Download or read book Experimental Investigation of Premixed Turbulent Hydrocarbon Air Bunsen Flames written by Parsa Tamadonfar and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Through the influence of turbulence, the front of a premixed turbulent flame is subjected to the motions of eddies that leads to an increase in the flame surface area, and the term flame wrinkling is commonly used to describe it. If it is assumed that the flame front would continue to burn locally unaffected by the stretch, then the total turbulent burning velocity is expected to increase proportionally to the increase in the flame surface area caused by wrinkling. When the turbulence intensity is high enough such that the stretch due to hydrodynamics and flame curvature would influence the local premixed laminar burning velocity, then the actual laminar burning velocity (that is, flamelet consumption velocity) should reflect the influence of stretch. To address this issue, obtaining the knowledge of instantaneous flame front structures, flame brush characteristics, and burning velocities of premixed turbulent flames is necessary. Two axisymmetric Bunsen-type burners were used to produce premixed turbulent flames, and three optical measurement techniques were utilized: Particle image velocimetry to measure the turbulence statistics; Rayleigh scattering method to measure the temperature fields of premixed turbulent flames, and Mie scattering method to visualize the flame front contours of premixed turbulent flames. Three hydrocarbons (methane, ethane, and propane) were used as the fuel in the experiments. The turbulence was generated using different perforated plates mounted upstream of the burner exit. A series of comprehensive parameters including the thermal flame front thickness, characteristic flame height, mean flame brush thickness, mean volume of the turbulent flame region, two-dimensional flame front curvature, local flame front angle, two-dimensional flame surface density, wrinkled flame surface area, turbulent burning velocity, mean flamelet consumption velocity, mean turbulent flame stretch factor, mean turbulent Markstein length and number, and mean fuel consumption rate were systematically evaluated from the experimental data. The normalized preheat zone and reaction zone thicknesses decreased with increasing non-dimensional turbulence intensity in ultra-lean premixed turbulent flames under a constant equivalence ratio of 0.6, whereas they increased with increasing equivalence ratios from 0.6 to 1.0 under a constant bulk flow velocity. The normalized preheat zone and reaction zone thicknesses showed no overall trend with increasing non-dimensional longitudinal integral length scale. The normalized preheat zone and reaction zone thicknesses decreased by increasing the Karlovitz number, suggesting that increasing the total stretch rate is the controlling mechanism in the reduction of flame front thickness for the experimental conditions studied in this thesis. In general, the leading edge and half-burning surface turbulent burning velocities were enhanced with increasing equivalence ratio from lean to stoichiometric mixtures, whereas they decreased with increasing equivalence ratio for rich mixtures. These velocities were enhanced with increasing total turbulence intensity. The leading edge and half-burning surface turbulent burning velocities for lean/stoichiometric mixtures were observed to be smaller than that for rich mixtures. The mean turbulent flame stretch factor displayed a dependence on the equivalence ratio and turbulence intensity. Results show that the mean turbulent flame stretch factors for lean/stoichiometric and rich mixtures were not equal when the unstrained premixed laminar burning velocity, non-dimensional bulk flow velocity, non-dimensional turbulence intensity, and non-dimensional longitudinal integral length scale were kept constant.
Download or read book Experimental Investigation of the Dynamics and Structure of Lean premixed Turbulent Combustion written by Frank Tat Cheong Yuen and published by . This book was released on 2009 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent premixed propane/air and methane/air flames were studied using planar Rayleigh scattering and particle image velocimetry on a stabilized Bunsen type burner. The fuel-air equivalence ratio was varied from &phis; = 0:7 to 1.0 for propane flames, and from &phis; = 0:6 to 1.0 for methane flames. The non-dimensional turbulence intensity, u'/ SL (ratio of fluctuation velocity to laminar burning velocity), covered the range from 3 to 24, equivalent to conditions of corrugated flamelets and thin reaction zones regimes. Temperature gradients decreased with the increasing u'/SL and levelled off beyond u'/SL > 10 for both propane and methane flames. Flame front thickness increased slightly as u'/SL increased for both mixtures, although the thickness increase was more noticeable for propane flames, which meant the thermal flame front structure was being thickened. A zone of higher temperature was observed on the average temperature profile in the preheat zone of the flame front as well as some instantaneous temperature profiles at the highest u'/SL. Curvature probability density functions were similar to the Gaussian distribution at all u'/ SL for both mixtures and for all the flame sections. The mean curvature values decreased as a function of u'/ SL and approached zero. Flame front thickness was smaller when evaluated at flame front locations with zero curvature than that with curvature. Temperature gradients and FSD were larger when the flame curvature was zero. The combined thickness and FSD data suggest that the curvature effect is more dominant than that of the stretch by turbulent eddies during flame propagation. Integrated flame surface density for both propane and methane flames exhibited no dependance on u'/S L regardless of the FSD method used for evaluation. This observation implies that flame surface area may not be the dominant factor in increasing the turbulent burning velocity and the flamelet assumption may not be valid under the conditions studied. Dkappa term, the product of diffusivity evaluated at conditions studied and the flame front curvature, was a magnitude smaller than or the same magnitude as the laminar burning velocity.
Download or read book An Experimental Investigation of Combustion Products Through a Flat Laminar Pre mixed Hydrocarbon air Flame written by David Lee Brenchley and published by . This book was released on 1968 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulent Premixed Flames written by Nedunchezhian Swaminathan and published by Cambridge University Press. This book was released on 2011-04-25 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: A work on turbulent premixed combustion is important because of increased concern about the environmental impact of combustion and the search for new combustion concepts and technologies. An improved understanding of lean fuel turbulent premixed flames must play a central role in the fundamental science of these new concepts. Lean premixed flames have the potential to offer ultra-low emission levels, but they are notoriously susceptible to combustion oscillations. Thus, sophisticated control measures are inevitably required. The editors' intent is to set out the modeling aspects in the field of turbulent premixed combustion. Good progress has been made on this topic, and this cohesive volume contains contributions from international experts on various subtopics of the lean premixed flame problem.
Download or read book Experimental Investigation of Turbulent Hydrocarbon Diffusion Flames written by Y. M. Elkassabgi and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of Turbulent Scalar Flux in Premixed Flames written by Peter Anthony Markus Kalt and published by . This book was released on 1998 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of Flow Turbulence Effects on Premixed Methane air Flames written by Kenneth Owen Smith and published by . This book was released on 1978 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soot Formation in Combustion written by Henning Bockhorn and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 595 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soot Formation in Combustion represents an up-to-date overview. The contributions trace back to the 1991 Heidelberg symposium entitled "Mechanism and Models of Soot Formation" and have all been reedited by Prof. Bockhorn in close contact with the original authors. The book gives an easy introduction to the field for newcomers, and provides detailed treatments for the specialists. The following list of contents illustrates the topics under review:
Download or read book Fundamentals of Premixed Turbulent Combustion written by Andrei Lipatnikov and published by CRC Press. This book was released on 2012-10-24 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lean burning of premixed gases is considered to be a promising combustion technology for future clean and highly efficient gas turbine combustors. Yet researchers face several challenges in dealing with premixed turbulent combustion, from its nonlinear multiscale nature and the impact of local phenomena to the multitude of competing models. Filling
Download or read book Theoretical and Experimental Investigation of Turbulent Premixed Flames written by Medhat T. F. Azzazy and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Further Experimental Investigation of Hydrocarbon Turbulent Diffusion Flames written by D. J. Robson and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of the Dynamics and Blowoff Characteristics of Bluff body Stabilized 2D V Shaped Turbulent Premixed Flames with Different Gaseous Hydrocarbon Fuels written by Rishi Roy and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Study of Turbulent Premixed Combustion in V shaped Flames written by Sina Kheirkhah and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Characteristics of turbulent premixed flames were investigated experimentally. The investigations were performed using Mie scattering, Particle Image Velocimetry, Rayleigh scattering, and broad-band luminosity imaging techniques. Methane-air flames associated with a relatively wide range of turbulence intensities, fuel-air equivalence ratios, and mean bulk flow velocities were investigated. For a relatively moderate value of turbulence intensity, a new concept is introduced and utilized to provide a detailed description associated with interaction of turbulent flow and flame front. The concept pertains to reactants velocity estimated at the vicinity of the flame front and is referred to as the edge velocity. Specifically, it is shown that fluctuations of the flame front position are induced by fluctuations of the edge velocity. For a relatively wide range of turbulence intensity, several characteristics of turbulent premixed flames, namely, front topology, brush thickness, surface density, and consumption speeds are investigated. For the first time, several flame front structures are identified and studied. It is shown that, due to formation of these front structures, the regime of turbulent premixed combustion transitions from the regime of counter-gradient diffusion to that of the gradient diffusion. In addition to these, a comprehensive study is performed to investigate influence of flame configuration on several flame front characteristics. It is obtained that, although changing the flame configuration influences several flame characteristics, the trends associated with the effects of governing parameters on the characteristics are nearly independent of the flame configuration.
Download or read book Experimental Study of Premixed Flames in a Taylor Couette Combustor written by Vahid Vaezi and published by . This book was released on 2000 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamentals of Turbulent and Multiphase Combustion written by Kenneth Kuan-yun Kuo and published by John Wiley & Sons. This book was released on 2012-04-24 with total page 914 pages. Available in PDF, EPUB and Kindle. Book excerpt: Detailed coverage of advanced combustion topics from the author of Principles of combustion, Second Edition Turbulence, turbulent combustion, and multiphase reacting flows have become major research topics in recent decades due to their application across diverse fields, including energy, environment, propulsion, transportation, industrial safety, and nanotechnology. Most of the knowledge accumulated from this research has never been published in book form—until now. Fundamentals of Turbulent and Multiphase Combustion presents up-to-date, integrated coverage of the fundamentals of turbulence, combustion, and multiphase phenomena along with useful experimental techniques, including non-intrusive, laser-based measurement techniques, providing a firm background in both contemporary and classical approaches. Beginning with two full chapters on laminar premixed and non-premixed flames, this book takes a multiphase approach, beginning with more common topics and moving on to higher-level applications. In addition, Fundamentals of Turbulent and Multiphase Combustion: Addresses seven basic topical areas in combustion and multiphase flows, including laminar premixed and non-premixed flames, theory of turbulence, turbulent premixed and non-premixed flames, and multiphase flows Covers spray atomization and combustion, solid-propellant combustion, homogeneous propellants, nitramines, reacting boundary-layer flows, single energetic particle combustion, and granular bed combustion Provides experimental setups and results whenever appropriate Supported with a large number of examples and problems as well as a solutions manual, Fundamentals of Turbulent and Multiphase Combustion is an important resource for professional engineers and researchers as well as graduate students in mechanical, chemical, and aerospace engineering.
Download or read book Experimental Investigation and Spectral Modeling of Turbulent Combustion Noise from Premixed and Non Premixed Flames written by Christoph Jörg and published by . This book was released on 2015 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Global Consumption Speeds of Premixed Large Hydrocarbon Fuel Air Turbulent Bunsen Flames written by Aaron Jesse Fillo and published by . This book was released on 2016 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large-hydrocarbon fuels are used for ground and air transportation because of their high energy-density and will be for the foreseeable future. However, combustion of large-hydrocarbon fuels in a turbulent environment is poorly understood and difficult to predict. The turbulent flame speed, which is the velocity at which a flame front propagates through a turbulent fuel and air mixture, is a key property in turbulent combustion. The turbulent flame speed can be used as a model input parameter for tur- bulent combustion simulations. However, turbulent flame speeds for large-hydrocarbon fuels are largely unknown. These values are needed to improve combustion models and enhance understanding of the physics and chemistry that control turbulent combustion of large-hydrocarbon fuels. The objective of this study is to measure the turbulent flame speed of large-hydrocarbon fuels and to identify key physics in the turbulent combustion of these fuels. This is motivated by the use of the turbulent flame speeds in modeling combustion in practical devices and the significant use of large-hydrocarbons in these devices. This research has broad implications for society and industry; both the Federal Aviation Administration and gas turbine engine companies have called for research on the turbulent flame speeds of large-hydrocarbon fuels. The turbulent flame speed in this work is defined as the global consumption speed, and is measured for three fuels on a turbulent Bunsen burner. The Reynolds number, turbulence intensity, preheat temperature, and equivalent ratio can be independently controlled using the burner. A conventional Jet-A fuel, known as A2, is used as a reference because of its common use in commercial and military aviation. A2 is compared to bi-modal and quadra-modal blends referred to as C1 and C5, respectively. These fuels are selected as they have similar heat releases and laminar flame speeds. Time-averaged line of site images of OH*, CH*, and CO2* chemiluminescence are used to determine an the average flame front area. This flame area is used to determine the global consumption speed. The global consumption speed is measured for Reynolds number and equivalence ratio ranging between 5.000-10.000 and 0.7-1, respectively. Turbulence intensities are varied between 10% and 20% of the bulk flow velocity. The global consumption speed increases with turbulence intensity and Reynolds number for all fuels. Global consumption speeds for A2 and C5 match within 5% at all conditions. Conversely, the global consumption speed of C1 is up to 22% lower than A2 or C5. These results indicate the global consumption speed is sensitive to turbulent velocity fluctuations, bulk flow velocity, and fuel chemistry. These results together suggest the global consumption speed is additionally sensitive to flame stretch. Dimensional analysis is used to isolate and identify sensitivities of the global consumption speed to turbulent velocity fluctuations, bulk flow velocity, global stretch rate, and fuel chemistry. A clear sensitivity to fuel chemistry is observed and is affected by aromatic and alkane content. A2 and C5 have higher global consumptions speeds and increased stability; these fuels have shorter average hydrocarbon chain lengths and higher aro- matic content than C1. In addition, the global consumption speed is highly sensitive to turbulence intensity of the flow; the turbulent flame speed increases an average of 30% for all fuels between the minimum and maximum turbulence intensity cases. Results are attributed to a strong sensitivity of the global consumption speed to flame stretch and a strong coupling of turbulence and fuel chemistry effects. These conclusions agree with the available literature and provide a foundational understanding of the sensitivities of the global consumption speed for large-hydrocarbon fuels.
