Download or read book Active Control of Combustion Instabilities in Low Nox Gas Turbines written by Ben T. Zinn 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 Active Control of Combustion Instabilities in Gas Turbine Engines for Low Emissions Part I Physics Based and Experimentally Identified Models of Combustion Instability written by C. A. Jacobson and published by . This book was released on 2000 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper details the development of a thermoacoustic model and associated dynamic analysis. The model describes the results obtained in a gas fueled experimental combustion program carried out at UTRC. The contents of the paper are (a) the development of a thermoacoustic model composed of acoustic and heat release components, (b) the dynamic analysis of the resulting non-linear model using harmonic balance methods to compute linear stability boundaries and the amplitudes of oscillations and (c) the calibration of the model to experimental data.
Download or read book Active Control of Combustion Instabilities in Gas Turbine Engines for Low Emissions Part II Adaptive Control Algorithm Development Demonstration and Performance Limitations written by Andrzej Banaszuk and published by . This book was released on 2001 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present results of experiment with two distinct extremum-seeking adaptive algorithms for control of combustion instability suitable for reduction of acoustic pressure oscillations in gas turbine over large range of operating conditions. The algorithms consists of a frequency tracking Extended Kalman Filter to determine the in-phase component, the quadrature component, and the magnitude of the acoustic mode of interest, and a phase shifting controller with the controller phase tuned using an extremum-seeking algorithms. The algorithms are also applicable for control of oscillations of systems whose oscillation frequency and optimal control phase shift depends on operating conditions, and which are driven by strong broad-band disturbance. The algorithms have been tested in combustion experiments involving full-scale engine hardware and during simulated fast engine transients.
Download or read book Combustion Instabilities in Gas Turbine Engines written by Timothy C. Lieuwen and published by AIAA (American Institute of Aeronautics & Astronautics). This book was released on 2005 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Active control of combustion instability in a liquid fueled low NOx combustor ASME 98 GT 267 written by Jeffery M. Cohen and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented at the International Gas Turbine & Aeroengine Congress & Exhibition, Stockholm, Sweden, June 2 - June 5, 1998.
Download or read book Active Control of Combustion Instabilities in GE s Gas Turbines written by Benjamin Zinn and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Combination of Active Instability Control and Passive Measures to Prevent Combustion Instabilities in a 260MW Heavy Duty Gas Turbine written by J. Hermann and published by . This book was released on 2001 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reducing the output of NOx pollutants and enhancing efficiency are the two major aims pursued by developers of modern gas turbines. In order to achieve them. lean premix combustion is preferred turbine inlet temperatures and thus power densities within the combustion chamber system being continuously increased to augment efficiency. Due to this fact. the tendency of modern combustion systems to develop so-called self- excited combustion oscillations keeps increasing. After briefly discussing the oscillation problems encountered with the annular combustion chamber of a Siemens type V94.3A stationary gas turbine. particular attention will be paid to suppressing these oscillations by passive and active means. The passive measures presented. i.e. extending the burner nozzle were intended to detune the combustion system by prolonging the time lag required by the combustible mixture exiting the burner outlet to reach the combustion zone Moreover. to suppress periodic vortex shedding. another possible cause for combustion instabilities. those extensions were inclined in a certain angle with respect to the main flow direction. To prevent the in-phase lock of all 24 burners promoting the excitation of any azimuthal mode the burners were selected to have different time lags and were arranged asymmetrically within the annular combustion chamber. In addition to these passive measures, a multi-channel Active Instability Control (AIC) system was implemented to achieve further damping. With the AIC system presented. any homer oscillations occurring are measured by p-ressure sensors their signals are processed by means of a multi-channel controller and then transmitted to actuators designed to damp down combustion oscillations. The points of intervention selected to do so were the gas supplies of the pilot flames.
Download or read book Causes of Combustion Instabilities with Passive and Active Methods of Control for Practical Application to Gas Turbine Engines written by Michael D. Cornwell and published by . This book was released on 2011 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combustion at high pressure in applications such as rocket engines and gas turbine engines commonly experience destructive combustion instabilities. These instabilities results from interactions between combustion heat release, fluid mechanics and acoustics. This research explores the significant affect of unstable fluid mechanics processes in augmenting unstable periodic combustion heat release. The frequency of the unstable heat release may shift to match one of the combustors natural acoustic frequencies which then can result in significant energy exchange from chemical to acoustic energy resulting in thermoacoustic instability. The mechanisms of the fluid mechanics in coupling combustion to acoustics are very broad with many varying mechanisms explained in detail in the first chapter. Significant effort is made in understanding these mechanisms in this research in order to find commonalities, useful for mitigating multiple instability mechanisms. The complexity of combustion instabilities makes mitigation of combustion instabilities very difficult as few mitigation methods have historically proven to be very effective for broad ranges of combustion instabilities. This research identifies turbulence intensity near the forward stagnation point and movement of the forward stagnation point as a common link in what would otherwise appear to be very different instabilities. The most common method of stabilization of both premixed and diffusion flame combustion is through the introduction of swirl. Reverse flow along the centerline is introduced to transport heat and chemically active combustion products back upstream to sustain combustion. This research develops methods to suppress the movement of the forward stagnation point without suppressing the development of the vortex breakdown process which is critical to the transport of heat and reactive species necessary for flame stabilization. These methods are useful in suppressing the local turbulence at the forward stagnation point, limiting dissipation of heat and reactive species significantly improving stability. Combustion hardware is developed and tested to demonstrate the stability principles developed as part of this research. In order to more completely understand combustion instability a very unique method of combustion was researched where there are no discrete points of combustion initiation such as the forward stagnation point typical in many combustion systems including swirl and jet wake stabilized combustion. This class of combustion which has empirical evidence of great stability and efficient combustion with low CO, NOx and UHC emissions is described as high oxidization temperature distributed combustion. This mechanism of combustion is shown to be stable largely because there are no stagnations points susceptible to fluid mechanic perturbations. The final topic of research is active combustion control by fuel modulation. This may be the only practical method of controlling most instabilities with a single technique. As there are many papers reporting active combustion control algorithms this research focused on the complexities of the physics of fuel modulation at frequencies up to 1000 Hz with proportionally controlled flow amplitude. This research into the physics of high speed fluid movement, oscillation mechanical mechanisms and electromagnetics are demonstrated by development and testing of a High Speed Latching Oscillator Valve.
Download or read book Active Combustion Control for Aircraft Gas Turbine Engines written by and published by . This book was released on 2000 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Adaptive Control of Combution Instabilities Using Real time Modes Observation written by Clifford Edgar Johnson and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Combustion instabilities are a significant problem in combustion systems, particularly in Low NOx Gas Turbine combustors. These instabilities result in large-scale pressure oscillations in the combustor, leading to degraded combustor performance, shortened lifetime, and catastrophic combustor failure. The objective of this research was to develop a practical adaptive active control system that, coupled with an appropriate actuator, is capable of controlling the combustor pressure oscillations without a priori knowledge of the combustor design, operating conditions or instability characteristics. The adaptive controller utilizes an observer that determines the frequencies, phases and amplitudes of the dominant modes of the oscillations in real time. The research included development and testing of the adaptive controller on several combustors and on an unstable acoustic feedback system in order to analyze its performance. The research also included investigations of combustor controllability and combustor stability margin, which are critical issues for practical implementation of an active control system on an industrial combustor. The results of this research are directly applicable to a variety of combustors and can be implemented on full-scale industrial combustion systems.
Download or read book Active Control of Combustion and Its Applicatons written by A. J. Moran and published by . This book was released on 2001 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ducted flame in any of its forms can have the tendency to interact with its surroundings. When this interaction takes the form of thermo-acoustic instabilities the consequences can be grave. These instabilities have been recognised as a problem for many decades and have appeared in many forms of engine including rocket motors, ramjets, main engine gas turbine combustors and after burning system. It is true to say that the phenomena has not been truly understood and that many researchers have come up with several theories as to how these thermo-acoustic instabilities occur. In the field of engineering, the ability to fix the problem rather than fully understand the problem has been a principle that has been applied for many years. The approaches taken to fixing thermo-acoustic, problems have been either radical re-design of the combustion system or the application of passive damping techniques. In the past decade, however, a further technique has been given to the combustion designer, that technique being the ability to use active control. This paper outlines how the technique has been developed, from small scale pilot rig testing through to full engine demonstration, and how active control may be applied to land-based gas turbines in the future. With the introduction of ultra low emission lean pre-mixed combustion systems to land based gas turbines the propensity to exhibit thermo-acoustic instabilities has increased. Actively controlling the instability is a real option, the benefits of gaining extensive experience with the technology on land will help to promote the technology for future application to aircraft.
Download or read book Lean Combustion written by Derek Dunn-Rankin and published by Academic Press. This book was released on 2016-07-01 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lean Combustion: Technology and Control, Second Edition outlines and explains the latest advances in lean combustion technology and systems. Combustion under sufficiently fuel-lean conditions can have the desirable attributes of high efficiency and low emissions. The book offers readers both the fundamentals and latest developments in how lean burn (broadly defined) can increase fuel economy and decrease emissions, while still achieving desired power output and performance. This volume brings together research and design of lean combustion systems across the technology spectrum in order to explore the state-of-the-art in lean combustion. Readers will learn about advances in the understanding of ultra-lean fuel mixtures and how new types of burners and approaches to managing heat flow can reduce problems often found with lean combustion (such as slow, difficult ignition and frequent flame extinction). This book offers abundant references and examples of real-world applications. New to this edition are significantly revised chapters on IC engines and stability/oscillations, and new case studies and examples. Written by a team of experts, this contributed reference book aims to teach its reader to maximize efficiency and minimize both economic and environmental costs. Presents a comprehensive collection of lean burn technology across potential applications, allowing readers to compare and contrast similarities and differences Provides an extensive update on IC engines including compression ignition (diesel), spark ignition, and homogeneous charge compression ignition (HCCI) Includes an extensive revision to the Stability/Oscillations chapter Includes use of alternative fuels such as biogas and hydrogen for relevant technologies Covers new developments in lean combustion using high levels of pre-heat and heat recirculating burners, as well as the active control of lean combustion instabilities
Download or read book Reduced order Modeling and Active Control of Dry low emission Combustion written by Tongxun Yi and published by . This book was released on 2007 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Modeling of Combustion Instabilities and Their Active Control in a Gas Fueled Combustor written by Rajendran Mohanraj and published by . This book was released on 1998 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Emissions Combustion Dynamics and Control of a Multiple Swirl Combustor written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Application of Active Combustion Instability Control to a Heavy Duty Gas Turbine written by J. R. Seume and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented at the ASME ASIA '97 Congress & Exhibition, Singapore, Sep 30-Oct 2, 1997.
Download or read book Performance Enhancement of Gas Turbine Combustor by Active Control of Fuel Injection and Mixing Process Theory and Practice written by Christian O. Pascherelt and published by . This book was released on 2001 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unstable thermoacoustic modes were investigated and controlled in an experimental low-emission swirl stabilized combustor, in which the acoustic boundary conditions were modified to obtain combustion instability. Axisymmetric and helical unstable modes wore identified for fully premixed combustion These unstable modes were associated with flow instabilities related to the recirculation region on the combustor axis and shear layer in- stabilities at the sudden expansion (dump plane). The combustion structure associated with the different unstable modes was visualized by phase locked images of OH chemi- luminescence, The axisymmetric mode showed large variation of the heat release during one cycle, while the helical modes showed circumferential variations in the location of maximal heat release. Two feedback control methods employed to suppress thermoa- coustic pressure oscillations and to reduce emissions reviewed: proportional acoustic control and fuel modulations. Microphone sensors monitored the combustion process and provided input to the control systems. An acoustic actuation modulated the airflow and thus affected the mixing process and the combustion. Suppression levels of up to 25 dB in the pressure oscillations and a concomitant 10% reduction of NO(x) emissions were obtained. At the optimal control conditions It was shown that the major effect of the control system was to reduce the coherence of the vortical structures which gave rise to the thermoacoustic instability. The specific design of the investigated experimental burner allowed testing the effect of different modulated fuel injection concepts on the combustion instability modes. Symmetric and antisymmetric fuel injection schemes were tested. Suppression levels of up to 12 dB in the pressure oscillations were observed. In some cases concomitant reductions of NO and CO emissions were obtained.
