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Journal ArticleDOI

Vortex-driven acoustically coupled combustion instabilities

01 Apr 1987-Journal of Fluid Mechanics (Cambridge University Press)-Vol. 177, Iss: -1, pp 265-292
TL;DR: In this article, the authors investigated low-frequency vortex-driven combustion instability in the case of a multiple inlet combustor with dump and showed that lowfrequency instabilities are acoustically coupled and occur at the eigenfrequencies of the system.
Abstract: Combustion instability is investigated in the case of a multiple inlet combustor with dump. It is shown that low-frequency instabilities are acoustically coupled and occur at the eigenfrequencies of the system. Using spark-schlieren and a special phase-average imaging of the C 2 -radical emission, the fluid-mechanical processes involved in a vortex-driven mode of instability are investigated. The phase-average images provide maps of the local non-steady heat release. From the data collected on the combustor the processes of vortex shedding, growth, interactions and burning are described. The phases between the pressure, velocity and heat-release fluctuations are determined. The implications of the global Rayleigh criterion are verified and a mechanism for low-frequency vortex-driven instabilities is proposed.
Citations
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Journal ArticleDOI
TL;DR: In this article, a boundary condition formulation for the Navier-Stokes equations is proposed, which is compatible with non-disjoint algorithms applicable to direct simulations of turbulent flows.

3,214 citations

Journal ArticleDOI
TL;DR: A comprehensive review of the advances made over the past two decades in this area is provided in this article, where various swirl injector configurations and related flow characteristics, including vortex breakdown, precessing vortex core, large-scale coherent structures, and liquid fuel atomization and spray formation are discussed.

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Journal ArticleDOI
TL;DR: In this paper, the authors present a discussion of different methods which can be used to suppress combustion instabilities using active control, as well as a review of the work which has recently been performed in this area of combustion research.

789 citations

Journal ArticleDOI
01 Jan 2002
TL;DR: A broad survey of combustion research can be found in this article, where a number of closed loop feedback concepts are used to improve the combustion process as demonstrated by applications to automotive engines.
Abstract: Combustion dynamics constitutes one of the most challenging areas in combustion research. Many facets of this subject have been investigated over the past few decades for their fundamental and practical implications. Substantial progress has been accomplished in understanding analysis, modeling, and simulation. Detailed laboratory experiments and numerical computations have provided a wealth of information on elementary dynamical processes such as the response of flames to variable strain, vortex rollup, coupling between flames and acoustic modulations, and perturbed flame collisions with boundaries. Much recent work has concerned the mechanisms driving instabilities in premixed combustion and the coupling between pressure waves and combustion with application to the problem of instability in modern low NO x heavyduty gas turbine combustors. Progress in numerical modeling has allowed simulations of dynamical flames interacting with pressure waves. On this basis, it has been possible to devise predictive methods for instabilities. Important efforts have also been directed at the development of the related subject of combustion control. Research has focused on methods, sensors, actuators, control algorithms, and systems integration. In recent years, scaling from laboratory experiments to practical devices has been achieved with some successebut limitations have also been revealed. Active control of combustion has also evolved in various directions. A number of experiments on laboratory-scale combustors have shown that the amplitude of combustion instabilities could be reduced by applying control principles. Full-scale terrestrial application to gas turbine systems have allowed an increase of the stability margin of these machines. Feedback principles are also being explored to control the point of operation of combustors and engines. Operating point control has special importance in the gas turbine field since it can be used to avoid operation in unstable regions near the lean blowoff limits. More generally, closed loop feedback concepts are useful if one wishes to improve the combustion process as demonstrated by applications to automotive engines. Many future developments of combustion will use such concepts for tuning, optimization, and emissions reduction. This article proposes a broad survey of these fast-moving areas of research.

726 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the utility of several experimental observables as measurements of local burning and heat release rates for a premixed stoichiometric N2-diluted methane-air flame in two-dimensional unsteady vortical flow.

537 citations

References
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D. T. Harrje1
01 Jan 1972
TL;DR: In this paper, the extent of combustion instability problems in liquid propellant rocket engines and recommendations for their solution are discussed, both theoretical and experimental, with emphasis on fundamental principles and relationships between alternative approaches.
Abstract: The solution of problems of combustion instability for more effective communication between the various workers in this field is considered. The extent of combustion instability problems in liquid propellant rocket engines and recommendations for their solution are discussed. The most significant developments, both theoretical and experimental, are presented, with emphasis on fundamental principles and relationships between alternative approaches.

418 citations

Book
01 Jan 1971

320 citations

Journal ArticleDOI
TL;DR: In this article, a study of the noise produced by turbulent premixed flames stabilized on open burners is described, and it is shown that such flames may be represented acoustically as a collection of monopole sound sources in the combustion zone.
Abstract: A study of the noise produced by turbulent premixed flames stabilized on open burners is described. It is shown that such flames may be represented acoustically as a collection of monopole sound sources in the combustion zone. The radiated sound pressure is dependent on the rate of change of the rate of increase of volume of the gas during combustion, which varies owing to the turbulence in the flow. The rate of volume increase is proportional to the rate of consumption of combustible gas mixture in the flame. To measure this quantity, an optical technique has been developed which relies on observations of changes in the intensity of emission from the free radicals C 2 or CH generated in the reaction zone. Good quantitative agreement is obtained between the radiated sound pressures calculated from these intensity measurements and the values recorded simultaneously with a microphone. A correlation observed between the mean emission intensities of C 2 and CH radicals and the total flow rate of combustible gas mixture both in the laminar and turbulent flames, and in their transition region, supports the wrinkled laminar flame concept of turbulent flame propagation.

261 citations

Journal ArticleDOI
TL;DR: In this article, the activation energy asymptotics method was used to describe the behavior and characteristics of adiabatic laminar flamelets involving counterflowing reactants and products as they arise in premixed turbulent flames.

171 citations