers, avoid resonance leading self-destruction gas-based engines turbines. This study shows how a combination complex-network physics machine learning can be used detect precursor instabilities, which help prevent the onset potentially destructive combustion-driven instability.

Thermoacoustic instability is of interest to applied physicists and engineers as a significant, widely observed phenomenon in various types engines. This study shows how use pragmatic, online detection methodology, based on the theory complex networks, control unstable combustion turbulent thermoacoustic system. combination network physics, nonlinear dynamics, engineering helps avoid blowout conditions engine shutdown.

We present an experimental study on the characterization of dynamic behavior flow velocity field during thermoacoustic combustion oscillations in a turbulent confined combustor from viewpoints statistical complexity and complex-network theory, involving detection precursor oscillations. The multiscale complexity-entropy causality plane clearly shows possible presence two dynamics, noisy periodic chaos, shear layer regions (1) between outer recirculation region dump plate wake centerbody (2)...

We have examined the dynamics of self-excited thermoacoustic instability in a fundamentally and practically important gas-turbine model combustion system on basis complex network approaches. incorporated sophisticated networks consisting cycle phase space networks, neither which has been considered areas physics science. Pseudo-periodicity high-dimensionality exist instability, including possible presence clear power-law distribution small-world-like nature.

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 numerically study the spatiotemporal dynamics and early detection of thermoacoustic combustion instability in a model rocket combustor using theories complex networks synchronization. The turbulence network, which consists nodes vertexes weighted between vortices, can characterize structure flow field during instability. transfer entropy allows us to identify driving region In addition order parameter, phase parameter newly proposed this is useful for capturing precursor

We conduct an experimental study on early detection of thermoacoustic combustion oscillations using a method combining statistical complexity and machine learning, including the characterization intermittent oscillations. Abrupt switching from aperiodic small-amplitude to periodic large-amplitude vice versa appears in pressure fluctuations. The dynamic behavior fluctuations represents chaos. complexity-entropy causality plane effectively captures subtle changes state during transition...

We experimentally conduct an early detection of thermoacoustic instability in a staged single-sector combustor using novel methodology that combines symbolic dynamics and machine learning. propose two invariants this study: the determinisms joint recurrence plots DJ ordinal transition pattern-based DT. These enable us to capture phase synchronization between acoustic pressure heat release rate fluctuations associated with precursor instability. The latent space consisting DT, which is...

We conduct an experimental study of the attenuation behavior thermoacoustic combustion instability from viewpoints complex networks and synchronization. The spatiotemporally phase-synchronized state between vertexes in weighted near injector rim is notably degenerated as suppressed by a steady air jet issued rim. synchronization index clearly captures mutual coupling pressure heat release rate fluctuations. decrease periodicity noisy-periodic oscillations flow velocity field significantly...

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 study the formation mechanism of high-frequency combustion oscillations in a model rocket combustor from viewpoints symbolic dynamics and complex networks. The flow velocity fluctuations fuel injector generated by pressure give rise to periodic ignition unburnt fuel/oxidizer mixture, resulting significant change heat release rate combustor. drive before transition state, while gradually begin significantly affect during oscillations. directional feedback process subsequent is identified...

We investigate the drag reduction effect of streamwise travelling wave-like wall deformation in a high-Reynolds-number turbulent channel flow by large-eddy simulation (LES). First, we assess validity subgrid-scale models uncontrolled and controlled flows. For friction Reynolds numbers $Re_\tau = 360$ $720$ , Smagorinsky wall-adapting local eddy-viscosity (WALE) with damping function can reproduce well mean velocity profile obtained direct numerical (DNS) both flows, leading to small...

The dynamic behavior of swirling premixed flames generated by the effect gravitational orientation has been experimentally and numerically investigated. When direction relative to flame front is changed, i.e., in inverted gravity $(\ensuremath{-}1G)$, an unstable formed a limited domain equivalence ratio swirl number. time history fluctuation shows that high-energy chaotic motion superimposed on periodic oscillation vortex combustion products. This results becoming deterministically chaotic....

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...

Forecasting of aperiodic time series is a compelling challenge for science. In this work, we analyze spectrophotometric data, proportional to the concentrations two forms thermoreversible photochromic spiro-oxazine, that are generated when cuvette containing solution spiro-oxazine undergoes photoreaction and convection due localized ultraviolet illumination. We construct phase space system using Takens' theorem calculate Lyapunov exponents correlation dimensions ascertain chaotic character...

We have intensively examined the dynamic behavior of flame front instability in a lean swirling premixed generated by change gravitational orientation [H. Gotoda, T. Miyano, and I. G. Shepherd, Phys. Rev. E 81, 026211 (2010)] from viewpoints complex networks, symbolic dynamics, statistical complexity. Here, we considered permutation entropy combination with surrogate data method, spectrum test, multiscale complexity-entropy causality plane incorporating scale-dependent approach, none which...

We apply nonlinear forecasting to the time series of flame front instability induced by radiative heat loss test for short-term predictability and long-term unpredictability characteristic deterministic chaos in instability. Our results indicate that represents high-dimensional generated via period-doubling cascade process reported our previous study [H. Gotoda, K. Michigami, Ikeda, T. Miyano, Combust Theory Modell. 14, 479 (2010)], while its behavior is predictable using a local predictor...

We conduct a numerical study on the dynamic behavior of buoyancy-induced turbulent fire from viewpoints symbolic dynamics, complex networks, and statistical complexity. Here, we consider two classes entropies: permutation entropy network in ε-recurrence both which evaluate degree randomness underlying dynamics. These entropies enable us to capture significant changes flow velocity fluctuations. The possible presence important low-dimensional deterministic chaos near field dominated by motion...

We are intensively studying the chaos via period-doubling bifurcation cascade in radiative heat-loss-induced flame front instability by analytical methods based on dynamical systems theory and complex networks. Significant changes dynamics chaotic region, which cannot be seen diagrams, were successfully extracted from recurrence quantification analysis nonlinear forecasting network entropy. The temporal of fuel concentration well-developed region is much more complicated than that...