Download or read book Suppression of Bluff body Stabilized Diffusion Flames written by Fumiaki Takahashi and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Extinction of Bluff Body Stabilized Diffusion Flames written by and published by . This book was released on 1998 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The extinction limits of a methane diffusion flame stabilized behind a backward-facing step in a small-scale wind tunnel were measured by injecting a fire-extinguishing agent (halon 1301) into the airflow. As the mean air velocity was increased, two distinct flame stabilization regimes were observed: rim-attached and wake-stabilized flames. For a fixed mean air velocity, the agent concentrations at extinction varied inversely with the agent injection period. As a result, the agent mass required to suppress the flame was nearly constant for a given air velocity, independent of the agent concentration and injection time. The critical agent mass increased with the mean air velocity.
Download or read book Suppression of Bluff Body Stabilized Pool Flames written by and published by . This book was released on 1999 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The suppression mechanisms of a nonpremixed flame stabilized behind a backward-facing step in a wind tunnel have been studied using a gaseous fire-extinguishing agent (Halon 1301, bromotrifluoromethane) into the airflow. Methane or JP-8 jet fuel was used to simulate a pool fire behind a clutter in the aircraft engine nacelle. The characteristic mixing time in the recirculation zone in the wake was measured by impulsively injecting salt water mist into the airflow and by determining a time constant for the exponential decay of the sodium D-line emission at high temperatures. For both methane and JP-8 fuels under relatively high air velocities, the dependence of the critical agent mole fraction at extinction on the injection period is predictable using the characteristic mixing time and the minimum agent mole fraction, which is a fuel property measurable by a steady-state cup-burner method.
Download or read book Stabilization of an Unconfined Flame by a Bluff Body written by Jean R. Hertzberg and published by . This book was released on 1986 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stabilization and Suppression of a Diffusion Flame Behind a Step written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using a flow visualization technique, stabilization and suppression of a nonpremixed methane flame behind a backward-facing step in a wind tunnel have been studied by impulsively injecting a gaseous fire-extinguishing agent into the airflow. As the mean air velocity was increased, two distinct flame stabilization and suppression regimes were observed: rim-attached wrinkled laminar flame and wake-stabilized turbulent flame. In the former, the flame detached immediately after agent arrival, while in the latter, the flame zone in the shear layer first became unstable, followed by the extinction of the flame in the recirculation zone.
Download or read book Joint Meeting of the U S Sections of the Combustion Institute Western States Central States Eastern States written by and published by . This book was released on 1999 with total page 954 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamentals and Technology of Combustion written by F El-Mahallawy and published by Elsevier. This book was released on 2002-07-10 with total page 863 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals and Technology of Combustion contains brief descriptions of combustion fundamental processes, followed by an extensive survey of the combustion research technology. It also includes mathematical combustion modeling of the processes covering mainly premixed and diffusion flames, where many chemical and physical processes compete in complex ways, for both laminar and turbulent flows. The combustion chemistry models that validate experimental data for different fuels are sufficiently accurate to allow confident predictions of the flame characteristics. This illustrates a unique bridge between combustion fundamentals and combustion technology, which provides a valuable technical reference for many engineers and scientists. Moreover, the book gives the reader sufficient background of basic engineering sciences such as chemistry, thermodynamics, heat transfer and fluid mechanics. The combustion research and mathematical models fit between small-scale laboratory burner flames, and large-scale industrial boilers, furnaces and combustion chambers. The materials have been collected from previous relevant research and some selected papers of the authors and co-workers, which have been presented mainly in different refereed journals, international conferences and symposia, thus providing a comprehensive collection. Furthermore, the book includes some of the many recent general correlations for the characteristics of laminar, turbulent, premixed and diffusion flames in an easily usable form. The authors believe that further progress in optimizing combustion performance and reducing polluting emissions can only be treated through understanding of combustion chemistry.
Download or read book Mechanisms of Flame Extinction for Bluff Body Stabilized Flames with Influences of Pressure Gradient Tailoring written by Anthony J. Morales and published by . This book was released on 2018 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flame extinction continues to hinder the performance of combustion technologies used in propulsion systems and power generating turbomachinery. Within these applications, there is a crucial need to improve energy output while minimizing harmful environmental impacts. Lean combustion helps attain these goals by minimizing fuel costs and reducing NO[subscript x] emissions. However, operating at lean conditions increases the likelihood of flame extinction; the flame becomes more susceptible to hydrodynamic instabilities which can induce global blowout and termination of the combustion process. The work in this thesis is focused on identifying the mechanisms of flame extinction and controlling these mechanisms via pressure gradient tailoring. This is accomplished within a premixed blow-down combustion facility utilizing a bluff body flame stabilizer where flame extinction is induced by removing the flow of fuel into the reactant mixture. CH* chemiluminescence imaging and high-speed particle imaging velocimetry (PIV) are used to determine the flame boundary and resolve the reacting flow field, respectively. The mechanisms of flame extinction are attributed to the changing vorticity dynamics within the flow field as the equivalence ratio is reduced, which will directly influence the strain rate experienced by the flame. To influence these vorticity dynamics, the test section walls are manipulated to alter the downstream pressure gradients. It is determined that increasing the magnitude of the downstream pressure gradient increases the growth of the strain rate and vorticity experienced by the flame.
Download or read book Effects of Combustion Chamber Blockage on Bluff Body Flame Stabilization written by James Roger Foster and published by Hassell Street Press. This book was released on 2021-09-09 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it. This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. To ensure a quality reading experience, this work has been proofread and republished using a format that seamlessly blends the original graphical elements with text in an easy-to-read typeface. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.
Download or read book A Detailed Investigation of Bluff Body Stabilized Flames Postprint written by and published by . This book was released on 2007 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reduced Order Models (ROMs) and Computational Fluid Dynamics (CFD) codes are tools used to predict the extinction of flames behind bluff bodies. Accurate prediction of these models and codes is predicated on their validation with experimental data. This paper describes detailed experiments to obtain validation data for bluff body stabilized flames over a wide range of conditions. Included are non-reacting data from CFD and LDV, lean blowout and high speed images for three different flame holders. In our previous paper (Kiel 2006) it was asserted that the large vortices were a major driver of extinction. Those assertions are further supported here. It is concluded that the vortex dynamics and not geometry is the dominant mechanism for bluff body flame extinction. This conclusion is supported by the lean blowout data, by the high speed images and reference data from NACA.
Download or read book Thermal Theory of Bluff Body Flame Stabilization written by Milan K. Jovanivic and published by . This book was released on 1957 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemistry and Turbulence Effects in Bluff body Stabilized Flames written by J. C. Pan and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flame Extinction Dynamics of Lean Premixed Bluff body Stabilized Flames written by Marissa Kelley MacDonald and published by . This book was released on 2014 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulation of Bluff body Stabilized Flames written by Farzin Jalilalghadr and published by . This book was released on 2007 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct numerical simulation (DNS) is used to study reacting and non-reacting bluff-body stabilized flows. Three fuel-to-air velocity ratios were considered. The results show that three types of flow fields can be identified. For the fuel-to-air velocity ratio of 0:84, the flow field is dominated by the reverse flow of the coflowing air. The jet does not penetrate through the reverse flow, and two stagnation points are formed on the centerline, where the jet and air stagnate. The downstream flow field is similar to a wake flow, and therefore this flow is referred to as a bluff-body dominant flow. For the fuel-to-air velocity ratio of 1:4, the flow field is neither dominated by the jet nor the coflowing air and is referred to as an intermittent flow. For the fuel-to-air velocity ratio of 2:8, the jet penetrates through the reverse flow and no stagnation point is formed. The flow field is similar to that of a pure jet, therefore this flow is referred to as a jet dominant flow. In all cases, the coflowing air converges towards the centerline and forms a recirculation zone that extends to approximately one bluff-body diameter downstream. For the reacting flow, the methane combustion is modeled via a global, 1-step kinetic mechanism. The main effects of combustion on the flow field are an increase in the length of the recirculation zone, and a decrease in the velocity fluctuations. Based on the three velocity ratios, three types of flames are produced. For the velocity ratio of 0:84, a short mushroom shaped flame is produced near the fuel stagnation point. For the velocity ratio of 1:4, a medium length flame is produced in the shear layer region between the fuel and air. The flame is anchored in the recirculation zone, and extends downstream of the bluff-body. For the velocity ratio of 2:8, a long flame is produced near the centerline and is also anchored in the recirculation zone. All three flames are stabilized between the coflowing air and the jet, where the strain-rates are low, and the mixture fraction is near the stoichiometric value for methane combustion.
Download or read book Theory of Bluff Body Flame Stabilization Emphasizing the Initial Interaction Between Cool Combustible and Hot Combustion Products written by Hui-Ming Fu and published by . This book was released on 1961 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bluff Body Flame Stabilization with Liquid Fuel Present on the Flameholder written by Richard Michael Gross and published by . This book was released on 1972 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
