Dissertations / Theses: 'Control of the combustion'

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Strand, Carina Renée. "Catalytic combustion control." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-21120.

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A mathematical model representing the dynamic behaviour observed at the actual catalytic incineration plant at Perstorp was derived. The model equations for the two main process units, the heat exchanger and the incinerator, were based on the lumped systems approach in order to avoid using partial differential equations. The model was written in Matlab and implemented in Simulink using s-functions for the dynamic study. By analyzing the dynamic data from the actual plant, it was discovered that the possible source of the ocassional large temperature variations in the incinerator is the periodic variations in the inlet compositions, amplified the overly agressive air valve controller combined with a significant dead time. This results in oscillations due to overshooting. This behaviour was successfully reproduced using the derived model. Two possibilities for improving the control performance were investigated, both using already existing sensors and actuators. The first control improvement involved reducing the proportional gain according to the SIMC tuning rules for PI controllers. This resulted in a significant reduction in the amplitude of the oscillations in the temperatures throughout the reactor, and thus a more stable performance. Finally, cascade control was implemented using the faster-responding catalyst bed temperature for the inner loop, and the reactor outlet temperature for the outer loop. This provided the most optimal results with the best disturbance rejection as it is able to compensate for the disturbance before it is detected in the outlet temperature.

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Bhidayasiri, Roongrueng. "Control of combustion." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286243.

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LI, GUOQIANG. "EMISSIONS, COMBUSTION DYNAMICS, AND CONTROL OF A MULTIPLE SWIRL COMBUSTOR." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1092767684.

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Fussey, Peter Michael. "Automotive combustion modelling and control." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:ec66cbb1-407e-431c-bd77-e67bcf33be3a.

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This thesis seeks to bring together advances in control theory, modelling and controller hardware and apply them to automotive powertrains. Automotive powertrain control is dominated by PID controllers, look-up tables and their derivatives. These controllers have been constantly refined over the last two decades and now perform acceptably well. However, they are now becoming excessively complicated and time consuming to calibrate. At the same time the industry faces ever increasing pressure to improve fuel consumption, reduce emissions and provide driver responsiveness. The challenge is to apply more sophisticated control approaches which address these issues and at the same time are intuitive and straightforward to tune for good performance by calibration engineers. This research is based on a combustion model which, whilst simplified, facilitates an accurate estimate of the harmful NO_x and soot emissions. The combustion model combines a representation of the fuel spray and mixing with charge air to give a time varying distribution of in-cylinder air and fuel mixture which is used to calculate flame temperatures and the subsequent emissions. A combustion controller was developed, initially in simulation, using the combustion model to minimise emissions during transient manoeuvres. The control approach was implemented on an FPGA exploiting parallel computations that allow the algorithm to run in real-time. The FPGA was integrated into a test vehicle and tested over a number of standard test cycles demonstrating that the combustion controller can be used to reduce NO_x emissions by over 10% during the US06 test cycle. A further use of the combustion model was in the optimisation of fuel injection parameters to minimise fuel consumption, whilst delivering the required torque and respecting constraints on cylinder pressure (to preserve engine integrity) and rate of increase in cylinder pressure (to reduce noise).

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Evesque, Stéphanie Marie-Noelle. "Adaptive control of combustion oscillations." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620985.

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Horning, Marcus. "Feedback Control for Maximizing Combustion Efficiency of a Combustion Burner System." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1459356183.

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7

Lundström, Mikael. "Model Based HCCI Engine Combustion Control." Thesis, KTH, Reglerteknik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-107513.

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An Homogenous Charge Compression Ignition engine is a hybrid between a Diesel and an Otto Engine. It has good fuel efficiency, close to a Diesel engine and also very low emissions of NOX and nearly no particulate soot. Other emissions are higher but can be after treated by a catalyst. The engine has not yet been fully developed so far and lacks among others a good automatic control of the combustion angle which should be held in a small window to achieve the best performance. The objective in this thesis is to achieve fast control that can hold the combustion angle window for changes in inlet pressure, loads and engine speeds. The challenges are that the system has a delay which limits the bandwidth, the dynamics change with different working conditions and a relatively large noise amplitude. Using combustion angle as reference, valve timings as control signal and other variables as engine speed, inlet pressure and load changes as disturbances, a closed loop control system can be defined. Two control methods using different kinds of variable valve timings and three controllers for each method were designed to cover most of the working conditions. These were connected by a hybrid automaton which handles all transitions and choice of controller. The result was a fast control with a 6-8 engine cycles risetime for reference changes and it can suppress inlet pressure and load disturbances well inside the combustion window. The noise showed to be white, that is using all frequencies. To achieve both a fast control and not magnify the noise a non-linear compensation link was designed that uses less gain and bandwidth for small errors. A problem with this kind of dynamic solution is engine speed ramps which needs fast reaction times which was impossible due to the delay. A proposed solution is to use mappings from non-delayed variables to do necessary adjustments of the control signal fast enough.

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Tsai, Rong-Feng. "Sources and control of combustion oscillation." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265120.

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Hathout, Jean-Pierre 1969. "Modeling and control of combustion instability." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/88841.

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Zhao, Dan. "Tuned passive control of combustion instabilities." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611839.

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11

Mohanraj, Rajendran. "Modeling of combustion instabilities and their active control in a gas fueled combustor." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/12089.

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Keshav, Saurabh. "Using Plasmas for High-Speed Flow Control and Combustion Control." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1222026159.

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Lee, Jae-Yeon. "Fast and slow active control of combustion instabilities in liquid-fueled combustors." Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04072004-180036/unrestricted/lee%5fjae-yeon%5f200312%5fphd.pdf.

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Coker, Adam. "Investigations of active, combustion instability control effectiveness." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/12516.

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Felsch, Christian. "Combustion modeling for diesel engine control design." Aachen Shaker, 2009. http://d-nb.info/997696826/04.

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Seywert, Claude Culick F. Culick F. "Combustion instabilities : issues in modeling and control /." Diss., Pasadena, Calif. : California Institute of Technology, 2001. http://resolver.caltech.edu/CaltechETD:etd-01252007-135242.

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17

Park, Sungbae 1973. "Active combustion control : modeling, design and implementation." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/27107.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.
Includes bibliographical references (leaves 111-116).
Continuous combustion systems common in propulsion and power generation applications are susceptible to thermoacoustic instability, which occurs under lean burn conditions close to the flammability where most emissions and efficiency benefits are achieved, and near stoichiometry where often high power density can be realized. This instability is undesirable because the accompanying large pressure and heat release rate oscillations lead to high levels of acoustic noise and vibration as well as structural damage. Active control is one approach using which such instabilities can be mitigated. Over the past five to ten years, it has been shown conclusively through several lab-scale studies that active control is highly successful in suppressing the pressure oscillations. This success has set the stage for transition of the technology from laboratories to large-scale applications in propulsion and power generation. This thesis provides some of the building blocks for enabling this transition. The first building block concerns the modeling of hydrodynamics and its interactions with the other components that contribute to combustion dynamics. The second is the impact of active control on emissions even while suppressing the pressure instability. The third is the evaluation of model-based active controllers in realistic combustors with configurations that include swirl, large convective delays and unknown changes in the operating conditions. The above three building blocks are investigated in the thesis experimentally in three different configurations. The first is a 2D backward facing step combustor, constructed at MIT, with the goal of investigating the flame-vortex interactions and the impact of active control on emissions. The second
(cont.) is a dump combustor, constructed at University of Maryland, so as to reproduce more realistic ramjet conditions. The third is an industrial swirl-stabilized combustor, constructed at University of Cambridge, to mimic realistic industrial gas combustor configurations which typically include large convective time delays, swirl, and on-line changes in the operating conditions. Results obtained from these three configurations show that through an understanding of the underlying physics and reduced-order modeling, one can design an appropriate actuation, sensing and control algorithm, all of which lead to model-based active control that reduces pressure oscillations to background noise.
by Sungbae Park.
Ph.D.

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18

Wattrus, Mark. "Optimised combustion control for different diesel fuels." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/5455.

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Wang, Chuan-Han. "Actively-tuned passive control of combustion instabilities." Thesis, University of Cambridge, 2004. https://www.repository.cam.ac.uk/handle/1810/251917.

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20

Lundin, Eva. "Adaptive air-fuel ratio control for combustion engines." Thesis, Linköping University, Department of Electrical Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-56651.

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Around the world, vehicle emission regulations become stricter, increasing exhaust emission demands. To manage these rules and regulations, vehicle manufacturers put a lot of effort into minimizing the exhaust emissions. The three-way catalytic converter was developed, and today it is the most commonly used device to control the exhaust emissions.

To work properly the catalytic converter needs to control the air-fuel mixture with great precision. This then increases the demands on the engine management systems, causing them to become more complex. With increased complexity, the time effort of optimizing parameters has grown drastically, hence increasing development costs. In addition to this, operating conditions change due to vehicles age, requiring further optimization of the parameters while running.

To minimize development cost and to control the air-fuel mixture with great precision during an engines full life span, this master thesis proposes a self-optimized system, i.e. an adaptive system, to control the air-fuel mixture.

In the suggested method, the fuel injection to the engine is controlled with help of a linear lambda sensor, which measures the air-fuel mixture. The mapping from injection to measured air-fuel mixture forms a nonlinear system. It can be approximated as a linear function at static engine operating points, allowing the system at each static point to be modelled as a first order system with long time delay. To enable utilization over full operating area, and not only in static point, the controller uses large maps, so called gain-scheduling maps, to change control parameters.

The tested controller is model based. It uses an Otto-Smith Predictor and a feed forward connection of target air-fuel. The model parameters in the controller are updated while driving and the adaptation method used is based on a least squares algorithm.

The performance of the adapted controller and the adaptation method is tested in both simulation environment and in vehicle, showing good potential.

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21

Young, Tobias J. "The dynamics and control of in-situ combustion." Thesis, University of Bath, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242525.

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Improved oil recovery (lOR) techniques target the 60% of oil left behind by primary and secondary methods (those that utilise the natural energy of an oil reservoir). Air injection in situ combustion (lSC) is a thermal lOR technique used in general to increase the temperature in a reservoir and in turn reduce the viscosity of the oil. This increases the mobility of the oil and can lead to significant improvement in recovery factors. The process is complex and much work is needed to improve modeling capabilities essential for reservoir management. To investigate high pressure air injection a combustion tube facility has been commissioned and four in situ combustion tube tests completed. This involved the development of data acquisition and control software (lsc View) to fully automate the air injection facility. The ISC tests were carried out with a West Shetland Clair crude oil of 19.7°API and air injection fluxes between 12 and 70m3/m2hr and pressures between 50 and 100 bar. Post-mortem analysis of the burned cores showed 100% oil displacement in areas of core swept by the combustion front. In these areas the amount fuel burned varied between 4.6 and 15.3 %OOIP (original oil in place). The combustion front temperatures varied between 450°C and 730°C. It was found that combustion front temperature increased with air injection flux. The combustion front velocity varied between 10.4 and 22.2cmlhr. The combustion front velocity was observed to increase with pressure thus the combustion front velocity and hence propagation of the combustion front was shown to be reaction rate dependent. History matching of the ISC tests was completed using the STARS simulator (Computer Modeling Group) a fully implicit non isothermal reservoir simulator. The simulations showed that when the grid size approached that of the actual reaction zone then the kinetics at different pressures did not change. Therefore, at this grid scale, the kinetic parameters used for a pseudo component representation of the oil can be applied as if it were a pure component, independent of pressure.

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Chandrabalan, Senbaha Karthikeyan. "Development of a parameter for combustion noise control." Thesis, KTH, Maskinkonstruktion (Inst.), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-143659.

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De ständigt ökande kraven från emissionslagstiftningen har gjort att fordonsindustrins huvudfokus har riktats mot att minska utsläppen från koldioxid (CO2) och bildandet av andra föroreningar från nya motorer. Ett resultat av detta är att flera motortillverkare har valt nya teknikspår som ofta leder till ökat motorbuller vilket är ofördelaktigt tillsammans med dieselmotorns karaktäristiska redan höga förbränningsljud. Exempelvis leder ”downsizing” till att motorns belastning ökar vilket i sin tur ger ökat motorbuller. I detta examensarbete har en undersökning för att identifiera lämpliga parametrar som kan förutsäga förbränningsljud utförts. Utredningen har fokuserat på olika parametrars noggrannhet associerade med förbränningsljud vid olika motorkörfall. Lämpliga parametrar inkluderades i ett Rapid Control Prototyping (RCP) system och verifierades genom att använda mikrofoninspelning på en akustisk chassidynamometer. Utredningen visar att maximal grad av värmefrigivning över tid överensstämmer bra med förbränningsljud vid olika körfall. Detta kunde också påvisas med resultaten av ljudupptagningarna från den akustiska chassidynamometern.
Ever increasing demand from the legislative requirements has shifted the focus of Automotive Engineering Industries on reducing the overall carbon dioxide (CO2) from the vehicle and reducing the pollutant formation at source. This result in many engine manufacturers opting for new technologies, often these technologies results in an adverse effect on noise adding to the inherent characteristic noise of diesel engines. For example, downsizing the engine results in increase of mean operating load resulting in increased noise. In this thesis work, an investigation for identifying a suitable parameter for predicting combustion noise is performed. The work investigates different parameters associated with combustion noise for its accuracy at various engine operating conditions. Then suitable parameters are implemented on a Rapid Control Prototyping (RCP) system and verified using microphone recording on an acoustic chassis dynamometer. The outcome of the study suggest that maximum rate of heat release with respect to time correlates well to the combustion noise at different operating conditions, it is also verified using the microphone data measured on acoustic chassis dynamometer.

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Brandstetter, Markus. "Robust air-fuel ratio control for combustion engines." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627144.

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Winberg, Mathias. "Noise and Vibration Control of Combustion Engine Vehicles." Doctoral thesis, Karlskrona : Blekinge Institute of Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00281.

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Noise and vibrations have over the last two decades been regarded as significant environmental health problems. Regulations regarding acoustic as well as vibration levels have therefore become more stringent. This thesis embraces two different techniques to reduce unwanted noise and vibrations, spectral subtraction and active noise and vibration control. The applications treated for noise and vibration problems are mainly means of transportation driven by combustion engines as for example, helicopters, boats, and cars. All these vehicles have low-frequency noise and vibration problems which are difficult to solve by means of passive isolation, hence alternative methods must be sought. Two different scenarios are studied. First, the high noise level in the interior of the vehicle is accepted and the humans inside are equipped with headsets utilizing both passive as well as active noise control. If the means of transportation employs some kind of communication equipment, such as for a cellular telephone or an intercom radio, the noisy speech signal picked up by the microphone is cleansed by spectral subtraction, which is a non-linear filtering method employed in the frequency domain. In the second scenario the entire interior of the vehicle is subjected to noise and vibration reduction by means of active noise and vibration control. Active noise and vibration control is the art of reducing a primary sound or vibration field by interference with a secondary anti-field. The thesis focus on real-life applications which implies that a lot of measurements and practical difficulties must be treated for both scenarios, especially in the area of active noise and vibration control. In this area, the basic idea seems straight-forward, but implementing it in large and complex structures, such as vehicles, is extremely difficult, in particular if high attenuation is required.

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Gray, D. T. "The control of fluidised combustors." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373677.

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Illingworth, Simon James. "Feedback control of oscillations in combustion and cavity flows." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/224778.

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This thesis considers the control of combustion oscillations, motivated by the susceptibility of lean premixed combustion to such oscillations, and the long and expensive development and commissioning times that this is giving rise to. The controller used is both closed-loop, employing an actuator to modify some system parameter in response to a measured signal, and adaptive, meaning that it is able to maintain control over a wide range of operating conditions. The controller is applied to combustion systems with annular geometries, where instabilities can occur both longitudinally and azimuthally, and which require multiple sensors and multiple actuators for control. One of the requirements of Lyapunov-based adaptive control which is particularly troublesome for combustion systems is then addressed: that the sign of the high-frequency gain of the open-loop system is known. We address it by using an adaptive controller which employs a Nussbaum gain, and successfully apply it experimentally to combustion oscillations in a Rijke tube. Another type of fluid-acoustic resonance is then considered: the compressible flow past a shallow cavity. We start by finding a linear model of the cavity flow's dynamics, or its 'transfer function', which we identify from direct numerical simulations. We compare this measured transfer function to that given by a conceptual model which is based on the Rossiter mechanism, and which models each component of the flow physics separately. We then look at using closed-loop control to eliminate these cavity oscillations. We start by designing a robust H₂ controller based on a balanced reduced order model of the system, the model being provided by the Eigensystem Realization Algorithm (ERA). The robust controller provides closed-loop stability over a much wider Mach number range than seen in previous studies. Finally, we look at the suitability of the adaptive controller, earlier developed for combustion oscillations, for the cavity. Based on some general properties of the cavity flow, and by using collocated control, the oscillations are eliminated at all Mach numbers tested in the range 0.4 ≤ M ≤ 0.8.

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Felsch, Christian [Verfasser]. "Combustion modeling for diesel engine control design / Christian Felsch." Aachen : Shaker, 2009. http://d-nb.info/999433881/34.

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Jafari, Ahmad. "Analysis and control of harmful emissions from combustion processes." Thesis, Brunel University, 2000. http://bura.brunel.ac.uk/handle/2438/6620.

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The harmful effects of air pollutants on human beings and environment have been the major reason for efforts in sampling, analysis and control of their sources. The major pollutants emitted to atmosphere from stationary combustion processes are nitrogen oxides, inorganic acids, carbon dioxide, carbon monoxide, hydrocarbon and soot. In the current work two methods are developed for sampling and analysis of volatile chlorinated aromatic hydrocarbons and semi-volatile chlorinated aromatic hydrocarbons for example 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) by using solid sorbent, thermal desorption and high resolution GC-MS. The capacity of several solid sorbents is compared by breakthrough value and percentage recovery ofthe analyte from the sorbent. The thermal stability of polyvinyl chloride (PVC) and PVC in the presence of metals is studied because PVC is a polymer commonly found in solid waste derived from medical waste, car recycling and electrical cable. Harmful pollutant emissions from combustion and pyrolysis of PVC are measured using the novel method developed in this work. The main inorganic volatile is HCl while benzene is the major volatile organic formed under pyrolysis and combustion conditions. The thermal degradation of PVC produces a large number of chlorinated aromatic hydrocarbon, aromatic hydrocarbon and short chain linear gases. A study is designed for control of harmful pollutants from combustion of PVC including HCl, aromatic hydrocarbon, chlorinated aromatic hydrocarbons and soot. It is reported that the presence of metal oxides have the ability to control the level of harmful emissions by facilitating the producing of more short chain linear gases. A study is designed for control of harmful pollutants from combustion of PVC including HCl, aromatic hydrocarbon, chlorinated aromatic hydrocarbons and soot. It is reported that the presence of metal oxides have the ability to control the level of harmful emissions by facilitating the producing of more short chain linear gases. Two methods are developed for the control of soot from liquid and gas combustion process by using applied fields, Magnetic and electric fields. In this study, it is shown that an increase in applied field strength leads to an increase in flame temperature but a decrease in the length of flame. The level of soot emission was decreased in presence of an applied field. A discussion of the effect of applied fields on the combustion process is given.

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Mamani, A., G. Quispe, and C. Raymundo-Ibañeez. "Electromechanical Device for Temperature Control of Internal Combustion Engines." IOP Publishing Ltd, 2019. http://hdl.handle.net/10757/656303.

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Internal combustion engines are the most commonly used engines in the automotive world. However, these engines lack an overheating prevention system against cooling system failures when they exceed their normal operating temperature. Less experienced drivers (users) usually do not notice overheating until the engine stops, generating economic expenses in engine repairs. As such, this paper describes the design and construction of an electromechanical device to prevent engine overheating. This device is installed in a vehicle and operates independently from the electronic control unit (ECU); it records the coolant temperature and controls air admission to the engine of the vehicle in which it is installed. In addition, a new Arduino-based card will receive signals from a temperature sensor as input and process them according to its programming. Then, it will send signal outputs to the actuators: A servomotor, monitor, LED display, and buzzer. To control the intake flow, a butterfly valve is used with the servomotor. This valve partially or totally restricts the engine airflow, based on the temperature programmed for the Arduino, thus protecting the engine from overheating.

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Prashanth, Prakash. "Post-combustion emissions control for aero-gas turbine engines." Thesis, Massachusetts Institute of Technology, 2018. https://hdl.handle.net/1721.1/122402.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2018
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 47-50).
Aviation NO[subscript x] emissions have an impact on air quality and climate change, where the latter is magnified due to the higher sensitivity of the upper troposphere and lower stratosphere. In the aviation industry, efforts to increase the efficiency of propulsion systems are giving rise to higher overall pressure ratios which results in higher NO[subscript x] emissions due to increased combustion temperatures. This thesis identifies that the trend towards smaller engine cores (gas generators) that are power dense and contribute little to the thrust output presents new opportunities for emissions control that were previously unthinkable when the core exhaust stream contributed significant thrust. This thesis proposes and assesses selective catalytic reduction (SCR), which is a post-combustion emissions control method used in ground-based sources such as power generation and heavy-duty diesel engines, for use in aero-gas turbines.
The SCR system increases aircraft weight and introduces a pressure drop in the core stream. The effects of these are evaluated using representative engine cycle models provided by a major aero-gas turbine manufacturer. This thesis finds that employing an ammonia-based SCR can achieve close to 95% reduction in NO[subscript x] emissions for ~0.4% increase in block fuel burn. The large size of the catalyst needs to be housed in the body of the aircraft and hence would be suitable for future designs where the engine core is also within the fuselage, such as would be possible with turbo-electric or hybrid-electric designs. The performance of the post-combustion emissions control is shown to improve for smaller core engines in new aircraft in the NASA N+3 time-line (2030-2035), suggesting the potential to further decrease the cost of the ~95% NO[subscript x] reduction to below ~0.4% fuel burn.
Using a global chemistry and transport model (GEOS-Chem) this thesis estimates that using ultra-low sulfur (<15 ppm fuel sulfur content) in tandem with post-combustion emissions control results in a ~92% reduction in annual average population exposure to PM₂.₅ and a ~95% reduction in population exposure to ozone. This averts approximately 93% of the air pollution impact of aviation.
by Prakash Prashanth.
S.M.
S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics

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Yi, Tongxun. "Reduced-Order Modeling and Active Control of Dry-Low-Emission Combustion." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1172865804.

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32

Ma, Jia. "Model-based control of electro-pneumatic intake and exhaust valve actuators for IC engines." Diss., Connect to online resource - MSU authorized users, 2008.

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Thesis (Ph. D.)--Michigan State University. Dept. of Mechanical Engineering, 2008.
Title from PDF t.p. (viewed on Mar. 31, 2009) Includes bibliographical references (p. 150-151). Also issued in print.

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33

Johnson, Clifford Edgar. "Adaptive control of combution instabilities using real-time modes observation." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-03232006-223052/.

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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2006.
Zinn, Ben, Committee Chair ; Glezer, Ari, Committee Member ; Shelton, Samuel, Committee Member ; Lieuwen, Tim, Committee Member ; Neumeier, Yedidia, Committee Member.

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34

Isella, Giorgio C. Culick F. "Modeling and simulation of combustion chamber and propellant dynamics and issues in active control of combustion instabilities /." Diss., Pasadena, Calif. : California Institute of Technology, 2001. http://resolver.caltech.edu/CaltechETD:etd-03012006-093758.

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35

Leroy, Thomas. "Cylinder filing control of variable-valve-actuation equipped internal combustion engines." Paris, ENMP, 2010. https://theses.hal.science/tel-00506471.

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Nous étudions la production de couple et de polluants de moteurs à combustion interne à distribution variable d'un type fréquemment répandu dans l'industrie automobile (moteurs Diesel ou essence). Les systèmes de distribution variable (VVA pour Variable Valve Actuation) ont été introduits dans les moteurs pour optimiser l'efficacité du fonctionnement global sur des plages très larges de points de fonctionnement, considérés à l'équilibre. A tout instant, les résultats de la combustion dépendent du remplissage en air/gaz brûlés du cylindre, qui lui même dépend de la position des actionneurs VVA et des conditions dans le collecteur d'admission. Ces deux sous-systèmes ont des temps de réponse différents, ce qui conduit, pendant les transitoires, à des pertes d'efficacit ́e du moteur. Dans cette thèse, nous proposons une solution a ce problème, qui prend la forme de boucle de coordination entre les sous-systèmes de contrôle de bas-niveau. Cette coordination s'effectue par l'intermédiaire d'un modèle de remplissage développé dans ce manuscrit. Des résultats expérimentaux établissent qu'il est possible d'améliorer la production de couple et de réduire les polluants
The production of torque and pollutants of Variable Valve Actuation equipped internal combustion engines found in the automotive industry (both Diesel and gasoline engines) is studied. Variable Valve Actuation (VVA) is a technology which has been introduced to optimize engine efficiency at steady-states covering a wide range of operating conditions. In more details, the outcome of the internal combustion engine (torque and pollutant) depends on the cylinder filling at each stroke which, itself, depends on the VVA positions and the engine intake manifold conditions. These two subsystems have inconsistent response times which results in efficiency losses during transient operations. In this manuscript, a remedy for this issue which takes the form of coordination loops of low-level controllers is proposed. This coordination uses a cylinder filling model, designed in the thesis. Experimental results prove that torque production and pollutant emissions can be improved

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36

Uhm, Jong Ho. "Nature and control of combustion oscillations in sudden expansion flows." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271641.

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Arning, Johannes. "Experimental studies of combustion control in a gasoline HCCI engine." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609247.

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Cornwell, Michael. "Causes of Combustion Instabilities with Passive and Active Methods of Control for practical application to Gas Turbine Engines." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307323433.

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Yan, Fengjun. "Diesel Engine Advanced Multi-Mode Combustion Control and Generalized Nonlinear Transient Trajectory Shaping Control Methods." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1337887426.

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40

Crawford, Jackie H. III. "Factors that limit control effectiveness in self-excited noise driven combustors." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43647.

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A full Strouhal number thermo-acoustic model is purposed for the feedback control of self excited noise driven combustors. The inclusion of time delays in the volumetric heat release perturbation models create unique behavioral characteristics which are not properly reproduced within current low Strouhal number thermo acoustic models. New analysis tools using probability density functions are introduced which enable exact expressions for the statistics of a time delayed system. Additionally, preexisting tools from applied mathematics and control theory for spectral analysis of time delay systems are introduced to the combustion community. These new analysis tools can be used to extend sensitivity function analysis used in control theory to explain limits to control effectiveness in self-excited combustors. The control effectiveness of self-excited combustors with actuator constraints are found to be most sensitive to the location of non-minimum phase zeros. Modeling the non-minimum phase zeros correctly require accurate volumetric heat release perturbation models. Designs that removes non-minimum phase zeros are more likely to have poles in the right hand complex plane. As a result, unstable combustors are inherently more responsive to feedback control.

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41

Tran, Nicolas. "Influence de la condition limite acoustique amont sur les instabilités de combustion de grande amplitude : conception d’un système robuste de contrôle d’impédance." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2009. http://www.theses.fr/2009ECAP0013/document.

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Les contraintes économiques, environnementales et sociétales de ces vingt dernières années notamment dans les domaines de l’énergie et des transports ont débouché sur le développement de nouvelles technologies faisant intervenir la combustion pauvre et prémélangée. Ce mode de combustion à partir d'un mélange homogène conduit à des températures de flamme plus faibles qui permettent de réduire les émissions d'oxydes d'azote tout en limitant la production d'oxydes de carbone. Pour autant, la combustion pauvre prémélangée présente le désavantage d’être sensible à toute forme de couplage notamment acoustique, menant à des instabilités de combustion. Ces instabilités sont largement étudiées, mais restent très difficiles à prévoir car elles font intervenir de nombreux phénomènes physiques multi-échelles. Dans la plupart des cas les oscillations résultent d’un couplage résonant entre la dynamique de la combustion et l’acoustique du système. Les conditions aux limites acoustiques du système déterminent la structure du champ de pression dans l’installation, ainsi que les flux acoustiques entrants et sortants. Malgré son importance, l’influence des conditions aux limites n’est pas toujours bien comprise et prise en compte et elle ne fait pas l’objet d’études systématiques. Les conditions aux limites acoustiques ne sont pas faciles à déterminer expérimentalement sur des configurations pratiques et leur contrôle est rarement envisagé. L’objectif de ce travail est donc de répondre à ce manque d’information, en étudiant sur un banc de combustion turbulente (CTRL-Z) l’influence de la condition acoustique d’entrée sur les oscillations de combustion auto-entretenues qui apparaissent dans la chambre de combustion. Un système de contrôle a été développé pour piloter l’impédance du système de prémélange de façon passive, sans modification des conditions de fonctionnement ou de la géométrie du brûleur. Ce système de contrôle d’impédance (ICS, « Impedance Control System ») s’appuie sur une utilisation de plaques perforées faiblement poreuses, au travers desquelles circule un écoulement. Un piston mobile permet de piloter la profondeur de la cavité résonante formée en amont des plaques, et ainsi de piloter leurs impédances. L’impédance de ces plaques perforées a été étudiée pour de faibles et de forts niveaux d’excitation acoustique, et un critère de transition entre les régimes linéaire et non-linéaire a été déterminé. L’ICS a été optimisé pour permettre un contrôle du module du coefficient de réflexion de 0 à 1 sur une large plage de fréquences (100 à 1000 Hz) et de niveaux d’amplitude de perturbations (100 à 150 dB) couvrant ainsi la gamme des instabilités thermoacoustiques classiques. L’ICS est utilisé pour contrôler l’impédance d’entrée du système de prémélange du banc CTRL-Z, en regard de la zone de combustion. L’analyse spectrale des fluctuations de pression et de dégagement de chaleur en fonction de l’impédance d’entrée démontre qu’il est possible d’obtenir un amortissement de l’instabilité principale pouvant atteindre 20 dB. Ces résultats sont confirmés par une estimation au premier ordre d’un bilan d’énergie acoustique prenant en compte le terme source dû à la combustion ainsi que les flux acoustiques en amont et aval de la zone de flamme. Ce bilan démontre par ailleurs l’importance du flux d’énergie transmis vers l’amont, du même ordre de grandeur que le terme source, et souligne la nécessité de prendre en compte ces flux pour déterminer correctement le taux de croissance de l’énergie. Finalement, une analyse acoustique de l'installation a été menée pour déterminer la nature des modes d'instabilités observés et pour examiner les conditions nécessaires au bon fonctionnement de l'ICS
Combustion instabilities induced by a resonant flame-acoustic coupling are commonly observed in most applications of combustion from gas turbines to domestic or industrial boilers. These oscillations are detrimental by nature, and are still very difficult to predict at the design stage of a combustor. They imply numerous physical phenomena at multiple scales. They mainly result from a resonant coupling between the unsteady combustion and the acoustics of the system. The basic driving and coupling mechanisms have been extensively studied: acoustics in complex geometries and combustion dynamics of turbulent swirled flames are now reasonably well understood. However the effects of the acoustic boundary conditions on the system stability are less well documented, as they are not easy to access or to control in practical systems. They are however of prime importance as they determine the acoustic fluxes at the inlets and outlets of the combustor, as well as the preferential eigenfrequencies of the system. The main objective of this study is to investigate experimentally the influence of the inlet boundary condition of a generic turbulent burner on the observed self-sustained thermoacoustic oscillations. To carry out this investigation, a passive control solution has been developed. An innovative use of perforated panels with bias flow backed by tunable cavities allows to control the acoustic impedance at the inlet of a lean swirled-stabilized staged combustor (CTRL-Z facility). This impedance control system (ICS) has been initially designed and tested in a high load impedance tube. This facility also allowed to develop a robust impedance measurement technique, along with experimental protocols to measure acoustic velocities and fluxes. The acoustic response of perforates in both linear and nonlinear regimes was investigated as function of the plate porosity, bias flow velocity, back-cavity depth and incident pressure wave amplitude and frequency. The transition between the linear regime and the detrimental nonlinear regime has been linked to the perforates geometrical and operational parameters. As a result the ICS enables control of its acoustic reflection coefficient from 1 to 0 in a wide frequency range, 100 to 1000 Hz, for low and large incident pressure amplitudes (from 100 to 150 dB). The ICS, once implemented on the CTRL-Z facility, allowed to passively control the inlet boundary condition of the combustion rig. The impedance measurement technique was successfully used in harsh combustion situations, with high noise levels, to obtain in-situ measurements of the ICS impedance. Spectral analysis of the pressure and heat-release rate fluctuations demonstrated damping of the main self-sustained oscillation by up to 20 dB. A quantitative estimation of the acoustic energy balance was then obtained, highlighting the importance of the inlet acoustic flux. In this configuration, this term is of the same order of magnitude as the driving Rayleigh source term. Finally, an acoustic analysis of the combustion rig was led to determine the nature of the observed combustion instabilities modes and examine conditions required for an effective use of the ICS

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Richards, John S. "An Exploration of Secondary Fuel Injection as Actuation for Control of Combustion Instabilities in a Laminar Premixed Tube Combustor." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/32096.

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Active control of combustion instabilities through secondary fuel injection is a control method that has gained a lot of attention in the past decade. Previous control schemes with acoustic loudspeakers are not practical in full-scale gas turbines due to the extreme temperatures and acoustic power requirements. Much work has gone into controlling these thermoacoustic instabilities with secondary fuel control. Control of a laminar premixed tube combustor through secondary fuel actuation is the concentration of this work. It is the first known published attempt to control a laminar premixed tube combustor through secondary fuel actuation. Due to the low flow rates within the tube combustor an innovative injection technique had to be constructed to perform the secondary fuel actuation. The gaseous fuel is injected only one millimeter above the location of the flame through one, two, or four injectors. These injectors were designed to overcome the serious problem of pulse diffusion. This technique enabled the tube combustor to be controlled through secondary fuel injection. Accompanying the innovative fuel injection technique is a duty cycle modulation technique that was a prime contributor to the success of the control system. This method enabled the system to be controlled at conditions that were uncontrollable with a fixed duty cycle. The overall result was a 35 dB suppression of the limit cycle amplitude with 20% secondary fuel injection.
Master of Science

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43

Christopher, Matthew L. "Real time control of combustor and engine processes." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17802.

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Aldawood, Ali Mohammad A. "Investigations of HCCI control using duel fuel strategies." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648890.

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45

Shlyubsky, Dmitry Iosifovich. "Flow control in an annular-return flow using combustion-driven actuators." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/36537.

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The annular-return flow and the utility of small-scale, combustion-based actuators for its control are investigated experimentally. The annular return flow is generated by an axial primary round jet, which impinges normally on a bounded end wall of a concentric tube, subsequently reverses direction, and exits the tube in a countercurrent flow to the primary jet. The combustion-based actuator generates a momentary (pulsed) jet that is produced by the ignition of a mixture of gaseous fuel and oxidizer in a small (cubic centimeter scale) combustion chamber. The operating frequency and the phase can be continuously varied by independently controlling the flow rate of the fuel/oxidizer and the ignition frequency. Two radially-opposing actuators are mounted on the wall of the annular return tube and are used to trigger flow transients that alter the global flow through strong feedback. The characteristics of the baseline flow and the effects of actuation are investigated using particle image velocimetry (PIV) as well as static and unsteady pressure measurements. The baseline flow is highly unstable, exhibiting very high rates of flow recirculation. The actuator jet acts as an azimuthal obstruction deflecting the primary jet and causing it to flow around the actuator jet. Furthermore, the interaction of the primary jet with the actuator jets generates large-scale circulation domains.

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Niva, L. (Laura). "Self-optimizing control of oxy-combustion in circulating fluidized bed boilers." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526221304.

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Abstract Energy production in combustion power plants is a significant source of anthropogenic carbon dioxide emissions. The targets of international climate agreements call for utilizing all available technologies to achieve rapid and cost-effective emission reductions. Carbon capture and storage is one of the possible technical solutions applied in combustion power plants. Circulating fluidized bed boilers have gained increasing popularity due to advantages in availability, emission control, fuel flexibility and option for using challenging fuels, and the possibility of using high-efficiency steam cycles. In the novel process of oxy-combustion, combustion air is replaced by a mixture of oxygen and recycled flue gas to facilitate the capture of carbon dioxide from the flue gas flow. Additional degrees of freedom become available for combustion control as the gas flow and composition can be controlled separately for fluidization and combustion purposes. In the research for this thesis, self-optimizing control was applied for the control structure design of a circulating fluidized bed boiler. Self-optimizing control offers a systematic tool for the early phases of control design, in which decisions have traditionally been made based on intuition, heuristics and previous experience. The self-optimizing control approach searches for controlled variables without a need for constant setpoint optimization when the process is affected by disturbances and implementation errors. Results presented in the thesis show that self-optimizing control can be applied in the control structure design of circulating fluidized bed combustion. A range of control structure alternatives were evaluated using steady-state approximations of a validated process model. For the novel oxy-combustion process, promising control structures were identified and could be dynamically demonstrated
Tiivistelmä Energiantuotanto polttovoimalaitoksissa on merkittävä hiilidioksidipäästöjen lähde. Kansainväliset ilmastotavoitteet edellyttävät kaikkien käytettävissä olevien teknologioiden hyödyntämistä päästövähennysten aikaansaamiseksi nopeasti ja kustannustehokkaasti. Hiilidioksidin talteenotto on yksi mahdollisista teknisistä ratkaisuista polttovoimalaitoksissa. Kiertoleijukattilat ovat saavuttaneet kasvavaa suosiota etuinaan hyvä käytettävyys, tehokas päästöjen hallinta, soveltuvuus erilaisten haastavienkin polttoaineiden hyödyntämiseen ja mahdollisuus tehokkaiden höyrykiertojen käyttöön. Uudessa happipolttoprosessissa palamisilma korvataan hapen ja kierrätetyn savukaasun seoksella, mikä mahdollistaa hiilidioksidin talteenoton savukaasuista. Kiertoleijupolton säädön kannalta vapausasteet lisääntyvät, sillä leijutukseen ja polttamiseen käytettävän kaasun määrää ja koostumusta voidaan säätää erikseen. Väitöstutkimuksessa käytettiin itseoptimoivaa säätöä kiertoleijukattilan säätörakenteiden suunnitteluun. Itseoptimoiva säätö tarjoaa systemaattisen menetelmän säätösuunnittelun alkuvaiheeseen, jossa päätöksenteko on perinteisesti tehty esimerkiksi intuition, heuristiikan ja aiempien ratkaisujen perusteella. Menetelmän tavoitteena on löytää säädettävät muuttujat, joiden asetusarvot eivät vaadi jatkuvaa optimointia, vaikka prosessiin vaikuttavat erilaiset häiriöt ja mittausvirheet. Väitöstutkimuksen tulokset osoittavat, että itseoptimoiva säätö soveltuu kiertoleijupolton säätörakenteiden suunnitteluun. Erilaisten säätörakenteiden toimivuutta arvioitiin käyttäen validoidun prosessimallin tasapainotilan approksimaatioita. Uudelle happipolttoprosessille löydettiin lupaavia säätörakenteita, joiden toimintaa voitiin demonstroida myös dynaamisesti

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47

Capelle, Jean-Yves. "Simulation of an algorithm for the active control of combustion noise." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42225.

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The simulation of an algorithm for the active control of combustion noise generated by a turbulent flame produced by an open burner is developed in this thesis. The simulation includes (1) an autoregressive model of real combustion noise, (2) a feedback loop based on the "observer" method, (3) a model of the transfer function between the acoustic driver and the sensor through the flame, and (4) a method to take into account the time-delay due the calculation of the algorithm. A practical implementation of the control strategy is also proposed. An attenuation of up to 40 dB is obtained in the 0 - 3000 Hz band, decreasing with the time-delay required for creation of the feedback signal. The influence of the order of the autoregressive model is studied, and it is shown that better results are obtained by increasing the order. The choices for the location of the activator and for the type of sensor are investigated and discussed. Further analytical research on the method of computing the feedback signal in the presence of time-delay is identified.
Master of Science

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48

Rumsey, Jennifer Weerts 1973. "Model-based active control of thermoacoustic instability in continuous combustion processes." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50464.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998.
Includes bibliographical references (p. 121-123).
Thermoacoustic instability is frequently found in continuous combustion processes in propulsion, power generation, and heating. Active control has been increasingly pursued in recent years to suppress the pressure oscillations which result from this instability, while maintaining performance objectives such as low NOx emission and high efficiency. This thesis considers the physics behind the thermoacoustic instability and utilizes a model based on the physics to understand the problem and design an active controller to suppress the instability. A one-dimensional, laminar combustor is modeled and a 1 kW bench-top combustor rig constructed for experimental validation of simulation results. The model considers the linear acoustic and flame dynamics, acoustic mode coupling, and actuator dynamics. Several model-based control designs including proportional, phase-lead, and LQG are presented and tested on the bench-top combustor using a 0.2 W loudspeaker as an actuator. Results show that the model-based controllers are effective in suppressing the instability, and that the simulation results accurately predict the response of the real system. Using the LQG controller, a settling time of as low as 23 milliseconds was obtained, significantly faster than those reported on similar setups. The nonlinear dynamics which leads to the limit-cycle behavior in real systems are investigated by looking at several "blackbox" type models of nonlinear behavior. The performance of the linear controllers on the nonlinear models is investigated and an explanation for their success given.
by Jennifer Weerts Rumsey.
S.M.

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Luzzato, Charles Michael Angelo. "Modelling and control of combustion instabilities with anchored laminar ducted flames." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/26224.

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This thesis deals with the derivation of new semi-analytical methods for the modelling of combustion instabilities in anchored laminar flame combustors. In a first part, through an analysis of the motion of the acoustic discontinuity in a ducted flame model, it shows that the movement of the flame induced discontinuity can lead to stability changes. For unstable combustors, it can also affect the amplitude of limit cycle oscillations. In a second part, the problems that are encountered when attempting to obtain the transfer functions for linearly unstable systems from within limit cycle are demonstrated. Indeed, under these circumstances, both the phase and amplitude of the unstable mode need to be corrected. Whilst the correction to the phase can easily be determined, the correction to the gain cannot, supporting the need for robust model based controllers or adaptive control methods which do not require system identification. Lastly, this thesis presents the derivation and implementation of the first asymptotic-based mathematical models which account for the flame motion, hydrodynamic field and acoustic field in an anchored ducted flame setup. This modelling exploits the difference in length scales associated with the flame, hydrodynamic field and acoustic waves. Unlike ducted flame models which omit the hydrodynamic field, this allows us to capture instability mechanisms such as Rayleigh-Taylor, or Darrieus-Landau instabilities, in the context of anchored laminar flames. This is done for two simplified configurations: a weakly conical flame shape, and a conical flame shape case with small mean heat release.

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Moscahlaidis, George. "Investigation of air control on chunkwood combustor." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/43101.

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Many small scale agricultural operations such as greenhouses, peanut drying and tobacco curing, use significant quantities of thermal energy. Direct combustion of biomass is a potential source of heat energy for those agricultural applications to substitute for the electricity or fossil fuels (principally LP gas) currently used. However, small scale combustion equipment often operates with low efficiency and high emissions. A prototype chunkwood combustor was installed and tested. The basis for controlling heat output, was the modulation of air supplied to the primary and secondary combustors. Exhaust gas CO and CO2 concentrations, combustor efficiency, and useful heat output were measured. The cleannest burn was achieved during a forty minute test, where 50 percent of stoichiometric air was introduced at the primary, and 170 percent at the secondary, for a total of 220 percent stoichiometric. The overall average CO/CO2 ratio for this test was 0.084, and 0.1 is considered to be an average rating for a combustion in a wood stove. Moreover, the efficiency during this test was 52 percent.
Master of Science

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