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Showing 1 to 16 of 16 for “"Turbulent premixed flames"”.
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Propagation and topology in turbulent premixed flames
… this work, the phenomenon of self-interaction in turbulent premixed flames is investigated. This refers to the self-intersection of a highly curved flame iso-surface, which leads to local annihilation at the point of intersection as the enveloped mixture is depleted. With a rise in turbulence …
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Computations of Turbulent Premixed Flames Using Conditional Moment Closure
Lean premixed combustion is at present one of the most promising methods to reduce emissions and to maintain high efficiency in combustion systems. As the emission legislation becomes more stringent, modelling of turbulent premixed combustion has become an important tool for designing efficient and …
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Scalar dissipation rate based flamelet modelling of turbulent premixed flames
Lean premixed combustion has potential for reducing emissions from combustion devices without compromising fuel efficiency, but it is prone to instabilities which presents design difficulties. From emissions point of view reliable predictions of species formation rates in the flame zone are …
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Numerical investigation of effects of pressure and chemistry on characteristics of turbulent premixed flames
Turbulent premixed flames are used in many energy conversion and propulsion devices. The efficiency and performance of these devices are affected by operating conditions, which also affect the highly nonlinear turbulence-chemistry interactions (TCIs). Previous fundamental studies characterize TCIs …
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Characteristics of flame-turbulence interactions in freely propagating turbulent premixed flames under decaying and forced isotropic turbulence conditions
Turbulent premixed flames observed in energy conversion and propulsion applications are characterized by highly nonlinear, unsteady, and multi-scale processes. Previous numerical studies of freely propagating flames have utilized either forced or decaying background isotropic turbulence to provide …
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The use of chemiluminescence for the detection of temperature and fuel-to-air ratio in turbulent premixed flames
… and equivalence ratio has been developed for turbulent premixed flames. This method utilizes chemiluminescent signals to make correlations with flame temperature and equivalence ratio. Emissions from two radical groups are used for the correlations: an OH system at 309 nm and a CH system at …
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Turbulent flame propagation characteristics of high hydrogen content fuels
… in the use of combustors operating under lean, premixed conditions. Operating lean (excess air) lowers the level of nitrous oxides (NOx) emitted to the environment. In addition, concerns over climate change due to increased carbon dioxide (CO2) emissions and the need for energy independence in …
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Studies of premixed turbulent flames under flamelet assumptions
Turbulent burning velocity is a crucial factor in describing how fast premixed flame can burn, while it is still not well-predictable under various turbulence levels and flame conditions. A clearer definition of turbulent burning velocity based on the reaction rate will help understand the …
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Conditional source-term estimation methods for turbulent reacting flows
… methods are used to obtain chemical closure in turbulent combustion simulation. A Laminar Flamelet Decomposition (LFD) and then a Trajectory Generated Low-Dimensional Manifold (TGLDM) method are combined with CSE in Reynolds-Averaged Navier Stokes (RANS) simulation of non-premixed autoigniting …
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Simulating Bluff-body Flameholders: On the Use of Proper Orthogonal Decomposition for Combustion Dynamics Validation
… eddy simulations of the bluff body stabilized premixed combustion experiment. Large-eddy simulations (LES) using both Fluent and OpenFOAM were conducted to reproduce experiments conducted in an experimental test rig which was built as part of this work to study the behavior of turbulent …
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Large eddy simulation of premixed combustion using flamelets
… has potential to address unsteady phenomena in turbulent premixed flames and to capture turbulence scales and their influence on combustion. Thus, this approach is gaining interest in industry to analyse turbulent reacting flows. In LES, the dynamics of large-scale turbulent eddies down to a …
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Laser Diagnostics Applied to Lean Premixed Swirling Flames - Simultaneous Flow Field and Scalar Measurements
… here includes experimental studies of lean premixed swirling flames. Various laser-based optical diagnostic techniques were used to collect information under different operational conditions. Combined flow- and scalar field measurements were performed at high repetition rates for detailed …
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Isosurface Interactions Within Turbulent Premixed Hydrogen and Hydrocarbon Flames
… better insight into isosurface interactions in premixed turbulent flames. These interactions for a suitable isosuface corresponding to the reaction zone can be interpreted as flame-flame interactions. Isosurface interactions can be identified with the help of Morse theory of critical points and …
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Development of Laser-Spectroscopic Techniques for New Detection Schemes in Combustion Diagnostics
… of minor species such as OH and C2H2 produced in flames, as well as of stable species such as CO2, CH4 and H2O was demonstrated. The signal-to-noise ratio obtained was higher than for IRLIF. Finally, the development of planar LIF (PLIF) for CH involving improved detection sensitivity for a …
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Physical Insights of Non-Premixed MILD Combustion using DNS
… Simulation (DNS) is used to study turbulence, premixed flames and MILD combustion to obtain these additional physical insights. In a first stage, the scale-locality of the energy cascade is analysed by applying a multiscale analysis methodology, called the bandpass filter method, on DNS of …
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Influences of the Darrieus-Landau instability on premixed turbulent flames
… its inventors. The instability, which prevents flames from being too flat, was thought to lead immediately to turbulent flames. Recent studies, initiated by weakly nonlinear analyses and extended by two-dimensional simulations suggest that this is not the case. It was established that the flame, …