Combustion Dynamics and Control for Ultra Low Emissions in Aircraft Gas-Turbine Engines

Combustion Dynamics and Control for Ultra Low Emissions in Aircraft Gas-Turbine Engines
Author: John C. Delaat
Publisher: BiblioGov
Total Pages: 24
Release: 2013-06
Genre:
ISBN: 9781289111984

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Future aircraft engines must provide ultra-low emissions and high efficiency at low cost while maintaining the reliability and operability of present day engines. The demands for increased performance and decreased emissions have resulted in advanced combustor designs that are critically dependent on efficient fuel/air mixing and lean operation. However, all combustors, but most notably lean-burning low-emissions combustors, are susceptible to combustion instabilities. These instabilities are typically caused by the interaction of the fluctuating heat release of the combustion process with naturally occurring acoustic resonances. These interactions can produce large pressure oscillations within the combustor and can reduce component life and potentially lead to premature mechanical failures. Active Combustion Control which consists of feedback-based control of the fuel-air mixing process can provide an approach to achieving acceptable combustor dynamic behavior while minimizing emissions, and thus can provide flexibility during the combustor design process. The NASA Glenn Active Combustion Control Technology activity aims to demonstrate active control in a realistic environment relevant to aircraft engines by providing experiments tied to aircraft gas turbine combustors. The intent is to allow the technology maturity of active combustion control to advance to eventual demonstration in an engine environment. Work at NASA Glenn has shown that active combustion control, utilizing advanced algorithms working through high frequency fuel actuation, can effectively suppress instabilities in a combustor which emulates the instabilities found in an aircraft gas turbine engine. Current efforts are aimed at extending these active control technologies to advanced ultra-low-emissions combustors such as those employing multi-point lean direct injection.

Reduced-order Modeling and Active Control of Dry-low-emission Combustion

Reduced-order Modeling and Active Control of Dry-low-emission Combustion
Author: Tongxun Yi
Publisher:
Total Pages: 179
Release: 2007
Genre:
ISBN: 9780549023111

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This dissertation is a complementary experimental and theoretical investigation of combustion instability and lean blowout (LBO) in dry-low-emission (DLE) gas turbine engines, aiming to understand the fundamental mechanisms and shed light on active combustion control.

Combustion Instabilities in Gas Turbine Engines

Combustion Instabilities in Gas Turbine Engines
Author: Timothy C. Lieuwen
Publisher: AIAA (American Institute of Aeronautics & Astronautics)
Total Pages: 688
Release: 2005
Genre: Science
ISBN:

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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.

Emissions, Combustion Dynamics, and Control of a Multiple Swirl Combustor

Emissions, Combustion Dynamics, and Control of a Multiple Swirl Combustor
Author:
Publisher:
Total Pages:
Release: 2004
Genre:
ISBN:

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To achieve single digit NOx emission from gas turbine combustors and prevent the combustion dynamics encountered in Lean Premixed Combustion, it is essential to understand the correlations among emission characteristics, combustion dynamics, and dynamics and characteristics of swirling flow field. The focus of this dissertation is to investigate the emission characteristics and combustion dynamics of multiple swirl dump combustors either in premixing or non-premixed combustion (e.g. Lean Direct Injection), and correlate these combustion characteristics (emissions, combustion instability and lean flammability) to the fluids dynamics (flow structures and its evolution). This study covers measurement of velocity flow field, temperature field, and combustion under effects of various parameters, including inlet flow Reynolds number, inlet air temperature, swirl configurations, downstream exhaust nozzle contraction ratios, length of mixing tube. These parameters are tested in both liquid and gaseous fuel combustions. Knowledge obtained through this comprehensive study is applied to passive and active controls for improving gas turbine combustion performance in the aid of novel sensor and actuator technologies. Emissions and combustion characteristics are shown closely related to the shape and size of central recirculation zone (CRZ), the mean and turbulence velocity and strain rate, and dynamics of large vortical structures. The passive controls, mostly geometry factors, affect the combustion characteristics and emissions through their influences on flow fields, and consequently temperature and radical fields. Air assist, which is used to adjust the momentum of fuel spray, is effective in reducing NOx and depress combustion oscillation without hurting LBO. Fuel distribution/split is also one important factor for achieving low NOx emission and control of combustion dynamics. The dynamics of combustion, including flame oscillations close to LBO and acoustic combustion instability, can be characterized by OH*/CH* radical oscillations and phase-locked chemiluminescence imaging. The periodic fluctuation of jet velocity and formation of large vortical structures within CRZ are responsible for combustion instability in multiple swirl combustors.

Gas Turbine Combustion

Gas Turbine Combustion
Author: Arthur H. Lefebvre
Publisher: CRC Press
Total Pages: 560
Release: 2010-04-26
Genre: Science
ISBN: 1420086057

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Reflecting the developments in gas turbine combustion technology that have occurred in the last decade, Gas Turbine Combustion: Alternative Fuels and Emissions, Third Edition provides an up-to-date design manual and research reference on the design, manufacture, and operation of gas turbine combustors in applications ranging from aeronautical to po

Combustion for Power Generation and Transportation

Combustion for Power Generation and Transportation
Author: Avinash Kumar Agarwal
Publisher: Springer
Total Pages: 448
Release: 2017-01-20
Genre: Technology & Engineering
ISBN: 981103785X

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This research monograph presents both fundamental science and applied innovations on several key and emerging technologies involving fossil and alternate fuel utilization in power and transport sectors from renowned experts in the field. Some of the topics covered include: autoignition in laminar and turbulent nonpremixed flames; Langevin simulation of turbulent combustion; lean blowout (LBO) prediction through symbolic time series analysis; lasers and optical diagnostics for next generation IC engine development; exergy destruction study on small DI diesel engine; and gasoline direct injection. The book includes a chapter on carbon sequestration and optimization of enhanced oil and gas recovery. The contents of this book will be useful to researchers and professionals working on all aspects on combustion.

Gas Turbine Engineering Handbook

Gas Turbine Engineering Handbook
Author: Meherwan P. Boyce
Publisher: Elsevier
Total Pages: 956
Release: 2017-09-01
Genre: Mathematics
ISBN: 0080456898

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The Gas Turbine Engineering Handbook has been the standard for engineers involved in the design, selection, and operation of gas turbines. This revision includes new case histories, the latest techniques, and new designs to comply with recently passed legislation. By keeping the book up to date with new, emerging topics, Boyce ensures that this book will remain the standard and most widely used book in this field. The new Third Edition of the Gas Turbine Engineering Hand Book updates the book to cover the new generation of Advanced gas Turbines. It examines the benefit and some of the major problems that have been encountered by these new turbines. The book keeps abreast of the environmental changes and the industries answer to these new regulations. A new chapter on case histories has been added to enable the engineer in the field to keep abreast of problems that are being encountered and the solutions that have resulted in solving them. Comprehensive treatment of Gas Turbines from Design to Operation and Maintenance. In depth treatment of Compressors with emphasis on surge, rotating stall, and choke; Combustors with emphasis on Dry Low NOx Combustors; and Turbines with emphasis on Metallurgy and new cooling schemes. An excellent introductory book for the student and field engineers A special maintenance section dealing with the advanced gas turbines, and special diagnostic charts have been provided that will enable the reader to troubleshoot problems he encounters in the field The third edition consists of many Case Histories of Gas Turbine problems. This should enable the field engineer to avoid some of these same generic problems

Combustion Instability Modeling and Analysis

Combustion Instability Modeling and Analysis
Author:
Publisher:
Total Pages: 10
Release: 1995
Genre:
ISBN:

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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.

Combustion in Advanced Gas Turbine Systems

Combustion in Advanced Gas Turbine Systems
Author: I. E. Smith
Publisher: Elsevier
Total Pages: 415
Release: 2014-05-17
Genre: Technology & Engineering
ISBN: 1483186369

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Cranfield International Symposium Series, Volume 10: Combustion in Advanced Gas Turbine Systems covers the proceedings of an International Propulsion Symposium, held at the College of Aeronautics in Cranfield in April 1967. The book focuses on the processes, methodologies, reactions, and transformations involved in chemical combustion. The selection first takes a look at the design considerations in advanced gas turbine combustion chambers, combustion in industrial gas turbines, and combustion development on the Rolls-Royce Spey engine. Discussions focus on mechanical condition, carbon-formation and exhaust smoke, system requirements, fuel oil ash deposition and corrosion, combustion-system design, performance requirements, types of primary zone, fuel injection, and combustion chamber types. The text then examines subsonic flow flameholder studies using a low pressure simulation technique; stabilization of hydrogen diffusion flames by flame-holders in supersonic flow at low stagnation temperatures; and augmentation systems for turbofan engines. The book takes a look at a consideration of the possible use of refractory ceramic materials for advanced combustion chamber design; cooling of flame tubes by steam injection; and combustion problems in the massive steam injection gas turbine. The selection is a valuable source of information for researchers interested in the process of combustion in advanced gas turbine systems.