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 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 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 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 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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1993 with total page 1018 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermoacoustic Combustion Instability Control written by Dan Zhao and published by Academic Press. This book was released on 2023-02-13 with total page 1145 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
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 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 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 NASA SP written by and published by . This book was released on 1993 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Validation of an Adaptive Combustion Instability Control Method for Gas Turbine Engines written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-20 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes ongoing testing of an adaptive control method to suppress high frequency thermo-acoustic instabilities like those found in lean-burning, low emission combustors that are being developed for future aircraft gas turbine engines. The method called Adaptive Sliding Phasor Averaged Control, was previously tested in an experimental rig designed to simulate a combustor with an instability of about 530 Hz. Results published earlier, and briefly presented here, demonstrated that this method was effective in suppressing the instability. Because this test rig did not exhibit a well pronounced instability, a question remained regarding the effectiveness of the control methodology when applied to a more coherent instability. To answer this question, a modified combustor rig was assembled at the NASA Glenn Research Center in Cleveland, Ohio. The modified rig exhibited a more coherent, higher amplitude instability, but at a lower frequency of about 315 Hz. Test results show that this control method successfully reduced the instability pressure of the lower frequency test rig. In addition, due to a certain phenomena discovered and reported earlier, the so called Intra-Harmonic Coupling, a dramatic suppression of the instability was achieved by focusing control on the second harmonic of the instability. These results and their implications are discussed, as well as a hypothesis describing the mechanism of intra-harmonic coupling. Kopasakis, George and DeLaat, John C. and Chang, Clarence T. Glenn Research Center NASA/TM-2004-213198, AIAA Paper 2004-4028, E-14698
Download or read book Combustion Instabilities in Gas Turbine written by Giulietti Emanuele and published by LAP Lambert Academic Publishing. This book was released on 2015-08-04 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increasingly strict regulation for pollutant emissions has recently led engine manufacturers to develop combustors that meet various regulatory requirements. Lean-premixed combustion appears to be the most promising technology for practical systems at the present time. In lean-premixed combustion, the fuel and air are premixed upstream of the combustor to avoid the formation of stoichiometric regions. The combustor is operated with excess air to reduce the flame temperature; consequently, thermal NOx is virtually eliminated. Unsteady flow oscillations, also referred to as combustion instability, have emerged as a common problem, and hindered the development of lean-premixed combustors. These oscillations may reach sufficient amplitudes to interfere with engine operation, and in extreme cases, lead to failure of the system due to excessive structural vibration and heat transfer to the chamber. The book is organized in two parts: an extensive bibliographic review of combustion instabilities and the motivation of this work in part 1; and the study about a new diagnostic methodology for thermoacoustic instability detection and future control in part 2.
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 Characterization and Simulation of the Thermoacoustic Instability Behavior of an Advanced Low Emissions Combustor Prototype written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019-01-13 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Extensive research is being done toward the development of ultra-low-emissions combustors for aircraft gas turbine engines. However, these combustors have an increased susceptibility to thermoacoustic instabilities. This type of instability was recently observed in an advanced, low emissions combustor prototype installed in a NASA Glenn Research Center test stand. The instability produces pressure oscillations that grow with increasing fuel/air ratio, preventing full power operation. The instability behavior makes the combustor a potentially useful test bed for research into active control methods for combustion instability suppression. The instability behavior was characterized by operating the combustor at various pressures, temperatures, and fuel and air flows representative of operation within an aircraft gas turbine engine. Trends in instability behavior versus operating condition have been identified and documented, and possible explanations for the trends provided. A simulation developed at NASA Glenn captures the observed instability behavior. The physics-based simulation includes the relevant physical features of the combustor and test rig, employs a Sectored 1-D approach, includes simplified reaction equations, and provides time-accurate results. A computationally efficient method is used for area transitions, which decreases run times and allows the simulation to be used for parametric studies, including control method investigations. Simulation results show that the simulation exhibits a self-starting, self-sustained combustion instability and also replicates the experimentally observed instability trends versus operating condition. Future plans are to use the simulation to investigate active control strategies to suppress combustion instabilities and then to experimentally demonstrate active instability suppression with the low emissions combustor prototype, enabling full power, stable operation. DeLaat, John C. and Paxson, Daniel E. Glenn Research Cent
Download or read book ASME Technical Papers written by and published by . This book was released on 2000 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Adaptive Instability Suppression Controls Method for Aircraft Gas Turbine Engine Combustors written by George Kopasakis and published by BiblioGov. This book was released on 2013-07 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: An adaptive controls method for instability suppression in gas turbine engine combustors has been developed and successfully tested with a realistic aircraft engine combustor rig. This testing was part of a program that demonstrated, for the first time, successful active combustor instability control in an aircraft gas turbine engine-like environment. The controls method is called Adaptive Sliding Phasor Averaged Control. Testing of the control method has been conducted in an experimental rig with different configurations designed to simulate combustors with instabilities of about 530 and 315 Hz. Results demonstrate the effectiveness of this method in suppressing combustor instabilities. In addition, a dramatic improvement in suppression of the instability was achieved by focusing control on the second harmonic of the instability. This is believed to be due to a phenomena discovered and reported earlier, the so called Intra-Harmonic Coupling. These results may have implications for future research in combustor instability control.
