The dissipation and shear dispersion of entropy waves in combustor thermoacoustics

Morgans, Aimee S.; Goh, Chee Su; Dahan, Jeremy A.

doi:10.1017/jfm.2013.448

Cited by 92 publications

(151 citation statements)

References 20 publications

Supporting

Mentioning

132

Contrasting

Order By: Relevance

“…entropy wave) would be totally dispersed in the combustor [27]. This conclusion was rebutted by Morgans et al [28] through conduction of a direct numerical simulation of the advection of entropy waves by an adiabatic, incompressible channel flow. Morgans et al [28] modeled entropy waves as passive scalars and argued that they remain mostly conserved.…”

Section: Introductionmentioning

confidence: 89%

“…This conclusion was rebutted by Morgans et al [28] through conduction of a direct numerical simulation of the advection of entropy waves by an adiabatic, incompressible channel flow. Morgans et al [28] modeled entropy waves as passive scalars and argued that they remain mostly conserved. They further showed that the dispersion of these waves in their investigated configuration is negligibly small [28].…”

Section: Introductionmentioning

confidence: 92%

“…p′ being negligible), it may be concluded that s′ c p ≅ T′ T ̅ and also ρ′ ρ ≅ T′ T , [11,28] which indicate that the temperature (density) and entropy disturbances scale similarly. This similarity is the rationale behind generating the entropy wave by a transient temperature function at the channel 4 inlet.…”

Section: Problem Configuration and Boundary Conditionsmentioning

confidence: 98%

“…Morgans et al [28] modeled entropy waves as passive scalars and argued that they remain mostly conserved. They further showed that the dispersion of these waves in their investigated configuration is negligibly small [28].…”

Section: Introductionmentioning

confidence: 99%

“…The studies of Morgans et al [28] and Sattelmayer [27] considered turbulent flows and assumed adiabatic combustors with simple aerodynamics. Although disagreeing on the extent, they both demonstrated that hydrodynamic non-uniformities can destroy the entropy wave.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

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

2017

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 92%

Section: Problem Configuration and Boundary Conditionsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

2017

View full text Add to dashboard Cite

show abstract

Theoretical Formulation for the Investigation of Acoustic and Entropy-Driven Combustion Instabilities in Gas Turbine Engines

Singaravelu

Mariappan

Saha

2017

Combustion for Power Generation and Transportation

View full text Add to dashboard Cite

Dispersion of Entropy Perturbations Transporting through an Industrial Gas Turbine Combustor

Xia

Durán

Morgans

et al. 2017

Flow Turbulence Combust

Self Cite

View full text Add to dashboard Cite

In the context of combustion noise and combustion instabilities, the transport of entropy perturbations through highly simplified turbulent flows has received much recent attention. This work performs the first systematic study into the transport of entropy perturbations through a realistic gas turbine combustor flow-field, exhibiting large-scale hydrodynamic flow features in the form of swirl, separation, recirculation zones and vortex cores, these being ubiquitous in real combustor flows. The reacting flow-field is simulated using low Mach number large eddy simulations, with simulations validated by comparison to available experimental data. A generic artificial entropy source, impulsive in time and spatially localized at the flame-front location, is injected. The conservation equation describing entropy transport is simulated, superimposed on the underlying flow-field simulation. It is found that the transport of entropy perturbations is dominated by advection, with both thermal diffusion and viscous production being negligible. It is furthermore found that both the mean flow-field and the large-scale unsteady flow features contribute significantly to advective dispersion — neither can be neglected. The time-variation of entropy perturbation amplitude at combustor exit is well-modelled by a Gaussian profile, whose dispersion exceeds that corresponding to a fully-developed pipe mean flow profile roughly by a factor of three. Finally, despite the attenuation in entropy perturbation amplitude caused by advective dispersion, sufficient entropy perturbation strength is likely to remain at combustor exit for entropy noise to make a meaningful contribution at low frequencies.

show abstract

The dissipation and shear dispersion of entropy waves in combustor thermoacoustics

Cited by 92 publications

References 20 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

Theoretical Formulation for the Investigation of Acoustic and Entropy-Driven Combustion Instabilities in Gas Turbine Engines

Dispersion of Entropy Perturbations Transporting through an Industrial Gas Turbine Combustor

Contact Info

Product

Resources

About