Download or read book Calculations of Turbulent Reacting Flows Using PDF Methods written by David Henry Rowinski and published by . This book was released on 2013 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents applications of the probability density function (PDF) method to several recently-developed turbulent flows, and the implementation and assessment of several sub-models. A series of lean piloted premixed jet flames (in order of lowest to highest jet bulk velocity: PM1-50, PM1-100, PM1150, and PM1-200) is first studied using a Reynolds-Averaged Navier-Stokes (RANS) based PDF method. These calculations use diagnostic testing and thorough parametric studies of models to show that the standard models overpredict the reaction rate in the flames PM1-150 and PM1-200. The nature of the combustion in these flames is examined through comparison to simpler combustion models, and it is found to be similar to laminar non-premixed flames. These same flames are then investigated further using both RANS-PDF and the recently developed Large Eddy Simulation (LES) PDF method. Simple models for molecular diffusion and combustion are tested and implemented in the RANS-PDF calculations. In the LES-PDF calculations, the effects of differential diffusion and the mixing model constant, C M, are both examined, and the calculations are found to be very sensitive to the value of C M . This study yields substantially improved calculations of all the flames. In particular, the study of C M shows strong evidence that larger values of C M are necessary for flames PM1-150 and PM1-200. The modeling of molecular mixing is investigated further through a study of a non-reacting turbulent jet flow with three inflowing streams. This study presents the unique opportunity to compare the scalar dissipation rate and conditional diffusion from the calculations to experimental data. In the RANS-PDF calculations of this flow, three classic mixing models are evaluated. The joint scalar PDF's are very sensitive to the choice of mixing model and show a wide variability from the measurements. Only the Euclidean Minimum Spanning Tree (EMST) produces compositions which lie very close to the slow manifold identified in the experimental work. LES calculations of the same flow are performed, and the dissipation rate and conditional diffusion are calculated. The resolved scalar dissipation rate is found to be in good agreement with the experimental data, but depends strongly on the resolution; the total dissipation rate from the RANS-PDF and LES calculations indicates significantly larger scalar dissipation rates than those measured experimentally. Lastly, LES-PDF calculations of the same flow yield joint-PDF's in very good agreement with the experimental data, and are far-improved from those of any mixing model studied with RANS-PDF. The attenuation of variance production model is introduced for LES-PDF and tested in this flow. This new model results in an additional dissipation of scalar variance and yields calculations of improved accuracy on coarse grids.
Download or read book An Introduction to Turbulent Reacting Flows written by R. S. Cant and published by Imperial College Press. This book was released on 2008 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides physical intuition and key entries to the body of literature. This book includes historical perspective of the theories.
Download or read book Turbulent Reacting Flows written by R. W. Bilger and published by Springer. This book was released on 1980 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulent Reactive Flows written by R. Borghi and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 958 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent reactive flows are of common occurrance in combustion engineering, chemical reactor technology and various types of engines producing power and thrust utilizing chemical and nuclear fuels. Pollutant formation and dispersion in the atmospheric environment and in rivers, lakes and ocean also involve interactions between turbulence, chemical reactivity and heat and mass transfer processes. Considerable advances have occurred over the past twenty years in the understanding, analysis, measurement, prediction and control of turbulent reactive flows. Two main contributors to such advances are improvements in instrumentation and spectacular growth in computation: hardware, sciences and skills and data processing software, each leading to developments in others. Turbulence presents several features that are situation-specific. Both for that reason and a number of others, it is yet difficult to visualize a so-called solution of the turbulence problem or even a generalized approach to the problem. It appears that recognition of patterns and structures in turbulent flow and their study based on considerations of stability, interactions, chaos and fractal character may be opening up an avenue of research that may be leading to a generalized approach to classification and analysis and, possibly, prediction of specific processes in the flowfield. Predictions for engineering use, on the other hand, can be foreseen for sometime to come to depend upon modeling of selected features of turbulence at various levels of sophistication dictated by perceived need and available capability.
Download or read book Comparison of PDF and Moment Closure Methods in the Modeling of Turbulent Reacting Flows written by Andrew T. Norris and published by . This book was released on 1994 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: In modeling turbulent reactive flows, Probability Density Function (PDF) methods have an advantage over the more traditional moment closure schemes in that the PDF formulation treats the chemical reaction source terms exactly, while moment closure methods are required to model the mean reaction rate. The common model used is the laminar chemistry approximation, where the effects of turbulence on the reaction are assumed negligible. For flows with low turbulence levels and fast chemistry, the difference between the two methods can be expected to be small. However for flows with finite rate chemistry and high turbulence levels, significant errors can be expected in the moment closure method. In this paper, the ability of the PDF method and the moment closure scheme to accurately model a turbulent reacting flow is tested.
Download or read book Comparison of PDF and Moment Closure Methods in the Modeling of Turbulent Reacting Flows written by and published by . This book was released on 1994 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Statistical Mechanics of Turbulent Flows written by Stefan Heinz and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: The simulation of technological and environmental flows is very important for many industrial developments. A major challenge related to their modeling is to involve the characteristic turbulence that appears in most of these flows. The traditional way to tackle this question is to use deterministic equations where the effects of turbulence are directly parametrized, i. e. , assumed as functions of the variables considered. However, this approach often becomes problematic, in particular if reacting flows have to be simulated. In many cases, it turns out that appropriate approximations for the closure of deterministic equations are simply unavailable. The alternative to the traditional way of modeling turbulence is to construct stochastic models which explain the random nature of turbulence. The application of such models is very attractive: one can overcome the closure problems that are inherent to deterministic methods on the basis of relatively simple and physically consistent models. Thus, from a general point of view, the use of stochastic methods for turbulence simulations seems to be the optimal way to solve most of the problems related to industrial flow simulations. However, it turns out that this is not as simple as it looks at first glance. The first question concerns the numerical solution of stochastic equations for flows of environmental and technological interest. To calculate industrial flows, 3 one often has to consider a number of grid cells that is of the order of 100 .
Download or read book Computational Models for Turbulent Reacting Flows written by Rodney O. Fox and published by Cambridge University Press. This book was released on 2003-10-30 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Table of contents
Download or read book Parallel Numerical Computation of Turbulent Reacting Flows Following a Lagrangian PDF Method and Using Replicated Workers Coordination Abstraction written by Francois Le Droff and published by . This book was released on 1999 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Application of PDF Methods to Compressible Turbulent Reacting Flows written by Bertrand Delarue and published by . This book was released on 1997 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A PDF Closure Model for Compressible Turbulent Chemically Reacting Flows written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-17 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the proposed research project was the analysis of single point closures based on probability density function (pdf) and characteristic functions and the development of a prediction method for the joint velocity-scalar pdf in turbulent reacting flows. Turbulent flows of boundary layer type and stagnation point flows with and without chemical reactions were be calculated as principal applications. Pdf methods for compressible reacting flows were developed and tested in comparison with available experimental data. The research work carried in this project was concentrated on the closure of pdf equations for incompressible and compressible turbulent flows with and without chemical reactions. Kollmann, W. Unspecified Center BOUNDARY LAYER COMBUSTION; COMPRESSIBLE FLOW; PREDICTION ANALYSIS TECHNIQUES; PROBABILITY THEORY; REACTING FLOW; TURBULENT FLOW; FLAME PROPAGATION; INCOMPRESSIBLE FLOW; STAGNATION POINT...
Download or read book An Assessment of PDF Versus Finite volume Methods for Turbulent Reacting Flow Calculations written by A. T. Hsu and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory and Modeling of Dispersed Multiphase Turbulent Reacting Flows written by Lixing Zhou and published by Butterworth-Heinemann. This book was released on 2018-01-25 with total page 343 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theory and Modeling of Dispersed Multiphase Turbulent Reacting Flows gives a systematic account of the fundamentals of multiphase flows, turbulent flows and combustion theory. It presents the latest advances of models and theories in the field of dispersed multiphase turbulent reacting flow, covering basic equations of multiphase turbulent reacting flows, modeling of turbulent flows, modeling of multiphase turbulent flows, modeling of turbulent combusting flows, and numerical methods for simulation of multiphase turbulent reacting flows, etc. The book is ideal for graduated students, researchers and engineers in many disciplines in power and mechanical engineering. - Provides a combination of multiphase fluid dynamics, turbulence theory and combustion theory - Covers physical phenomena, numerical modeling theory and methods, and their applications - Presents applications in a wide range of engineering facilities, such as utility and industrial furnaces, gas-turbine and rocket engines, internal combustion engines, chemical reactors, and cyclone separators, etc.
Download or read book Application of a Pdf Method to Compressible Turbulent Reacting Flows written by A. T. Hsu and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulent Combustion Modeling written by Tarek Echekki and published by Springer Science & Business Media. This book was released on 2010-12-25 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent combustion sits at the interface of two important nonlinear, multiscale phenomena: chemistry and turbulence. Its study is extremely timely in view of the need to develop new combustion technologies in order to address challenges associated with climate change, energy source uncertainty, and air pollution. Despite the fact that modeling of turbulent combustion is a subject that has been researched for a number of years, its complexity implies that key issues are still eluding, and a theoretical description that is accurate enough to make turbulent combustion models rigorous and quantitative for industrial use is still lacking. In this book, prominent experts review most of the available approaches in modeling turbulent combustion, with particular focus on the exploding increase in computational resources that has allowed the simulation of increasingly detailed phenomena. The relevant algorithms are presented, the theoretical methods are explained, and various application examples are given. The book is intended for a relatively broad audience, including seasoned researchers and graduate students in engineering, applied mathematics and computational science, engine designers and computational fluid dynamics (CFD) practitioners, scientists at funding agencies, and anyone wishing to understand the state-of-the-art and the future directions of this scientifically challenging and practically important field.
Download or read book LES PDF Approach for Turbulent Reacting Flows written by Pratik Prakash Donde and published by . This book was released on 2012 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: The probability density function (PDF) approach is a powerful technique for large eddy simulation (LES) based modeling of turbulent reacting flows. In this approach, the joint-PDF of all reacting scalars is estimated by solving a PDF transport equation, thus providing detailed information about small-scale correlations between these quantities. The objective of this work is to further develop the LES/PDF approach for studying flame stabilization in supersonic combustors, and for soot modeling in turbulent flames.
Download or read book Les DNS and Rans for the Analysis of High Speed Turbulent Reacting Flows written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-18 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this research is to continue our efforts in advancing the state of knowledge in large eddy simulation (LES), direct numerical simulation (DNS), and Reynolds averaged Navier Stokes (RANS) methods for the computational analysis of high-speed reacting turbulent flows. In the second phase of this work, covering the period 1 Sep. 1993 - 1 Sep. 1994, we have focused our efforts on two research problems: (1) developments of 'algebraic' moment closures for statistical descriptions of nonpremixed reacting systems, and (2) assessments of the Dirichlet frequency in presumed scalar probability density function (PDF) methods in stochastic description of turbulent reacting flows. This report provides a complete description of our efforts during this past year as supported by the NASA Langley Research Center under Grant NAG1-1122. Givi, Peyman and Taulbee, Dale B. and Adumitroaie, Virgil and Sabini, George J. and Shieh, Geoffrey S. Unspecified Center COMPUTATIONAL FLUID DYNAMICS; PROBABILITY DENSITY FUNCTIONS; REACTING FLOW; STOCHASTIC PROCESSES; TURBULENT FLOW; DIRICHLET PROBLEM; HIGH SPEED; MIXING LAYERS (FLUIDS); NAVIER-STOKES EQUATION; VORTICES...
