Author: Grant Douglas Swenson
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 157

Get Book Here

Book Description

Author: Timothy C. Lieuwen
Publisher: AIAA (American Institute of Aeronautics & Astronautics)
ISBN:
Category : Science
Languages : en
Pages : 688

Get Book Here

Book Description
This book offers gas turbine users and manufacturers a valuable resource to help them sort through issues associated with combustion instabilities. In the last ten years, substantial efforts have been made in the industrial, governmental, and academic communities to understand the unique issues associated with combustion instabilities in low-emission gas turbines. The objective of this book is to compile these results into a series of chapters that address the various facets of the problem. The Case Studies section speaks to specific manufacturer and user experiences with combustion instabilities in the development stage and in fielded turbine engines. The book then goes on to examine The Fundamental Mechanisms, The Combustor Modeling, and Control Approaches.

Author: Johannes Janicka
Publisher: Springer Science & Business Media
ISBN: 9400753209
Category : Technology & Engineering
Languages : en
Pages : 495

Get Book Here

Book Description
With regard to both the environmental sustainability and operating efficiency demands, modern combustion research has to face two main objectives, the optimization of combustion efficiency and the reduction of pollutants. This book reports on the combustion research activities carried out within the Collaborative Research Center (SFB) 568 “Flow and Combustion in Future Gas Turbine Combustion Chambers” funded by the German Research Foundation (DFG). This aimed at designing a completely integrated modeling and numerical simulation of the occurring very complex, coupled and interacting physico-chemical processes, such as turbulent heat and mass transport, single or multi-phase flows phenomena, chemical reactions/combustion and radiation, able to support the development of advanced gas turbine chamber concepts

Author: Fabien Dupuy (docteur en physique).)
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

Get Book Here

Book Description
Increasingly stringent regulations as well as environmental concerns have lead gas turbine powered engine manufacturers to develop the current generation of combustors, which feature lower than ever fuel consumption and pollutant emissions. However, modern combustor designs have been shown to be prone to combustion instabilities, where the coupling between acoustics of the combustor and the flame results in large pressure oscillations and vibrations within the combustion chamber. These instabilities can cause structural damages to the engine or even lead to its destruction. At the same time, considerable developments have been achieved in the numerical simulation domain, and Computational Fluid Dynamics (CFD) has proven capable of capturing unsteady flame dynamics and combustion instabilities for aforementioned engines. Still, even with the current large and fast increasing computing capabilities, time remains the key constraint for these high fidelity yet computationally intensive calculations. Typically, covering the entire range of operating conditions for an industrial engine is still out of reach. In that respect, low order models exist and can be efficient at predicting the occurrence of combustion instabilities, provided an adequate modeling of the flame/acoustics interaction as appearing in the system is available. This essential piece of information is usually recast as the so called Flame Transfer Function (FTF) relating heat release rate fluctuations to velocity fluctuations at a given point. One way to obtain this transfer function is to rely on analytical models, but few exist for turbulent swirling flames. Another way consists in performing costly experiments or numerical simulations, negating the requested fast prediction capabilities. This thesis therefore aims at providing fast, yet reliable methods to allow for low order combustion instabilities modeling. In that context, understanding the underlying mechanisms of swirling flame acoustic response is also targeted. To address this issue, a novel hybrid approach is first proposed based on a reduced set of high fidelity simulations that can be used to determine input parameters of an analytical model used to express the FTF of premixed swirling flames. The analytical model builds on previous works starting with a level-set description of the flame front dynamics while also accounting for the acoustic-vorticity conversion through a swirler. For such a model, validation is obtained using reacting stationary and pulsed numerical simulations of a laboratory scale premixed swirl stabilized flame. The model is also shown to be able to handle various perturbation amplitudes. At last, 3D high fidelity simulations of an industrial gas turbine powered by a swirled spray flame are performed to determine whether a combustion instability observed in experiments can be predicted using numerical analysis. To do so, a series of forced simulations is carried out in en effort to highlight the importance of the two-phase flow flame response evaluation. In that case, sensitivity to reference velocity perturbation probing positions as well as the amplitude and location of the acoustic perturbation source are investigated. The analytical FTF model derived in the context of a laboratory premixed swirled burner is furthermore gauged in this complex case. Results show that the unstable mode is predicted by the acoustic analysis, but that the flame model proposed needs further improvements to extend its applicability range and thus provide data relevant to actual aero-engines.

Author: Dan Zhao
Publisher: Academic Press
ISBN: 0323899188
Category : Technology & Engineering
Languages : en
Pages : 1145

Get Book Here

Book Description
Thermoacoustic Combustion Instability Control: Engineering Applications and Computer Codes provides a unique opportunity for researchers, students and engineers to access recent developments from technical, theoretical and engineering perspectives. The book is a compendium of the most recent advances in theoretical and computational modeling and the thermoacoustic instability phenomena associated with multi-dimensional computing methods and recent developments in signal-processing techniques. These include, but are not restricted to a real-time observer, proper orthogonal decomposition (POD), dynamic mode decomposition, Galerkin expansion, empirical mode decomposition, the Lattice Boltzmann method, and associated numerical and analytical approaches. The fundamental physics of thermoacoustic instability occurs in both macro- and micro-scale combustors. Practical methods for alleviating common problems are presented in the book with an analytical approach to arm readers with the tools they need to apply in their own industrial or research setting. Readers will benefit from practicing the worked examples and the training provided on computer coding for combustion technology to achieve useful results and simulations that advance their knowledge and research. Focuses on applications of theoretical and numerical modes with computer codes relevant to combustion technology Includes the most recent modeling and analytical developments motivated by empirical experimental observations in a highly visual way Provides self-contained chapters that include a comprehensive, introductory section that ensures any readers new to this topic are equipped with required technical terms

Author: Bart Merci
Publisher: Springer Science & Business Media
ISBN: 9400714092
Category : Technology & Engineering
Languages : en
Pages : 180

Get Book Here

Book Description
This book reflects the outcome of the 1st International Workshop on Turbulent Spray Combustion held in 2009 in Corsica (France). The focus is on reporting the progress of experimental and numerical techniques in two-phase flows, with emphasis on spray combustion. The motivation for studies in this area is that knowledge of the dominant phenomena and their interactions in such flow systems is essential for the development of predictive models and their use in combustor and gas turbine design. This necessitates the development of accurate experimental methods and numerical modelling techniques. The workshop aimed at providing an opportunity for experts and young researchers to present the state-of-the-art, discuss new developments or techniques and exchange ideas in the areas of experimentations, modelling and simulation of reactive multiphase flows. The first two papers reflect the contents of the invited lectures, given by experts in the field of turbulent spray combustion. The first concerns computational issues, while the second deals with experiments. These lectures initiated very interesting and interactive discussions among the researchers, further pursued in contributed poster presentations. Contributions 3 and 4 focus on some aspects of the impact of the interaction between fuel evaporation and combustion on spray combustion in the context of gas turbines, while the final article deals with the interaction between evaporation and turbulence.

Author: James Fayiah Willie
Publisher: Cuvillier Verlag
ISBN: 3736940017
Category : Technology & Engineering
Languages : en
Pages : 186

Get Book Here

Book Description
The main objective of this thesis is to analyze combustion instabilities in a matrix burner. The various tools that exist for analyzing thermoacoustic instabilities are applied to the matrix burner with multiple flames. The principal goals are to determine the primary causes of combustion instabilities in the burner and to explore ways of controlling such instabilities in order to prevent damage to the burner. To achieve these goals, the stability map of the burner obtained from measurements is analyzed. This is followed by the analysis of the aerodynamics of the cold flow using CFD. Results obtained from CFD are validated with PIV and LDA results from measurements. Critical are the centerline axial velocity inside the combustion chamber and the recirculation zones on the walls of the combustion chamber and those between the various slots of the matrix burner. Cold flow simulations are followed by reactive flow simulations for both gaseous and liquid fuels. A detailed atomization model is developed for the liquid fuel case from experimental data. Two combustion models, namely, the combined finite rate/eddy dissipation model and the finite rate chemistry model are compared in the CFD simulations of combustion instabilities and validation with measurements are done. The latter is chosen over the former because it accounts for chemistry and it is not numerically dissipative. Two CFD softwares, Fluent and CFX are also compared to determine which is better at capturing acoustics. System identification using CFD is used to determine the flame transfer function and the acoustic transfer matrix. This is followed by the use of acoustic forcing and fuel modulation on the primary and pilot in order to limit the amplitude of the instabilities inside the matrix burner combustor. The 1D acoustic network is used to determine the longitudinal eigenmodes of the matrix burner. This is followed by the use of 3D finite element method (FEM) and fluid-structure interaction (FSI) to determine whether a coupling exist between the fluid and structure of the matrix burner combustor and vice versa. Finally, Full harmonic analysis is performed for the rectangular combustor and the results obtained are validated with analytical results. This is followed by the 3D structure modal analysis of the full matrix burner test rig.

Author: Paul Palies
Publisher: Academic Press
ISBN: 0128199970
Category : Technology & Engineering
Languages : en
Pages : 402

Get Book Here

Book Description
Stabilization and Dynamic of Premixed Swirling Flames: Prevaporized, Stratified, Partially, and Fully Premixed Regimes focuses on swirling flames in various premixed modes (stratified, partially, fully, prevaporized) for the combustor, and development and design of current and future swirl-stabilized combustion systems. This includes predicting capabilities, modeling of turbulent combustion, liquid fuel modeling, and a complete overview of stabilization of these flames in aeroengines. The book also discusses the effects of the operating envelope on upstream fresh gases and the subsequent impact of flame speed, combustion, and mixing, the theoretical framework for flame stabilization, and fully lean premixed injector design. Specific attention is paid to ground gas turbine applications, and a comprehensive review of stabilization mechanisms for premixed, partially-premixed, and stratified premixed flames. The last chapter covers the design of a fully premixed injector for future jet engine applications. Features a complete view of the challenges at the intersection of swirling flame combustors, their requirements, and the physics of fluids at work Addresses the challenges of turbulent combustion modeling with numerical simulations Includes the presentation of the very latest numerical results and analyses of flashback, lean blowout, and combustion instabilities Covers the design of a fully premixed injector for future jet engine applications

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 10

Get Book Here

Book Description
It is well known that the two key elements for achieving low emissions and high performance in a gas turbine combustor are to simultaneously establish (1) a lean combustion zone for maintaining low NO(subscript x) emissions and (2) rapid mixing for good ignition and flame stability. However, these requirements, when coupled with the short combustor lengths used to limit the residence time for NO formation typical of advanced gas turbine combustors, can lead to problems regarding unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions, as well as the occurrence of combustion instabilities. The concurrent development of suitable analytical and numerical models that are validated with experimental studies is important for achieving this objective. A major benefit of the present research will be to provide for the first time an experimentally verified model of emissions and performance of gas turbine combustors. The present study represents a coordinated effort between industry, government and academia to investigate gas turbine combustion dynamics. Specific study areas include development of advanced diagnostics, definition of controlling phenomena, advancement of analytical and numerical modeling capabilities, and assessment of the current status of our ability to apply these tools to practical gas turbine combustors. The present work involves four tasks which address, respectively, (1) the development of a fiber-optic probe for fuel-air ratio measurements, (2) the study of combustion instability using laser-based diagnostics in a high pressure, high temperature flow reactor, (3) the development of analytical and numerical modeling capabilities for describing combustion instability which will be validated against experimental data, and (4) the preparation of a literature survey and establishment of a data base on practical experience with combustion instability.

Author: B. Sekar
Publisher:
ISBN:
Category :
Languages : en
Pages : 16

Get Book Here

Book Description
This paper describes the development and application of a combined detailed three-dimensional large eddy simulation (LES) and one-dimensional analysis tool to predict and actively control combustion-driven dynamic instabilities in gas turbine combustors. The integration of detailed finite-rate kinetics into LES and use of In-situ Adaptive Tabulation (ISAT) to efficiently calculate multi-species finite-rate kinetics in LES along with the use of global kinetics in the one-dimensional analysis tool was demonstrated. The results showed that LES can be effectively used to simulate complex reacting flows in gas turbine combustors and to identify regions of combustion instabilities. The results also showed that the one-dimensional combustor analysis with global kinetics can then be used both to capture the combustor unstable modes of the predicted regions of instabilities and to actively control these instabilities. In particular, the results demonstrated that by modulating the primary fuel injection rates and the time-lag between the instant of fuel-air mixture injection and heat release, damping out the instabilities may be achieved.