Prediction and control of combustion instabilities in real engines

Poinsot, Thiérry

doi:10.1016/j.proci.2016.05.007

Cited by 561 publications

(229 citation statements)

References 155 publications

(192 reference statements)

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“…Nevertheless, due to the flow complexity in such configurations making any precise conclusion about the evolution of entropy waves is still very difficult [30]. Further, most recent studies have shown that entropy waves do not necessarily propagate as passive scalars and can affect the base flow [31].…”

Section: Introductionmentioning

confidence: 99%

On the dissipation and dispersion of entropy waves in heat transferring channel flows

2017

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This paper investigates the hydrodynamic and heat transfer effects upon the dissipation and dispersion of entropy waves in non-reactive flows. These waves, as advected density inhomogeneities downstream of unsteady flames, may decay partially or totally before reaching the exit nozzle, where they are converted into sound. Attenuation of entropy waves dominates the significance of the subsequent acoustic noise generation.Yet, the extent of this decay process is currently a matter of contention and the pertinent mechanisms are still largely unexplored. To resolve this issue, a numerical study is carried out by compressible large eddy simulation (LES) of the wave advection in a channel subject to convective and adiabatic thermal boundary conditions. The dispersion, dissipation and spatial correlation of the wave are evaluated by post-processing of the numerical results. This includes application of the classical coherence function as well as development of nonlinear quantitative measures of wave dissipation and dispersion. The analyses reveal that the high frequency components of the entropy wave are always strongly damped. The survival of the low frequency components heavily depends upon the turbulence intensity and thermal boundary conditions of the channel. In general, high turbulence intensities and particularly heat transfer intensify the decay and destruction of the spatial coherence of entropy waves. In some cases, they can even result in the complete annihilation of the wave. The current work can therefore resolve the controversies arising over the previous studies of entropy waves with different thermal boundary conditions.

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Section: Introductionmentioning

confidence: 99%

On the dissipation and dispersion of entropy waves in heat transferring channel flows

2017

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“…Rate of increase of pressure is defined by the speed of explosive combustion. Many experimental works [7][8][9][10][11] and works in which this process numerically is modelled [12][13][14][15][16] are devoted to studying of this question. At explosion in closed volume terminal pressure of explosion is defined by a share of the burned-down substance.…”

Section: Methodsmentioning

confidence: 99%

Ensuring explosion safety of residential buildings

Gorev

2018

MATEC Web Conf.

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Abstract. Explosions of air -and-gas mixtures in residential buildingsincident dangerous and recently extended. Unlike the production explosive buildings residential buildings are not protected by express requirements. In this work the possibility of protection of these buildings by means of a depressurization through the coming-off apertures is analyzed. These apertures can be closed by windows or express light-weight constructions. In work it is shown that fastenings of these designs in an aperture considerably are reduced by effectiveness of opening of apertures as the incipient state of driving of protective designs does not open space for venting of gases. Explosion pressure at the same time grows as in closed volume and until opening can reach critical value and cause destruction of the protecting and load-bearing frames. By the time of opening of an aperture for venting of gases the Safety design already has sufficient speed, and discovery of the area in that case happens quickly and pressure increases slightly. The main pressure boost happens before destruction of fastening of mild designs and at their driving in an aperture when volume can be considered pressure-tight. Calculations show: that designs with the specific surface density р30 kg/m2 and depth of seal of 0,2 m do not provide protection of residential buildings. The modern windows to double-glazed windows and their fastening are close to these conditions.

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“…Under such conditions, the combustor suffers high-amplitude thermoacoustic limit cycles leading to high-cycle fatigue of the components and potentially to sudden mechanical failure, which must be avoided at all cost. Nowadays, it is still very difficult to predict the occurrence of thermoacoustic instabilities in real engines where the combustion system complexity is markedly increased compared to laboratory layouts [3]. The latter academic configurations nevertheless provide extremely valuable information on the fundamental features of thermoacoustic problems in practical combustors.…”

Section: Introductionmentioning

confidence: 99%

Effect of wall thermal inertia upon transient thermoacoustic dynamics of a swirl-stabilized flame

Bonciolini¹,

Ebi²,

Doll³

et al. 2019

Proceedings of the Combustion Institute

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This paper shows the importance of considering the thermal state of a combustor to investigate or predict its thermoacoustic stability. This aspect is often neglected or regarded as less important than the effect of the operating parameters, such as thermal power or equivalence ratio, but under certain circumstances it can have a dramatic influence on the development of the instabilities. The paper presents experimental results collected from a combustor featuring a lean swirl-stabilized flame exhibiting thermoacoustic instability at some operating conditions. It is shown that this instability is caused by a change of the flame topology that is induced by the progressive increase of the wall temperature with the thermal power. This dependence of the instability on wall temperature leads to inertial effects and hysteresis when the operating condition is changed dynamically. A low-order model of the system reproducing this remarkable dynamics is proposed and validated against the experimental data.

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Prediction and control of combustion instabilities in real engines

Cited by 561 publications

References 155 publications

On the dissipation and dispersion of entropy waves in heat transferring channel flows

On the dissipation and dispersion of entropy waves in heat transferring channel flows

Ensuring explosion safety of residential buildings

Effect of wall thermal inertia upon transient thermoacoustic dynamics of a swirl-stabilized flame

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