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Showing 1 to 20 of 26 for “"Combustion dynamics"”.
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Combustion dynamics of individual reactive material particles
… Metals are attractive because of their high combustion enthalpies and temperatures. Quantitative descriptions of the combustion processes and mechanisms for both pure metal and composite particles are also desired for their proper implementation in specific applications. Among reactive …
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Combustion dynamics of metal powders in mixed gas flows
Predictive mechanisms for particle ignition and combustion rates are required in order to develop optimized propellant and energetic formulations using micron-sized metal powders, such as aluminum and magnesium. Most current descriptions are based on laboratory experiments performed in stationary …
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Suppression of premixed combustion dynamics utilizing microjet air injection
… of thermoacoustic instability in continuous combustion systems is a major challenge in the field of propulsion and power generation. With the current environmental and political pressure that is being placed on the consumption of fossil fuels, this subject has become even more critical. In …
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Effects of Thermoacoustic Oscillations on Spray Combustion Dynamics with Implications for Lean Direct Injection Systems
… Intuitively, development of effective active combustion control methodologies is strongly dependent on the knowledge of the onset and sustenance of thermoacoustic instabilities. Specially, non-premixed spray combustion environment pose additional challenges due to the inherent unstable …
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Simulating Bluff-body Flameholders: On the Use of Proper Orthogonal Decomposition for Combustion Dynamics Validation
… 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 premixed flames …
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An Experimental Investigation of Self-Excited Combustion Dynamics in a Single Element Lean Direct Injection (LDI) Combustor
<p>The management of combustion dynamics in gas turbine combustors has become more challenging as strict NOx/CO emission standards have led to engine operation in a narrow, lean regime. While premixed or partially premixed combustor configurations such as the Lean Premixed Pre-vaporized (LPP), Rich …
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Swirl-stabilized lean-premixed flame combustion dynamics: An experimental investigation of flame stabilization, flame dynamics and combustion instability control strategies
Though modern low-emission combustion strategies have been successful in abating the emission of pollutants in aircraft engines and power generation gas turbines, combustion instability remains one of the foremost technical challenges in the development of next generation lean premixed combustor …
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Effects of trans / supercritical behavior of carbon dioxide on power and propulsion applications
… design. However, this can have an impact on the combustion dynamics, and the impact of trans-critical conditions is unknown. A reduced order model framework was developed to assess the impact of droplet evaporation time on the combustion dynamics under sub-, trans- and supercritical conditions. …
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Metal based reactive nanocomposites prepared by cryomilling
… for aluminum as fuel additives to achieve higher combustion temperatures and stronger pressure pulses for applications in advanced munitions systems. Two applications are addressed in this work. In the applications for explosives designed to defeat stockpiles of chemical and biological weapons, it …
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Combustion Physics and Inverse Modeling of Energetic Materials
Energetic material combustion involves intricate multi-scale and multi-phase dynamics, where the interplay of chemical reaction and transport processes results in complex wave patterns across a wide range of length scales from nano to millimeter. Our limited fundamental understanding of these …
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Hybrid Eulerian/Lagrangian 3D methods for high Reynolds number reactive flows
Research in advanced combustion modeling is critical to developing control strategies for optimized propulsion systems, especially with regard to stability, emissions, and power density. Examining combustion dynamics and control using numerical simulations, however, presents several challenges, …
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Nanosecond Pulsed Plasmas in Dynamic Combustion Environments
Plasma assisted combustion (PAC) is a promising technology for extending combustion operating envelopes with a low energy cost relative to flame power. It has been investigated for use in various situations, particularly those where combustion is being performed near flammability limits imposed by …
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Towards predicting dynamics in turbulent premixed combustion using PIV-PLIF measurements of flow-flame microstructure
Combustion dynamics are critical to the development of high-efficiency, low-emission and fuel-flexible combustion systems used for propulsion and power generation. Predicting the onset of dynamics remains a challenge because of the complex interactions among several multi-scale phenomena, including …
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Development of Reduced-Order Flame Models for Prediction of Combustion Instability
Lean-premixed combustion has the advantage of low emissions for modern gas turbines, but it is susceptible to thermoacoustic instabilities, which can result in large amplitude pressure oscillations in the combustion chamber. The thermoacoustic limit cycle is generated by the unsteady heat release …
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Fundamental studies in hydrogen-rich combustion : instability mechanisms and dynamic mode selection
… produced by coal gasification. Lean premixed combustion, the preferred high-efficiency, low-emissions operating mode in these combustors, is susceptible to strong instabilities even in ordinary fuels. Because hydrogen-rich fuels have combustion properties which depend strongly on composition, …
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Active combustion control : modeling, design and implementation
Continuous combustion systems common in propulsion and power generation applications are susceptible to thermoacoustic instability, which occurs under lean burn conditions close to the flammability where most emissions and efficiency benefits are achieved, and near stoichiometry where often high …
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Two contrasting approaches to auto-ignition modelling for HCCI engines
… models formulated for the emulation of combustion dynamics in Homogeneous Charge Compression Ignition (HCCI) engines. The first (empirical) auto-ignition model was adapted from its previously published form, for HCCI engine model implementation. This model was then combined with an …
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Development of mesoscale burner arrays for next generation compact gas turbines
… burner array was designed to improve the overall combustion stability by exploiting flame-to-flame interactions under fuel-lean operation. Moreover, its design can be adjusted by scaling the element dimensions or array size to flexibly accommodate a wide range of combustion power outputs. The …
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Combustion of fine magnesium particles
… alloys as reactive materials prompted studies of combustion mechanisms for particles of such alloys with different Al/Mg ratios. Reference experiments with pure Al and Mg powders are also desired to better understand and model combustion of the respective alloys. While combustion of pure Al …
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Dynamics, stability and scaling of turbulent methane oxy-combustion
… for reducing CO₂ emissions, with oxy-fuel combustion being one of the most promising technologies because of it is high efficiency and low cost. In oxy-combustion, CH₄/O₂/CO₂ mixtures burn at low temperatures (~~1700 K), high pressures (~~40 bar), where laminar burning velocities are about …
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