Dissertations / Theses on the topic 'Igniters'

Les systèmes d'allumage par étincelle sont généralement définis par l'énergie électrique utilisée pour leur fonctionnement. Cependant, la caractéristique physique qui affecte directement le processus d'allumage est l'énergie déposée dans le fluide par le système. Ce travail porte sur le développement de deux méthodologies proposées pour la caractérisation du dépôt d’énergie thermique de décharges électriques produites par différents systèmes d'allumage et de leur mise en œuvre au travers d’une étude paramétrique.Un dispositif expérimental est mis au point afin de développer et mettre en œuvre simultanément les deux techniques: une technique non optique, la calorimétrie à volume constant, et une technique optique, la SBOS (Speckle-based Background-Oriented Schlieren). L’étape de validation de ces méthodes est réalisée dans une configuration de référence d’un allumeur inductif alimentant une paire d'électrodes pointe-pointe.La calorimétrie à volume constant permet de mesurer un dépôt d'énergie thermique fournie au fluide par l’analyse de la montée en pression à l'intérieur d'une chambre de petit volume. Un suivi temporel du dépôt d’énergie pendant la décharge est ainsi obtenu. La mesure globale dans un volume de contrôle rend cette technique adaptable à tous types de décharges et d’électrodes. Le rapport entre le dépôt d'énergie thermique et l'apport d'énergie électrique représente l'efficacité du transfert d'énergie. Cette dernière est comprise entre 15 et 40 % pour la configuration de référence. Le dépôt d'énergie et l'efficacité du transfert d’énergie sont plus élevés à mesure que la pression et l'écart inter-électrode augmentent. Des essais avec un mélange inerte azote-propane montrent que le dépôt d'énergie est plus important en présence de carburant que dans l'air pur.La SBOS est une méthode optique permettant de quantifier les variations d’indice optique générés par le phénomène étudié. Le principe consiste à comparer des images d’un motif visualisé au travers du phénomène avec ce même motif en l’absence de phénomène. Cette technique est ici adaptée aux contraintes d’échelles spatiale et temporelle d’une décharge électrique. Une procédure de traitement a été développée afin d’obtenir les champs de masse volumique, de température et enfin l'énergie locale au moment de l'acquisition de l'image. Le volume du noyau chaud produit par le plasma et le dépôt d'énergie en sont déduits. Ces propriétés sont mesurées à différents instants de l'évolution du noyau. Dans la configuration de référence, il est montré que les températures dans le noyau chaud atteignent des valeurs plus élevées pour des distances inter-électrodes et des pressions plus élevées ou encore en présence de carburant. Le volume du noyau chaud est en revanche réduit lorsque la pression ou la distance inter-électrode augmente. Des mesures simultanées de dépôt d’énergie par les deux techniques montrent un très bon accord entre la SBOS et la calorimétrie.Enfin, les deux méthodologies sont adaptées à l'étude de différents systèmes d'allumage. Ainsi, deux allumeurs ont été testés, un allumeur à décharge radiofréquence multi filamentaires innovant et un allumeur capacitif typique d’un moteur d’hélicoptère. Pour ce dernier, le dépôt d'énergie est mesuré pour différentes pressions initiales et mélanges gazeux afin de simuler les conditions réelles du moteur. La technique SBOS est utilisée pour estimer la température dans le noyau chaud aux premiers instants de la décharge (jusqu'à 3500 K) et le dépôt d’énergie thermique qui est en bon accord avec la mesure calorimétrique. Le rendement ce cette décharge spécifique semble peu dépendant des conditions thermodynamiques du mélange et est estimé à 14%
Spark ignition systems are generally defined by the electrical energy input used to operate them. However, the physical characteristic that directly affects the ignition process is the energy deposit supplied to the fluid by the system. This work focuses on the development of two proposed methodologies for the characterization of the thermal energy deposit of electrical discharges produced by different ignition systems, and their implementation through a parametric study. An experimental device is developed for this purpose, using simultaneously a non-optical and an optical technique. The experimental techniques are first validated in a reference configuration: a pair of pin-to-pin electrodes with an automobile-type inductive ignition system.Constant volume calorimetry measures a thermal energy deposit supplied to the fluid via the pressure rise inside a reduced volume chamber. The ratio between thermal energy deposit and electrical energy supply represents the efficiency of energy transfer, which is between 15 and 40% for the reference configuration. Energy deposit and efficiency are higher as pressure and inter-electrode gap increase. Tests with an inert propane-nitrogen mixture show that energy deposit is greater in the presence of fuel than in clean air.SBOS (Speckle-based Background-Oriented Schlieren) is an optical method that quantifies changes in the optical index generated by the phenomenon under study. This technique has been adapted to the spatial and temporal specificity of an electrical discharge. Image-processing procedure has been developed to obtain density, temperature and local energy fields at the time of image acquisition. The volume of the hot kernel produced by the plasma and the energy deposit are deduced from it. These properties are measured at different times during the evolution of the kernel. Temperatures in the hot kernel reach higher values (up to 1400 K) at longer inter-electrode gaps and higher pressures, or in the presence of gaseous fuel. Energy deposit measurements performed by SBOS are in good agreement with calorimetry results.Finally, both methodologies are adapted to the study of different ignition systems. Two igniters were tested: an innovative multi-filament radiofrequency discharge igniter and a capacitive helicopter engine igniter. For the latter, the energy deposit is measured for different initial pressures and gas mixtures to simulate the actual engine conditions. The electrical energy input is 2 J, the electrical energy measured at the electrodes is 625 mJ and finally the thermal energy deposited in the gas is about 85 mJ. The estimated efficiency of 14% is not very pressure dependent. The SBOS technique is used to estimate the temperature in the hot kernel at the first moments of discharge (around 3700 K) and the thermal energy deposit, which is in good agreement with the calorimetric measurement

The intention with this project is to explore and open up the imagination, through investigating how text can be transformed into architecture. The outcome of the investigation during this project is a series of 9 architectural objects. The objects are independent from the text and could be thought of as ‘short-stories’.
Intentionen med detta examensarbete var att undersöka och öppna upp fantasin, genom att utforska hur text kan transformeras till arkitektur. Resultatet av detta utforskande projekt är en serie av 9 objekt. Objekten är oberoende av texten och kan ses som ’short-stories’ i sig själva.

Thesis (M.A.)--Trinity Evangelical Divinity School, 1994.
Abstract. Title page, abstract and initial chapter in English followed by Korean translation of the English work. Includes bibliographical references (leaf 11).

To realize supersonic combustion of hydrocarbons, an effective atomizer-igniter combination with the capabilities of fuel preheating, atomization, penetration, mixing, ignition and flameholding is desired. An original design concept incorporating these capabilities was built and tested at Virginia Tech, and was found to provide good penetration, effective atomization, and robust ignition and flameholding. Quiescent testing with kerosene and JP-7 provided initial performance data. The atomizer-injector design was then modified for insertion into a supersonic wind tunnel, and tested with kerosene in an unheated Mach 2.4 flow with typical freestream conditions of To = 280 K and Po = 360 kPa. Water injection was utilized in both cases for comparison and to analyze atomization behavior. In the quiescent environment, the regeneratively cooled plasma torch igniter was found to significantly increase electrode life while heating, atomizing, and igniting the liquid fuel. Jet breakup length was measured and characterized, and mean droplet size was estimated using an existing correlation. Several qualitative observations regarding quiescent combustion were made, including torch power effects and the process of flame formation. In the supersonic environment, the effect of fuel injection direction was analyzed. Best results were obtained when fuel was injected with a velocity component opposite to the direction of main tunnel flow. Repeatable ignition occurred in the supersonic boundary layer at the fuel stagnation location near the plasma torch plume. Direct, filtered, shadowgraph, and schlieren photographs, temperature measurements, and visible emission spectroscopy provided evidence of combustion and the details of the flame structure. The new atomizer-igniter design provided robust and reliable ignition and flameholding of liquid hydrocarbon fuels in an unheated supersonic flow at M=2.4, with no ramp, step, or other physical penetration into the flowpath.
Master of Science

As the flight speeds of aircraft are increased above Mach 5, efficient methods of propulsion are needed. Scramjets may be a solution to this problem. Supersonic combustion is one of the main challenges involved in the operation of a Scramjet engine. In general, both an igniter and a flameholder are needed to achieve and maintain supersonic combustion. The current work examines a plasma torch-strut combination as an igniter-flameholder. The plasma torch-strut combination was tested in the Virginia Tech unheated supersonic wind tunnel at Mach 2.4. Pressure and temperature sampling, filtered photography, and spectroscopic measurements were used to compare different test cases. These results provide both qualitative and quantitative results on how the combination responds to changes in the mass flow rate of fuel and the power to the plasma torch. The key conclusions of the work were the following: 1. Tests showed that an exothermic reaction takes place. 2. The amount of heat release increases with an increase in the mass flow rate of fuel. 3. The plasma torch-fuel injector interaction caused the heat release to be well above the tunnel floor and sometimes off the strut centerline 4. One change in the fuel injector pattern caused more temperature rise near the floor of the tunnel. 5. The flow penetration height of the plasma torch alone was reduced by the fuel-plasma torch interaction. 6. Moving the strut upstream reduced the measured temperature rise at a fixed downstream location, but increased the penetration height of the plasma torch. 7. The computed heat release was found to be small compared to the potential heat release from all the fuel burning. 8. The amount of temperature rise caused by the fuel is not greatly affected by the power to the plasma torch.
Master of Science

A newly designed liquid fuel (kerosene) aeroramp injector/plasma igniter was tested in cold flow using the Virginia Tech supersonic wind tunnel at Mach 2.4. The liquid fuel (kerosene) injector is flush wall mounted and consists of a 2 hole aeroramp array of impinging jets that are oriented in a manner to improve mixing and atomization of the liquid jets. The two jets are angled downstream at 40 degrees and have a toe-in angle of 60 degrees. The plasma torch used nitrogen and air as feedstocks and was placed downstream of the injector as an ignition aid. First, schlieren and shadowgraph photographs were taken of the injector flow to study the behavior of the jets, shape of the plume, and penetration of the liquid jet. The liquid fuel aeroramp was found to have better penetration than a single, round jet at 40 degrees. However, the liquid fuel aeroramp does not penetrate as well as an upstream/downstream impinging jet in a plane aligned with the flow. Next, the Sauter mean droplet diameter distribution was measured downstream of the injector. The droplet diameter was found to vary from 21 to 37 microns and the atomization of the injector does not appear to improve beyond 90 effective jet diameters from the liquid fuel aeroramp. These results were then used to decide on an initial location for the plasma torch. The combined liquid injector/plasma torch system was tested in an unheated (300 K) Mach 2.4 flow with a total pressure of 345 kPa. The liquid fuel (kerosene) volumetric flow rate was varied from 0.66 lpm to 1.22 lpm for the combined liquid injector/plasma torch system. During this testing the plasma torch was operated from 1000 to 5000 watts with 25 slpm of nitrogen and air as feedstocks. The interaction between the spray plume and the plasma torch was observed with direct photographs, videos, and photographs through an OH filter. It is difficult to say that any combustion is present from these photographs. Of course, it would be surprising if much combustion did occur under these cold-flow, low-pressure conditions. Differences between the interaction of the spray plume and the plasma torch with nitrogen and air as feedstocks were documented. According to the OH wavelength filtered photographs the liquid fuel flow rate does appear to have an effect on the height and width of the bright plume. As the liquid fuel flow rate increases the bright plume increases in height by 30% and increases in width slightly (2%). While, a decrease in liquid fuel flow rate resulted in an increase in height by 9% and an increase in width by 10%. Thus, as the liquid fuel flow rate varies the width and height of the bright plume appear to always increase. This can be explained by noticing that the shape of the bright plume changes as the liquid fuel flow rate varies and perhaps anode erosion during testing also plays a part in this variation of the bright plume. From the OH wavelength filtered photographs it was also shown that the bright plume appears to decrease in width by 9% and increase in height by 22% when the plasma torch is set at a lower power setting. When air is used as the torch feedstock, instead of nitrogen, the penetration of the bright plume can increase by as much as 19% in width and 17% in height. It was also found that the height and width of the bright plume decreased slightly (2%) as the fuel flow rate increased when using air as the torch feedstock. Testing in a hot-flow facility is planned.
Master of Science

Includes bibliographical references (leaves 61-63).
Homogeneous Charge Compression Ignition (HCCI) is a new internal combustion system that promises high efficiency and dramatically reduced nitrous oxide (NOJ and particulate matter (PM) emissions when compared to current spark ignition (SI) and compression ignition (CI) engine technologies. In its simplest form, HCCI can be described as lean autoignition of a homogeneous fuel/air mixture that occurs without a flame front. HCCI can in theory be achieved using almost any fuel, provided that it evaporates readily and has a short enough ignition delay that it can be made to autoignite under the conditions typically found in an IC engine. Basically HCCI incorporates the best features of a SI (petrol) and CI (diesel) engine. Like in a SI engine, the fuel and air in the cylinder is allowed to be well mixed before the onset of combustion which promotes cleaner burnng (Low PM) and like in a CI engine the engine is operated overall fuel-lean and therefore has no throttling losses and near zero NOx emissions. The mixture is also compression ignited in the same way as in a CI engine. This causes combustion to occur simultaneously throughout the combustion chamber and thus no flame front is present.

Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, March 2004.
Thesis advisor(s): Barry Frew, Dale Courtney. Includes bibliographical references (p. 79). Also available online.

Motivated by the shock ignition approach to improving the performance of inertial fusion targets, we make a series of studies of the stability of hydrodynamic shock waves. We first examine the behaviour of shocks moving through perturbations in background fluid in planar and 2D converging geometries, representing the ‘ignition’ shock moving through strongly perturbed material. To do this we follow the behaviour of finite amplitude perturbations on a 2D spherically converging shock wave, through convergence, reflection at its minimum radius and then into the expansion phase. We then extend this to pressure perturbations for converging shocks, representing asymmetries in the drive profile. These are then extended to 3D where we examine a uniquely 3D asymmetry, collapse and reflection of perturbed shock fronts without axial symmetry. We find that finite amplitude perturbations are transferred with little change through convergence into expansion, recovering their approximate ingoing form and find that shock fronts are robust against a range of asymmetries, specifically that the shock front is broadly stable against moderate perturbation, with only minor deviations from the symmetric behaviour. Even under fairly extreme, 3D perturbations in multiple parameters in convergent geometry the shock front remains robust and transfers with little change through convergence into expansion and recovers its approximate ingoing form. This stability of shock waves is at the root of the robustness of shock ignition and suggests this robustness is fully 3D.

Studies are presented that examine the development of combustion in an initially non-reacting methane jet after ignition at a downstream location. Image measurements depicting the axial location of a fixed energy ignition source that permits transient flame propagation back to the nozzle are presented. The results from the experimental investigations are discussed. Nine different cases were investigated in order to determine the major parameters that impact the axial location of the ignition source at which flame propagation back to the burner was permitted. When the ignition source was located at larger axial distances than those indicated, flame propagation upstream to the burner was not possible and, instead, the flame blew out. The Reynolds number of the jet, the scalar field and the air co-flow magnitude were investigated for their contributions. A standard digital video camera was used in order to film the ignition of the jet and to determine the farthest axial location from the burner at which upstream flame propagation was possible. With the aid of computer software, the height for each case was determined. Conclusions to the effect these parameters had on the axial location are discussed as well as the implications for the physics governing the process.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.
Includes bibliographical references (p. 59).
Experiments were carried out to collect in-cylinder pressure data and microphone signals from a single-cylinder test engine using spark timings before, at, and after knock onset for four different octane-rated toluene reference fuels. This data was then processed and analyzed in various ways to gain insight into the autoignition phenomena that lead to knock. This was done to develop a more fundamentally based prediction methodology that incorporates both a physical and chemical description of knock. The collected data was also used to develop a method of data processing that would detect knock in real time without the need to have an operator listening to the engine. Bandpass filters and smoothing techniques were used to process the data. The processed data was then used to determine knock intensities for each cycle for both the cylinder pressure data and microphone signal. Also, the rate of build-up before reaching peak amplitude in a bandpass filtered pressure trace was found. A trend was found showing that cycles with knock intensities greater than 1 bar with rapid build-up (5-10 oscillations) before reaching the peak are the type the cycles whose autoignition events lead to engine knock.
(cont.) The cylinder pressure knock intensities and microphone knock intensities were plotted and then fit with a linear trendline. The R2 value for these linear trendlines will transition from considerably lower values to values greater than 0.85 at the spark timing of knock onset. It is believed that the higher cylinder pressure knock intensities, in conjunction with the faster build-up of 5-10 oscillations before reaching peak, helps to explain the knock phenomena. It supports conclusions from previous works that the end gas contains one or more hot spots that autoignite in sequence causing pressure gradients that can trigger rapid pressure oscillations. These pressure oscillations can cause block and head vibrations that lead to audible noise outside the engine.
by Bridget M. Revier.
S.M.

O principal objetivo dessa dissertação é investigar o mecanismo físico de funcionamento do ignitor gás dinâmico para possibilitar uma partida suave do motor L15 e também conhecer as propriedades da chama gerada pelo ignitor, o que possibilirá alteração de parâmetros de operação do ignitor para outros motores. Será apresentada nesse trabalho uma investigação teórica do mecanismo de aquecimento do gás injetado no ressonador do ignitor gás dinâmico, um modelamento matemático para esse mecanismo, incluindo uma rotina de cálculo e ainda, a comparação com os resultados de ensaios. Serão investigados experimentalmente o tempo de ressonância, e como diminuí-lo e a razão de mistura da chama gerada pelo ignitor, de forma que uma chama rica em combustível seja alcançada.

Forskning inom motorutveckling bedrivs för att möta kommande emissionskrav och samtidigt minska bränsleförbrukningen. Kommande förbud mot dieseldrivna fordon planeras i flera städer runt om i världen. Alternativa bränsle som exempelvis naturgas ses som en lovande ersättning även för tunga fordon. Metan som är huvudkomponenten av naturgas har en fördelaktigt förhållande mellan väte och kol vilket gör den attraktiv för CO2-reducering. Hur som helst, bränslets låga cetantal och den höga aktiveringsenergin som krävs för att tända naturgas förutsätter tändstiftsantändning.En fördel av att använda en encylindrig motor inom forskning är möjligheten att studera fenomen utan negativa gasväxlingsinteraktioner från intilliggande cylindrar. Jämfört med en fullmotor möjliggörs även ett snabbare utbyte av motordelar samt lägre bränsleförbrukning.Fokus för detta examensarbete var genomförandet av ett flexibelt bränslesystem för en tändstiftsantänd encylindrig motor. Motorn är en tändstiftsantänd Scania 9 liters som modifieras för encylinder körning. Flexibilitet som t.ex. laddningshomogenitet, selektiv fyllning av inloppsporter och förberedelser för direktinsprutning av flytande bränsle realiserades. För enkel användning är motorn styrd av en eftermarknadsmotorstyrenhet som använder ett användarvänligt grafiskt gränssnitt för ändring av driftsparametrar. Säkerhetshänsyn vid blandning av gasformiga bränsle och luft långt innan inloppsporterna har implementerats.
Most of the fundamental research in internal combustion engines is driven by the ever-increasing stringency of emissions regulations along with the need for increased fuel economy. The proposed ban on diesel vehicles in several cities around the world combined with extensive availability, has made natural gas a promising substitute even for heavy-duty applications. The high hydrogen-to-carbon ratio of methane, the major component of natural gas, makes it attractive from an emissions reduction perspective. CO2 emissions from natural gas combustion are particularly low. However, the low cetane number and high activation energy required to ignite natural gas, requires spark-ignition.In a research setting, it is often advantageous to have a single cylinder engine. The main benefit is the ability to study phenomena without adverse interactions which multi-cylinder operation may cause. This is especially important for gas-exchange studies. Quicker replacement of parts and lower fuel consumption are secondary benefits.The focus of this thesis was the implementation of a flexible fueling system for a single cylinder spark-ignited engine. The engine is a Scania 9-liter spark-ignited engine modified for single cylinder operation. Flexibility in terms of charge homogeneity, selective intake port filling and provisions for liquid fuel direct injection have been provided. For ease of use, the engine is controlled by an aftermarket engine control unit with a graphical user interface for configuration. Safety considerations when mixing gaseous fuels and air well upstream of the intake ports have been implemented.

Regeringens lagstiftare ökar ständigt kraven på att kontrollera utsläppen från tunga fordon för att upprätthålla hållbar miljö. Samtidigt ökar också behovet av snabb respons och lägsta bränsleförbrukning ur kundens perspektiv. För att möta efterfrågan måste den integrerade kontrollarkitekturen göras robust och snabb genom att använda optimalt luftmassflöde och EGR i cylindern för att få önskat vridmoment genom att upprätthålla luftbränsleförhållandet (AFR) som stökiometri i alla driftsområden. För att upprätthålla temperaturen och trycket i avgassamlaren har EGR (exhaust gas recirculation) införts i de gnisttändda motorerna, vilket förbränner de återcirkulerade avgaserna. I denna uppsats har en modellbaserad styralgoritm utvecklats genom modellering av trottel, EGR och waste-gate ventil med korsfrekvenser. Algoritmen syftar till att uppnå det önskade luftflödet och EGR så fort som möjligt under transienter vid alla driftspunkter (motorvarvtal och last). För att utvärdera kontrollstrategin modellerades en femcylindrig motor i programmet GT-SUITE. De modellbaserade regulatoralgoritmerna är utvecklade i SIMULINK genom att upprätta en kommunikationslänk med funktionell Mock-Up Interface (FMI). Den modellbaserade reglering är framkopplad med en förstyrning i form av en "Gain Schedulerad" PID regulator vilken är integrerad med modellen till en kaskadreglering. En serie av transienta steg har analyserats genom att steg i last gjordes vid olika motorvarvtal. Den algoritm som utvecklas gav tillfredsställande resultat där svarstiden har ökats och oscillationerna dämpas i större utsträckning.
Government legislators constantly increasing the demands on controlling the emission from heavy-duty vehicles for maintaining sustainable environment. At the same time, from the customer's perspective, a much needed demand for fast response and minimal fuel consumptions is also increasing. To get the desired torque, the control architecture has to be made robust and fast by using optimal air mass flow and EGR rate into the cylinder by maintaining the Air-Fuel Ratio (AFR) at stoichiometry at all operating regions. In order to maintain the temperature and pressure in the exhaust manifold, Exhaust Gas Recirculation (EGR) valve has been introduced in the spark- ignited engines which feeds back the burned exhaust gases into the intake manifold. In this thesis, a Model-based control algorithm has been developed by modelling throttle, EGR and waste-gate actuators with cross sensitivities. The algorithm aims at achieving the requested air flow and EGR rate as fast as possible during the transients at all operating points (Engine Speed and load). To evaluate the control strategy, a five-cylinder engine was modelled in GT-SUITE software. The model-based controller algorithms is designed in SIMULINK by establishing a communication link using Functional Mock-Up Interface (FMI). The Model-based controller is pre-fed with a pre- filter/pre-controller using Gain Scheduling PID algorithm which is integrated to form a closed loop cascade controller. Series of analysis has been done in transient domain by varying the load requests and the operating points (Engine Speed). The algorithm that is developed gave satisfactory results where the response time has been increased and the oscillations are damped to a greater extent.

The first integrated, flush-wall, aero-ramp-fuel-injector/plasma-torch igniter and flame propagation system for supersonic combustion applications with hydrocarbon fuels was developed and tested. The main goal of this project was to develop a device which could be used to demonstrate that the correct placement of a plasma-torch-igniter/flame-holder in the wake of the fuel jets of an aero-ramp injector array could make sustained, efficient supersonic combustion with low losses and thermal loading possible in a high enthalpy environment. Three phases of research were performed to develop the device using the supersonic cold flow facilities at Virginia Tech. The experimental investigations included some of the following methods: shadowgraphs, surface oil flow, pressure-sensitive paint, high- or low-speed photography, aerothermodynamic sampling, and spectroscopy. During this research effort, a new mixing parameter was also developed to quantify the injector plume mass fraction concentration values using successive profiles of ambient or heated air as the injectant. The first phase of the research effort was conducted at Mach 3.0 at a static pressure and temperature of 0.19 atm and 101 K. This phase involved component analyses to improve on the designs of the aero-ramp and plasma-torch as well as address integration and incorporation difficulties. The information learned from these experiments lead to the creation of the first prototype integrated aero-ramp/plasma torch design featuring a new simplified four-hole aero-ramp design. The second phase of the project consisted of experiments at Mach 2.4 involving a cold-flow mixing evaluation of the new aero-ramp design and a resizing of the device for incorporation into a scramjet flow path test rig at the Air Force Research Laboratories (AFRL). Experiments were performed at a static pressure and temperature of 0.25 atm and 131 K, and at injector-jet to freestream momentum flux ratios ranging from 1.0 to 3.3. Results showed the aero-ramp to mix at a considerably faster rate than the injector used in the AFRL baseline combustor configuration due to high levels of vorticity created by the injector array. In addition, the plume of the aero-ramp lifted off the test section wall without trapping a secondary core inside the shear layer near the surface, unlike the earlier nine-hole aero-ramp arrays. The mitigation of the secondary fuel core leads to a lower level of combustion near the surface and a lower potential for thermal loading on the wall. The last phase of the research involved testing the final device design in a cold-flow environment at Mach 2.4 with ethylene fuel injection and an operational plasma torch with methane, nitrogen, a 90-percent nitrogen 10-percent hydrogen (by volume) mixture, and air feedstock gases. Experiments were performed with injector jet to freestream momentum flux ratios ranging from 1.4 to 3.3, and 1.2 with the plasma torch at a nominal power level 2000 watts. Overall, the final integrated design showed a high mixing efficiency and a higher potential for repeatable main fuel ignition and flame propagation with the plasma torch placed at the middle of the three downstream torch stations tested (x/dinjector = 8 downstream from the center of the injector area), with nitrogen as the torch feedstock. Furthermore, the integrated device created a sustained flame, demonstrating main fuel ignition in a cold and low pressure supersonic environment with a plasma-torch. Local intensity distributions of the major excited species generated from the interaction of the plasma-torch with the main fuel plume were also identified with a spectrometer. As a result of the research and development process, an injector block for scramjet combustor experiments consisting of four integrated aero-ramp-injector/plasma-torch-igniters was created for near future tests at the AFRL.
Ph. D.

LAUNCH is a multi-organizational initiative led by NASA, Nike, USAID, and Department of State to seek and accelerate disruptive innovations to address intractable sustainability issues. The focus of this embedded case study is the evolution of the idea of LAUNCH through the lens of group practice. The empirical evidence includes detailed documentation of artifacts, group practice constructs, interaction and process maps for the five embedded cases, sentiment analysis of 25,000 email interactions, as well as a unique contribution of insights from a LAUNCH co-founder and participant-observer that were continually woven back into the conduct of LAUNCH group practice. The study looks at the conduct of group practice in a continual pull and tug across four construct continuums: tall-flat governance, expedite-explore deliberations, control-create idea generation, and electron-proton behaviors. Process maps of the group activities and artifacts demonstrate the continual tension along these continuums, which is supported by sentiment analysis of email interactions among group members. Plotted over time, sentiment analysis illustrates successive waves of positive and negative interactions during deliberation around development and implementation of ideas and processes. These findings are described using scientific metaphors from atomic physics and quantum mechanics. The behaviors of individuals within the LAUNCH core group resemble subatomic particle behaviors, while the group interactions sentiments resemble quantum theory wave behaviors, such as light waves. The quantum revolution resolved the scientific dilemma of wave and particle behaviors of matter and energy" which is much like the duality of the conduct and behavior of individuals and the interconnected interactions in group practice, and its effect on the rise and fall (wave) of ideas. The particle-wave duality in quantum theory sparked the big idea for a quantum theory of social dynamics, proposed in this study. The proposed theory applies to the conduct of group practice, behaviors exhibited by individuals and groups of individuals, and the generation of ideas evoked by disruption through social interactions. The proposed theoretical tenets may shed light on the broader understanding of the social dynamics embedded in group practice: 1) group practice is convened around and bound by a shared goal " the strong force; 2) individual actions influence the conduct of group practice in positive and negative ways; 3) individuals convened in group practice interact with one another through interconnected wave patterns of sentiment that affect the rise and fall of ideas; 4) individual behaviors and group interactions fluctuate in dynamic patterns of interference that disrupt the conduct of group practice; 5) individuals and groups of individuals mutually reinforce one another and amplify ideas with in-phase behaviors, while obstructing people and progress with out-of-phase behaviors; 6) disruptive thinking is a discomfort factor necessary for idea generation in a socially constructed world; and 7) creativity that arises in response to disruption can evoke idea-generation, new knowledge, and new ways of knowing.
Ph. D.

Thesis (M.S.)--West Virginia University, 2005.
Title from document title page. Document formatted into pages; contains xi, 79 p. : ill. Includes abstract. Includes bibliographical references (p. 67-70).

Las crecientes exigencias de la industria están cambiando la forma en que entendemos la sociedad y el entorno en el que vivimos. Frente a la necesidad de un comercio rápido y globalizado, están emergiendo varios problemas de sostenibilidad. Por una parte, ciertos sectores resultan favorecidos, como es el caso del transporte y su radical incremento de actividades. Por otra parte, esto causa un impacto negativo considerable en los ecosistemas terrestres. En este marco, los efectos negativos de la contaminación ambiental y sonora están llegando a límites realmente preocupantes, siendo estos especialmente visibles en los principales núcleos urbanos, donde las autoridades están incluso restringiendo la circulación de los vehículos térmicos. Particularmente, el ruido producido por la quema del combustible en vehículos propulsados por motores de combustión interna alternativos, siendo una de las principales fuente acústicas por delante de otras como la aviación o el ferrocarril, está siendo objeto de recientes estudios para reducir sus efectos perjudiciales en la población. El objetivo principal de esta tesis se centra en el estudio y caracterización de la combustión como fuente de emisiones acústicas. Concretamente, esta investigación tiene como propósito dar respuesta a cuáles son los fenómenos físicos asociados a la generación del ruido en motores de encendido por compresión, así como proponer algunas directrices que ayuden a entender y mejorar -desde el punto de vista de emisiones acústicas y consumo- el diseño de los motores actuales. En una primera aproximación, se recurre a técnicas experimentales de medida para, con el registro de la presión instantánea dentro de la cámara de combustión, caracterizar el origen de las perturbaciones acústicas. A pesar de que la información aportada por estos métodos es relevante, existen limitaciones para recrear la espacialidad del campo acústico y, por tanto, dificultan la comprensión de los fenómenos no estacionarios asociados a este. Por esta razón, en posteriores estudios se recurre al uso de la dinámica de fluidos computacional o CFD, superando así las limitaciones de las técnicas experimentales y permitiendo una visualización completa del problema. Como paso previo e indispensable, se procede a implementar y validar del modelo CFD para asegurar una buena precisión en los resultados y un tiempo de cálculo razonable. La aplicación de métodos de análisis en frecuencia y descomposición modal han permitido estudiar el campo de presiones en el interior de la cámara y así entender mejor su comportamiento. De este modo, ha sido posible encontrar relaciones entre la combustión y la respuesta espectral del campo acústico interno. Los patrones de oscilación de la presión muestran que las estructuras más energéticas, y que por tanto contribuyen a la emisión acústica en mayor medida, están centradas en estructuras macroscópicas de tamaño similar a la geometría de la cámara. Además, se ha demostrado que la posición de la ignición del combustible tiene un efecto directo sobre la amplitud de los modos resonantes y su distribución espacial. Por último, en cuanto a la evaluación de estrategias para mitigar el ruido, se proponen distintos estudios en los que se analizan las tendencias en la emisión acústica al modificar la fuente sonora, mediante la configuración de la inyección y la geometría del sistema de combustión.
Les creixents exigències de la indústria estan canviant la forma en què entenem la societat i l'entorn en què vivim. Davant la necessitat d'un comerç ràpid i globalitzat estan sorgint diversos problemes de sostenibilitat que, per una part afavoreixen que sectors com el del transport incrementen les seues activitats de forma radical, però que per l'altra, causen un impacte negatiu en els ecosistemes terrestres. En aquest context, els efectes negatius de la contaminació ambiental i sonora estan arribant a límits realment preocupants, sent aquests especialment visibles als principals nuclis urbans on les autoritats estan inclús restringit la circulació dels vehicles tèrmics. Particularment, el soroll causat per la crema de combustible en vehicles propulsats per motors de combustió interna alternatius, sent una de les principals fonts acústiques per davant d'altres com l'aviació o el ferrocarril, està sent objecte de recents estudis per tal de reduir els efectes perjudicials en la població. L'objectiu principal d'aquesta tesi es centra en l'estudi i caracterització de la combustió com a font d'emissions acústiques. Concretament, aquesta investigació té com a propòsit donar resposta a quins són els fenòmens físics associats a la generació de soroll en motors d'encès per compressió, així com proposar algunes directrius que ajuden a entendre i millorar -des del punt de vista de les emissions acústiques i consum- el disseny dels motors actuals. En una primera aproximació, es recorre a tècniques experimentals de mesura per a, amb el registre de la pressió instantània en la cambra de combustió, caracteritzar l'origen de les pertorbacions acústiques. Tot i que la informació aportada per aquests mètodes és rellevant, existeixen limitacions per a reconstruir l'espacialitat del camp acústic i, per tant, dificulten la comprensió dels fenòmens no estacionaris associats a aquest. Per aquesta raó, en posteriors estudis es recorre a l'ús de la dinàmica de fluids computacional o CFD, superant així les limitacions de les tècniques experimentals i permetent una visualització completa del problema. Com a pas previ i indispensable, es procedeix a implementar i validar el model CFD per assegurar una bona precisió en els resultats i un temps de càlcul raonable. L'aplicació de mètodes d'anàlisi en freqüència i descomposició modal ha permès estudiar el camp de pressions en l'interior de la càmera i així entendre millor el seu comportament. D'aquesta forma, ha sigut possible trobar relacions entre la combustió i la resposta espectral del camp acústic intern. Els patrons d'oscil·lació de la pressió mostren que les estructures més energètiques, i que per tant contribueixen a l'emissió acústica en major mesura, estan centrades en estructures macroscòpiques de grandària similar a la geometria de la càmera. A més, s'ha demostrat que la posició de la ignició del combustible té un efecte directe sobre l'amplitud dels modes ressonants i la seua distribució espacial. Per últim, pel que fa a l'avaluació de diverses estratègies per a mitigar el soroll, es proposen distints estudis en què s'analitzen les tendències en l'emissió acústica en modificar la font sonora mitjançant la configuració de l'injector i la geometria del sistema de combustió.
The ever-increasing demands of industry are changing the way we understand society and the environment in which we live. In the face of the need for rapid and globalised trade, a number of sustainability issues are emerging which, on the one hand, encourage sectors such as transport to radically increase their activities, but, on the other hand, cause a negative impact on terrestrial ecosystems. In this context, the negative effects of environmental and noise pollution are reaching really worrying limits, these being especially visible in the main urban areas where the authorities are even restricting the circulation of vehicles powered with thermal engines. In particular, the noise produced by the fuel burning in vehicles powered by reciprocating internal combustion engines, being one of the main acoustic sources ahead of others such as aviation or railways, is being the focus of recent studies to reduce its harmful effects on the population. The main objective of this thesis focuses on the study and characterization of combustion as a source of noise emissions. Specifically, this research focuses on addressing the physical phenomena associated with noise generation in compression-ignited engines, as well as proposing some guidelines in order to better understand and improve -from the point of view of noise emissions and fuel consumption- the design of current engines. In a first approach, experimental techniques are used to characterise the source of the acoustic disturbances by recording the instantaneous pressure inside the combustion chamber. Although the information provided by these methods is relevant, there are some limitations to recreate the spatiality of the acoustic field and, therefore, make it difficult to understand the non-stationary phenomena associated with it. For this reason, in subsequent studies the Computational Fluid Dynamics or CFD approach is utilized, thereby overcoming the limitations of experimental techniques and allowing a complete visualization of the problem. As a preliminary and indispensable step, we proceed to implement and validate the CFD model to ensure a good accuracy in the results and a reasonable calculation time. The application of frequency analysis and modal decomposition methods has made it possible to study the pressure field inside the chamber and thus better understand its behaviour. In this way, it has been possible to find relationships between the combustion and the spectral response of the internal acoustic field. The pressure oscillation patterns show that the most energetic structures, and thus contributing the most to the acoustic emission, are centred on macroscopic structures of similar size to the chamber geometry. In addition, the ignition position of the fuel has been shown to have a direct effect on the amplitude of the resonant modes and their spatial distribution. Finally, regarding the evaluation of different strategies for mitigating noise, different studies are proposed in which the trends in noise emission are analysed by modifying the sound source through the injection configuration and the geometry of the combustion system.
Gómez Soriano, J. (2018). Computational assessment of combustion noise of automotive compression-ignited engines [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/112726
TESIS

As a supplier of sustainable transport solutions, Scania manufactures gas engines. Fueled with biogas, they offer a significant decrease in carbon dioxide emissions compared to standard diesel. The gas engines are fitted with a three-way catalytic converter, which converts hydrocarbons, carbon monoxide and nitrogen oxides from the combustion process to substances with less adverse effects. A misfire is an undesired lack of combustion. They are typically caused by faults in the ignition system, fuel system or by an unsuitable air/fuel ratio. If a misfire occurs, fuel may enter the catalytic converter where it combusts. This increases the temperature in the catalyst to above its design limit, permanently damaging it. The excess fuel also causes increased hydrocarbon emissions. Emission legislation mandates that malfunctions causing excess emissions must be continuously monitored by the vehicle. The misfire detection on engines sold in the North American market must comply with the stringent CARB legislation. It may also be assumed that upcoming European legislation will be stricter. Furthermore, current production engines use dedicated hardware to detect misfires. A misfire detection method that uses signals from sensors already fitted to the engine could result in cost savings. A literature study was performed, after which suitable methods to proceed with were chosen. Data was collected in an engine test cell, and was analyzed offline. Misfire detection methods based on exhaust pressure sensors and knock sensors were evaluated. A detection algorithm developed for Scania’s diesel engines was evaluated. With some modifications, it appears suitable for gas engines. Simplified variants of this method were developed with promising results. A method based on Fourier transform of a low-order frequency showed excellent results, perhaps at the expense of processor load. A knock sensor based method also showed some promise in detecting misfires. However, the position of the knock sensors appears critical, and further investigation is required. Classified parts of this thesis are replaced by the symbol □. Some plot axes are erased for the same reason.
Som en leverantör av hållbara transportlösningar tillverkar Scania gasmotorer. Tankade med biogas minskar dessa utsläppen av koldioxid avsevärt jämfört med standarddiesel. Gasmotorerna är utrustade med en trevägskatalysator som omvandlar kolväten, kolmonoxid och kväveoxider till mindre skadliga ämnen. En misständning innebär utebliven förbränning. Detta beror typiskt sett antingen på fel i tändsystemet, fel i bränslesystemet eller felaktigt luft/bränsleförhållande i cylindern. Om en misständning sker kan oförbränt bränsle ta sig till katalysatorn, där bränslet förbränns. Detta ökar temperaturen i katalysatorn, vilket kan försämra dess prestanda. Det kan även leda till ökade utsläpp av kolväten. Fel som kan påverka utsläpp måste enligt lagstiftning kontinuerligt övervakas av fordonet. Scanias gasmotorer kan komma att säljas på den nordamerikanska marknaden, där kraven på misständningsdetektering är striktare än i övriga världen. Det kan även förväntas att kommande europeisk lagstiftning kommer att vara strängare än tidigare. Tekniken för misständningsdetektering på nuvarande gasmotorer använder dedikerad hårdvara. En misständningsdetekteringsmetod som använder signalen från befintliga givare kan leda till kostnadsbesparingar. Efter en litteraturstudie valdes lämpliga detekteringsmetoder ut för vidare undersökning. Data inhämtades från körningar i provcell och analyserades offline. Metoder baserade på avgasmottryck och på knacksensordata utvärderades. En algoritm utvecklad för misständningsdetektering på Scanias dieselmotorer utvärderades. Med vissa modifieringar verkar den gå att tillämpa på gasmotorer. Förenklade varianter av denna metod utvärderades, även dessa med lovande resultat. En metod baserad på Fouriertransform av lägre ordningens frekvenser i avgastrycksignalen visade utmärkta resultat, eventuellt på bekostnad av processorlast. En knacksensorbaserad metod uppvisade lovande resultat. Dock verkar placeringen av knacksensorerna vara kritisk, och vidare utvärdering krävs. Hemligstämplade delar i denna rapport har ersatts av symbolen □. Axelvärden i vissa figurer har raderats av samma skäl.

Five plasma jet ignitor designs were tested on a Waukesha ASTM-CFR engine fueled with natural gas. The pollutant emissions, fuel and air flow rates and dynamic cylinder pressure were measured for the full range of Air/Fuel ratios. From these measurements the indicated power and specific fuel consumption were calculated. The energy for the ignitors was provided by a variable high energy ignition system, and each ignitor was supplied with 0.00, 0.08, 0.32, 0.72 and 1.28 Joules of energy in addition to that provided by the standard ignition coil. To differentiate between the benefits gained by use of the plasma jet ignitors and those due to the higher ignition energies, an ordinary spark plug was also tested with added ignition energies. The goal of the experiment was to find an ignitor that could be used to extend the lean operating limit of a natural gas fueled engine, so that the emission of NO_x, and other pollutants could be reduced. The following table shows the optimum pollutant emission reductions achieved by the use of the most effective plasma jet ignitor and the high energy spark plug compared with the emissions from the engine when operated with the standard equipment spark plug near stoichiometric. The plasma jet ignitor for which the results are displayed in this table consisted of an 83 mm³ cavity and a 118 mm³ ejector, both of which were insulated with ceramic cylinders.
Master of Science

Spark-ignited engines are known to produce PM composed of solid, volatile or semi-volatile particles including spheres of carbon soot formed into agglomerates, other forms of carbonaceous particles, metal particles and charred droplets of engine oil. In this thesis, detailed observation has revealed that SI PM is partly composed of fully-formed carbon nanotubes and fullerenes in addition to known particle types previously presented in the literature. The purpose of this work is to ascertain the shape and size of particulate matter being emitted by SI engines. In this thesis, PM thermophoretic sampling and transmission electron microscopy were used to collect and analyze engine soot samples, respectively. Furthermore, the operation of the thermophoretic sampling device used in engine PM sample collection was characterized to identify the sampling efficiency based on particle deposition and sampling biases based on differences in particle thermoconductivity for various forms of carbon such as turbostratic soot, crystalline carbon nanotubes and calcium. In general, the efficiency of the TPS method was roughly estimated to be 30-80% efficient based on experimental results. In this thesis, carbon nanotubes and fullerenes have been identified as being emitted from in-use, spark-ignited natural gas and gasoline burning auto-rickshaw engines tested in New Delhi, India. Emission of fullerenes and CNTs was on the order of 10% +/- 7% of the non-volatile particulate matter. Agglomerates, dense spherical particles believed to be charred engine oil, and unidentified or compound particles were also cataloged. Confirmation that nanotubes are being produced by SI engines was achieved using PM samples collected from the Ricardo Hydra laboratory test engine at the University of British Columbia, Clean Energy Research Centre. Under more controlled conditions than can be achieved sampling in-use vehicles, SI engine PM is found to be a complex collection of dense, dark (possibly charred oil) spheres, small primary particle agglomerates, small particle deposits, volatile droplets, carbon nanotubes and fullerenes and large ‘other’ particles. High resolution TEM confirmed tube-shaped particles to be fully formed multi-walled carbon nanotubes.

This thesis details and reviews the development of a Pre-Chamber Stratified Charge Combustion System developed on a Ricardo E6/Mk6 single cylinder, variable compression, spark ignition research engine in the Thermodynamics Laboratory of the Mechanical Engineering Department at the University of Canterbury. Operating a spark ignition engine on an overall lean charge has tile potential to simultaneously reduce exhaust emissions and maintain good thermal efficiency. However, problems associated with ignition of the lean mixture to increased exhaust emissions and reduced thermal efficiency. Stratified charge engines offer the potential to overcome these ignition problems, and restore thermal efficiency and reduce exhaust emissions. The stratified charge combustion process developed was centred around the separate injection of methane and air into a pre-chamber, located in an auxiliary spark plug hole in the cylinder head, to form an easily ignitable mixture which would establish a flame which would propagate through a lean mixture located in the main combustion chamber. Timing and duration of the injected methane was controlled electronically, whereas the air introduced into the pre-chamber was controlled by a metering valve and a check valve connected to the pre-chamber. The main charge to the engine was formed by using a gas carburettor.

An integrated aerodynamic-ramp-injector/plasma-torch-igniter of original design was tested in a Mâ = 2, unvitiated, heated flow facility arranged as a diverging duct scramjet combustor. The facility operated at a total temperature of 1000 K and total pressure of 330 kPa. Hydrogen (H2), ethylene (C2H4) and methane (CH4) were used as fuels, and a wide range of global equivalence ratios were tested. The main data obtained were wall static pressure measurements, and the presence of combustion was determined based on the pressure rises obtained. Supersonic and dual-mode combustion were achieved with hydrogen and ethylene fuel, whereas very limited heat release was obtained with the methane. Global operability limits were determined to be 0.07 < Ï < 0.31 for hydrogen, and 0.14 < Ï < 0.48 for ethylene. The hydrogen fuel data for the aeroramp/torch system was compared to data from a physical 10º unswept compression ramp injector and similar performance was found with the two arrangements. With hydrogen and ethylene as fuels and the aeroramp/plasma-torch system, the effect of varying the air total temperature was investigated. Supersonic combustion was achieved with temperatures as low as 530K and 680K for the two fuels, respectively. These temperatures are facility/operational limits, not combustion limits. The pressure profiles were analyzed using the Ramjet Propulsion Analysis (RJPA) code. Results indicate that both supersonic and dual-mode ramjet combustion were achieved. Combustion efficiencies varied with Ï from a high of about 75% to a low of about 45% at the highest Ï . With a theoretical diffuser and nozzle assumed for the configuration and engine, thrust was computed for each fuel. Fuel specific impulse was on average 3000 and 1000 seconds for hydrogen and ethylene respectively, and air specific impulse varied from a low of about 9 sec to a high of about 24 sec (for both fuels) for the To = 1000K test condition. The GASP RANS code was used to numerically simulate the injection and mixing process of the fuels. The results of this study were very useful in determining the suitability of the selected plasma torch locations. Further, this tool can be used to determine whether combustion is theoretically possible or not.
Ph. D.

This thesis explores the idea of igniting LPG in a compression ignition diesel engine using pilot diesel injection as spark ignition medium. The main advancement in using this technology on current diesel engines is the establishment of a better balance between NOx and PM emissions without losing too much of the CO2 benefits of diesel. With the advent of common rail diesel engines, it is now possible to get control of pilot diesel injection and make the LPG and diesel control systems work together. Combined diesel and LPG operation is a new subject for engine research, so the thesis moves on to consider the results from detailed engine simulation studies that explore the potential benefits of the mix. Subsequent simulations of a modern four cylinder dCi engine suggest that with closer control over the pilot diesel injection, diesel like performance can be obtained, hopefully with less emissions than currently expected from diesel only operation. A single cylinder variable compression ratio research engine was developed to explore diesel /LPG dual fuel operation. A second generation common rail injection rig was also developed for the engine and for fuel spray characterisation. Engine experiments proved the concept of using a modest charge of pilot injected diesel for igniting a larger dose of port injected LPG. The experimental work results suggest that combining diesel common rail injection technology with the state of the art LPG injection systems, it is possible to establish a better balance between NOx/ PM emissions without losing too much of the CO2 benefits from the diesel operation.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 130-134).
Direct Fuel Injection (DI) extends engine knock limits compared to Port Fuel Injection (PFI) by utilizing the in-cylinder charge cooling effect due to fuel evaporation. The use of gasoline/ethanol blends in DI is therefore especially advantageous due to the high heat of vaporization of ethanol. Additionally ethanol blends also display superior chemical resistance to auto-ignition, therefore allowing the further extension of knock limits. An engine with both DI and port fuel injection (PFI) was used to obtain knock onset limits for five gasoline/ethanol blends and different intake air temperatures. Using PFI as a baseline, the amount the intake air needed to be heated in DI to knock at the same conditions as PFI is the effective charge cooling realized and ranges from ~14°C for gasoline to ~49°C for E85. The Livengood-Wu auto-ignition integral in conjunction with the Douad-Eyzat time to auto-ignition correlation was used to predict knock onset. The preexponential factor in the correlation was varied to fit the experimental data. An "Effective Octane Number-ONEFF" is thus obtained for every blend ranging from 97 ONEFF. for gasoline to 115 ONEFF. for E85. ONEFF. captures the chemistry effect on knock and shows that there is little antiknock benefit beyond 30-40% ethanol by volume unless the fuel is used in a DI engine. Using this approach, the anti-knock benefit of charge cooling can also be quantified as an octane number. To achieve that, the ONEFF. calculated for an actual DI operating point including charge cooling effects is compared to the ONEFF. obtained from the auto-ignition integral if the unburned mixture temperature is offset to cancel the charge cooling out. The resulting increase in ONEFF., which can be viewed as an "Evaporative Octane Number" ranges from 5 ONEFF. for gasoline to 18 ONEFF. for E85.
by Emmanuel P. Kasseris.
Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.
Includes bibliographical references (p. 80-81).
For the purpose of researching hydrocarbon (HC) emissions in a direct-injection spark ignited (DISI) engine, five experiments were performed. These experiments clarified the role of coolant temperature, injection pressure, and injection timing in HC emissions; the final two experiments illustrated the effect of coolant temperature and injection pressure on separate sweeps of injection timing and the subsequent HC levels. The first three experiments were performed with isopentane. All five of the experiments were repeated with two fuels: UTG 91, a typical research gasoline, and a fuel with a high driveability index (DI), i.e. a less volatile fuel. The results showed less-than intuitive results for the response of HC to varying coolant temperature and varying injection pressure. For the coolant temperature data, the deviation from intuition is discussed and is probably due to vaporization problems. For the injection pressure results, the counterintuitive trend is expected to be the balance of two negative effects of high and low fuel pressure: high droplet velocities and large droplet diameters. Finally, the injection timing results were more logical. The early injections are high for this engine due to late exhaust valve closing, and the late injections have high HC because of a decreasing time to vaporize and poor mixing caused by the lack of intake air motion.
by Michael S. Radovanovic.
S.M.

A phenomenological model for a turbulent premixed flame in homogeneous turbulence, which incorporates the conservation of the probability distribution function (pdf) of a scalar, was developed. This was used to simulate the lean burn and misfire limits of combustion within a constant volume chamber. A one-dimensional numerical approximation of the pdf equation in spherical co-ordinates was obtained using the control volume formulation. The air-fuel premixture in the chamber was divided into particles of equal mass, which in turn were distributed among control volumes considered as spherical concentric shells. Monte-Carlo methods were applied to model the diffusion of particles between and mixing of particles within the concentric spherical shells. The chemical reaction of the mixture used a first order reaction from which a set of ordinary differential equations were solved for the evolution of the temperature and species concentration of each particle. Turbulence was modelled using the rapid distortion theory. A parametric study was conducted with the present model to show its operation in the misfire region of combustion. There has also been a comparison of mean expansion speeds with the compiled experimental combustion data of Bradley (1992). A suggestion for future research with the established model involves the adoption of the k-epsilon theory for the development of turbulence-related properties. This would allow comparison to the results obtained with the present rapid distortion theory for turbulence.

Increasing demands for lower carbon dioxide emissions and fuel consumption drive technological developments for car manufacturers. One trend that has shown success for reducing fuel consumption in spark ignited engines is downsizing, where the engine size is reduced to save fuel and a turbocharger is added to maintain the power output. A drawback of this concept is the slower torque response of a turbocharged engine. Recent hardware improvements have facilitated the use of variable geometry turbochargers (VGT) for spark ignited engines, which can improve the transient torque response. This thesis addresses the transient torque response through three papers. Paper 1 presents the optimal control of the valve timing and VGT for a fast torque response. Optimal open-loop control signals are found by maximizing the torque integral for a 1-d simulation model. From the optimization it is found that keeping the ratio between exhaust and intake pressure at a constant level gives a fast torque response. This can be achieved by feedback control using vgt actuation. The optimal valve timing differs very little from a fuel consumption optimal control that uses large overlap. Evaluation on an engine test bench shows improved torque response over the whole low engine speed range. In Paper 2, model based, nonlinear feedback controllers for the exhaust pressure are presented. First, the dynamic relation between requested VGT position and exhaust pressure is modeled. This model contains an estimation of the on-engine turbine flow map. Using this model, a controller based on inverting the input-output relation is designed. Simulations and measurements on the engine show that the controller handles the strong nonlinear characteristic of the system, maintaining both stability and performance over the engine’s operating range. Paper 3 considers the dependence of the valve timing for the cylinder gas exchange process and presents a torque model. A data-based modeling approach is used to find regressors, based on valve timing and pressures, that can describe the volumetric efficiency for several engine speeds. Utilizing both 1-d simulations and measurements, a model describing scavenging is found. These two models combine to give an accurate estimation of the in-cylinder lambda, which is shown to improve the torque estimation. The models are validated on torque transients, showing good agreement with the measurements.

QC 20120928

This thesis describes an investigation into the effect of piston design on hydrocarbon emissions from an spark ignited engine. The experimental investigation tested a series of three piston configurations against a standard design based on production dimensions. These tests examined the effect of top and 2nd land crevice volumes and absorption and desorption from lubricant on the cylinder liner as sources of hydrocarbon emissions. The operational conditions were steady state for all engine parameters. The work was performed on a modern four cylinder 16 valve engine with multi point fuel injection. Two fuels were used, a reference unleaded petrol and trimethyle pentane. The results have shown that significant reductions in hydrocarbon emissions can be achieved by certain design changes. Reducing the top land height from 6mm to 2.8mm reduced emissions by up to 25% and creating a smoother surface on the cylinder liner wall reduced emissions by up to 28%. A method of assessing residual lubricant on the cylinder walls was developed from surface finish measurement and showed that the smoother surface finish would retain less oil and reduce the amount of fuel absorbed by the oil. The 2nd land volume was a secondary source having an effect at low speed low load conditions. The hydrocarbon species were investigated with gas chromatography, the concentrations of these species were observed to change with each design, but not necessarily proportional to the total hydrocarbon emissions. A model was developed to allow the prediction of changes to hydrocarbon emissions by altering various piston design parameters. In addition to modelling mixture flow into piston crevice volumes and absorption of fuel by lubricant on cylinder walls a basic combustion analysis allowed the prediction of combustion gas temperatures and the end point of combustion. In-cylinder oxidation could then be approximated. Results from this model gave good agreement with experimental results and was then used to assess the optimum piston design to reduce hydrocarbon emissions. This research has demonstrated that component design and specification can be used to reduce hydrocarbon emissions from a spark ignited engine. The most significant parameters have been identified and methods of measurement developed. After considering current material and design constraints the dimensions for a low hydrocarbon emission piston was modelled and predicted 30% reduction in emissions.

Misfire occurs when operating an internal combustion engine with air fuel ratio near the lean limit. To extend the misfire limit, the combustion chamber is redesigned to promote turbulence and swirl. An experimental study has been conducted in a constant volume vessel to investigate the effects of the swirling flow, the spark location, the spark energy, the spark gap and the equivalence ratio on misfire. The relationship between spark location and misfire is investigated for the three following ignition locations: quarter radius from the wall, half radius from the wall and three quarter radius from the wall. The instantaneous velocities are measured using hot wire anemometer. Mixtures of propane and air with equivalence ratios between 0.5 and 0.64 have been tested. Misfire was determined using the pressure trace and by visually inspecting the flame through the quartz glass. The misfire probability decreases as the mean swirling velocity and turbulence intensity decay. Also the misfire probability decreases as the ignition point is nearer to the center even though the turbulence intensity is higher than that near the wall. It is postulated that the rate of growth of the flame area (flame stretching) is higher near the wall, therefore the lean misfire limit is richer.

The main scope of this project was to determine if a plasma torch could operate on pure hydrocarbon feedstocks and, if so, to catalogue the torch operational characteristics. The future goal of the project is to design a plasma torch for supersonic combustion applications that operates off of the vehicle main fuel supply to simplify onboard fuel systems. Experiments were conducted with argon, methane, ethylene and propylene. Spectrographic tests and tests designed to catalogue current/voltage characteristics, plasma jet phenomena, arc stability dependencies, electrode erosion rate and torch body temperature were performed. Spectrographic analysis of the plasma jet exhaust confirmed the presence of combustion-enhancing radicals for each hydrocarbon gas tested. Also, it was discovered that simple hydrocarbon gases, such as methane, produced smooth torch operation, while even slightly more complex gases, ethylene and propylene, caused unsteady performance. Plasma jet oscillation was found to be related to the voltage waveform of the power supplies, indicating that plasma jet length and oscillation rate could be controlled by changing the input voltage. The plasma torch for this study was proven to have the capability of operating with pure hydrocarbon feedstocks and producing radicals that are known to reduce combustion reaction rate times. The torch was demonstrated to have potential for use in supersonic combustion applications.
Master of Science

Thesis (M.S.)--University of Missouri--Rolla, 2007.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 29, 2007) Includes bibliographical references (p. 153-155).

Heavy-duty engines must meet strict emission standards and retain high fuel efficiency. This thesis examines a new type of fuel injector nozzle for a pilot-ignited direct-injection natural gas engine. The nozzle uses paired jets that increase mixing with air during combustion, which aims to reduce the amount of particulate matter (PM) formed. Tests were performed for different speeds and loads and over engine parameter sweeps (including timing, EGR, EQR, and diesel pilot mass) to compare the effects on the emissions to a single-hole nozzle. Low-PM strategies and morphology of the soot were compared as well. Contrary to expectations, the tests showed large increases in CO and PM from all the paired nozzles at all modes compared to the single-holed injector. Changing speed and load did not affect the relative emissions so further tests were only done with the paired nozzle that had the least emissions. The engine parameter sweeps at mid speed, high load (B75) showed similar emission patterns for the paired-hole nozzle and the single-hole nozzle. This suggests that the reasons for the high emissions lie in the characteristics of the jets, which are not changed much under normal HPDI operation. Injecting the natural gas before the pilot injection reduced PM. Late post-injection of some of the gas reduced PM by 50% without increasing other emissions for both injector types. Apparently, these strategies could work for other HPDI injectors. Compared to the reference injector, the paired-hole nozzle produced larger soot aggregates and larger numbers of particles but soot primary particle size showed different trends at different conditions. Soot fractal dimensions were the same and consistent with conventional diesel soot. CFD simulations showed that fuel packets moved through a richer high PM and CO forming zone during combustion for the paired nozzle. This high sooting zone had to be avoided either by further mixing or less mixing to avoid the high emissions produced. The results presented here were developed on a single-cylinder engine. While trends are expected to be similar to those from an equivalent multi-cylinder engine, emission levels and fuel consumption are not directly comparable to production multi-cylinder engines.
Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate

This diploma thesis deals with preparation of quality management system for certification according to the standard ISO/TS 16949:2009. In the theoretical part of the thesis a various concepts of quality management system are described as well as certification process of ISO/TS 16949:2009. The last theoretical chapter is dedicated to the auditing of quality management system. The practical part is focused to the analyse of the current quality management system as well as performing of internal audits of quality management system. The last chapter is focused on evaluation of effectiveness of internal audits and realization of the first phase of certification audit according to the ISO/TS 16949:2009.

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Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
In this work was used a plasma torch of non transferred arc with argon as work gas, using a power supply with maximum DC current of 250 A and voltage of 30 V to activate the plasma and keep it switched on. The flame temperature was characterized by optical emission spectroscopy, through Boltzmann-plot-method. The torch has been used like igniter in the aluminothermic reduction of the mixture tantalum oxide and aluminum, seeking to obtain metallic tantalum. In heating of the reagents only one particle will be considered to study interactions between plasma-particle, seeking to determinate its fusion and residence time. The early powders were characterized by laser granulometry, scanning electron microscopy (SEM) and X-ray diffraction analysis. The final product of this reaction was characterized by SEM and X-ray diffraction. Crystallite size was calculated by the Scherrer equation and microdeformation was determined using Willamsom-Hall graph. With Rietveld method was possible to quantify the percentile in weight of the products obtained in the aluminothermic reaction. Semi-quantitative chemical analysis (EDS) confirmed the presence of metallic tantalum and Al2O3 as products of the reduction. As was waited the particle size of the metallic tantalum produced, presents values in nanometric scale due the short cooling time of those particles during the process
Neste trabalho foi utilizada uma tocha de plasma de arco n?o transferido com arg?nio como g?s de trabalho, utilizando uma fonte de pot?ncia com corrente m?xima de 250 A e tens?o m?xima de sa?da de 30 V fornecida pelo fabricante. A temperatura da tocha foi caracterizada atrav?s da espectroscopia de emiss?o ?ptica, utilizando a curva de Boltzmann. A tocha foi usada como ignitor para a rea??o de redu??o aluminot?rmica do ?xido de t?ntalo mais alum?nio para a produ??o de t?ntalo met?lico. No aquecimento dos reagentes apenas uma part?cula ser? considerada para o estudo da intera??o tocha-part?cula, com o objetivo de determinar seu tempo de fus?o e resid?ncia. Os p?s de partida foram caracterizados atrav?s da granulometria a laser, microscopa eletr?nica de varredura (MEV) e difra??o de raios X. O produto final desta rea??o foi caracterizado por MEV e difra??o de raios X. O tamanho de cristalito foi calculado atrav?s da equa??o de Scherrer e a microdeforma??o foi determinada utilizando o gr?fico de Willamsom-Hall. Com o m?todo de Rietveld foi poss?vel quantificar o percentual em peso do produto da rea??o aluminot?rmica. An?lise qu?mica semiquantitativa (EDS) confirmou a presen?a do Ta met?lico e Al2O3 como produtos da redu??o. Como era de se esperar, o tamanho das part?culas do t?ntalo met?lico produzida apresenta valores na faixa de nan?metro devido pequeno tempo de resfriamento durante o processo

[ES] A pesar de la tendencia actual hacia la electrificación del transporte por carretera, los motores de combustión interna alternativos han sido esenciales en este sector y se espera que sigan siendo una tecnología con notable presencia durante las próximas décadas. Los vehículos de pasajeros actuales basados en motores de combustión interna son más ecológicos que los utilizados hace años, aunque todavía queda trabajo por hacer. Los sistemas de postratamiento están enfocados a minimizar tanto como sea posible el impacto de los motores de combustión interna en términos de emisiones contaminantes. En el caso de los motores de encendido provocado, los catalizadores de tres vías representan la tecnología más extendida en las últimas décadas, debido a su compacidad y buena relación precio-prestaciones. Estos convertidores son capaces de oxidar hidrocarburos y monóxido de carbono al mismo tiempo que reducen los óxidos de nitrógeno. No obstante, para lograr su mejor eficiencia, el dosado debe controlarse con precisión en torno a condiciones estequiométricas. En este sentido, los sistemas electrónicos de gestión del motor son esenciales para aprovechar las características de estos convertidores. En particular, las estrategias de control y diagnóstico desempeñan un papel clave para lograr una reducción efectiva de las emisiones en el amplio rango de condiciones de operación que se dan en condiciones de funcionamiento reales. El desarrollo de estas estrategias es fundamental, especialmente teniendo en cuenta el bajo nivel de emisiones permitido por las normativas de emisiones actuales y la tendencia hacia cero emisiones. El propósito de esta tesis doctoral es analizar el comportamiento del sistema de postratamiento en condiciones específicas pero a la vez muy comunes en conducción real, y desarrollar estrategias que proporcionen una reducción adicional de las emisiones en sistemas basados en catalizador de tres vías. Con la popularización de pequeños motores turboalimentados de encendido provocado, ha aumentado el uso de estrategias de barrido de la cámara de combustión para mitigar los típicos problemas de falta de par a bajo régimen. Esta tesis analiza el impacto de los pulsos de cortocircuito en el catalizador y en las sondas ¿. El proceso de cortocircuito de aire fresco al escape tiene un impacto importante en la dinámica intraciclo de la composición de los gases de escape. En particular, los pulsos de monóxido de carbono e hidrógeno seguidos por los pulsos de aire fresco perturban el normal funcionamiento del sensor de oxígeno. Por lo tanto, se ha propuesto un nuevo método para estimar la tasa de cortocircuito abordo. Este método permite corregir la desviación sufrida por el sensor y, por lo tanto, ayuda a reducir la penalización en emisiones de este tipo de estrategias. Para mejorar la eficiencia del catalizador en condiciones transitorias, no solo se requiere un control preciso del dosado aguas arriba del catalizador, sino que también resulta imprescindible considerar el comportamiento dinámico del convertidor en sí mismo. Por ejemplo, el almacenamiento de oxígeno es un buen indicador del estado del catalizador, pero no se puede medir directamente mediante sensores. Por lo tanto, el desarrollo de modelos es clave en las estrategias de control actuales, para poder estimar abordo diferentes parámetros relacionados con el estado del catalizador. Varios modelos de catalizador se han desarrollado en esta tesis doctoral para lidiar con diferentes cuestiones, desde la predicción de los efectos de la condensación de agua en la evolución de la temperatura del catalizador justo después del arranque en frío, a la cuantificación del nivel de envejecimiento, pasando por el control óptimo de purga del catalizador.
[CAT] Malgrat la tendència actual cap a l'electrificació del transport per carretera, els motors de combustió interna alternatius han sigut essencials en aquest sector i s'espera que continuen sent una tecnologia amb notable presència durant les pròximes dècades. Els vehicles de passatgers actuals basats en motors de combustió interna són més ecològics que els utilitzats fa anys, encara que hi ha treball per fer. Els sistemes de post-tractament estan enfocats a minimitzar tant com siga possible l'impacte dels motors de combustió interna en termes d'emissions contaminants. En el cas dels motors d'encés provocat, els catalitzadors de tres vies representen la tecnologia més estesa en les últimes dècades, pel fet que són compactes i posseeixen bona relació preu-prestacions. Aquests convertidors són capaços d'oxidar hidrocarburs i monòxid de carboni al mateix temps que redueixen els òxids de nitrogen. No obstant això, per a aconseguir la seua millor eficiència, el dosatge ha de controlar-se amb precisió entorn de condicions estequiomètriques. En aquest sentit, els sistemes electrònics de gestió del motor són essencials per a aprofitar les característiques d'aquests convertidors. En particular, les estratègies de control i diagnòstic exerceixen un paper clau per aconseguir una reducció efectiva de les emissions en l'ampli rang de condicions d'operació que es donen en condicions de funcionament reals. El desenvolupament d'aquestes estratègies és fonamental, especialment tenint en compte el baix nivell d'emissions permès per les normatives actuals i la tendència cap a zero emissions. El propòsit d'aquesta tesi doctoral és analitzar el comportament del sistema de post-tractament en condicions específiques però alhora molt comunes en conducció real, i desenvolupar estratègies que proporcionen una reducció addicional de les emissions en sistemes basats en catalitzador de tres vies. Amb la popularització de xicotets motors amb sobrealimentació d'encés provocat, ha augmentat l'ús d'estratègies de curtcircuit per a mitigar els típics problemes de falta de parell a baix règim. Aquesta tesi analitza l'impacte dels polsos de curtcircuit en el catalitzador i en les sondes ¿. El procés de curtcircuit d'aire fresc té un impacte important en la dinàmica intra-cicle de la composició dels gasos. En particular, els polsos de monòxid de carboni i hidrogen seguits pels polsos d'aire fresc pertorben el normal funcionament del sensor d'oxigen. Per tant, s'ha proposat un nou mètode per a estimar la taxa de curtcircuit del motor. Aquest mètode permet corregir la desviació patida pel sensor i, per tant, ajuda a reduir la penalització en emissions d'aquest tipus d'estratègies. Per a millorar l'eficiència del catalitzador en condicions transitòries, no solament es requereix un control precís del dosatge aigües amunt del catalitzador, sinó que també resulta imprescindible considerar el comportament dinàmic del convertidor en si mateix. Per exemple, l'emmagatzematge d'oxigen és un bon indicador de l'estat del catalitzador, però no es pot mesurar directament mitjançant sensors. Per tant, el desenvolupament de models és clau en les estratègies de control actuals, per poder estimar els diferents paràmetres relacionats amb l'estat del catalitzador. Diversos models de catalitzador s'han desenvolupat en aquesta tesi doctoral per a tractar diferents qüestions, des de la predicció dels efectes de la condensació d'aigua en l'evolució de la temperatura del catalitzador just després de l'arrencada en fred, a la quantificació del nivell d'envelliment, passant pel control òptim de porga del catalitzador.
[EN] In spite of the current tendency towards the electrification of the road transport, internal combustion engines have been essential in this sector and it is expected to continue being a technology with a noticeable presence during next decades. Current passenger cars based on internal combustion engines are greener than those used years ago, although it is still a developing process. Aftertreatment systems are aimed to minimize as much a possible the impact of internal combustion engines in terms of pollutant emissions. In case of spark-ignited engines, three-way catalytic converters represent the most widespread technology during last decades, due to their compactness and cost-performance. These converters are capable to oxidise hydrocarbons and carbon monoxide while simultaneously reducing nitrogen oxide. Nonetheless, to achieve their best efficiency, the air-to-fuel ratio must be accurately controlled close to stoichiometric conditions. In this sense, electronic engine management systems are essential to take advantage of the features of these converters. In particular, control and diagnosis strategies play a key role to achieve an effective emissions reduction under the wide range of operating conditions that arise in real driving conditions. The further development of this strategies is fundamental, especially taking into account the low emissions level allowed by current regulatory procedures and the trend towards zero emissions. The purpose of this dissertation is to analyse the behaviour of the aftertreatment system under very specific but at the same time very common conditions, and developing strategies that provide a further emissions reduction for systems based on three-way catalyst. With the popularization of small turbocharged spark-ignited engines, the use of scavenging strategies to solve the typical low-end torque issues has increased. This dissertation analyses the impact of the short-circuit pulses on both three-way catalyst and ¿ sensors. The short-circuit process has an important effect on the in-cycle dynamics of the exhaust gas composition. In particular, the carbon monoxide and hydrogen pulses followed by fresh air pulses cause a sensor bias. Thus a new method to on-line estimate the short-circuit rate has been proposed. This method allows to correct the sensor bias and, therefore, help to reduce the emissions penalty. To improve the TWC efficiency under transient conditions, not only an accurate air-to-fuel ratio control upstream of the converter is required, but also to consider the dynamic behaviour of the converter itself. For example, the oxygen storage is the main responsible for the converter dynamics, and thus, a good indicator of the catalyst state, but it cannot be directly measured. Hence the development of models is key in current control strategies, to on-line track different parameters related with the state of the converter. Several models have been derived in this dissertation in order to fulfil different requirements, from the prediction of water condensation effects on the temperature evolution inside the converter just after cold-start, to the quantification of the ageing level, through the optimal catalyst purge control, or the air-to-fuel ratio disturbances rejection.
Real Minuesa, M. (2020). Modelling, control and diagnosis of aftertreatment systems based on three-way catalyst in spark-ignited engines [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/137040
TESIS

Diesel-ignited dual-fuel (DIDF) combustion of natural gas (NG) is a promising, and immediately available strategy to improve heavy-duty compression-ignition (CI) engine performance to meet challenging and evolving emissions regulations. The DIDF concept utilizes a combination of port-injected NG and direct-injected diesel to couple the relatively low-cost and low-emissions characteristics of NG combustion with the operational and performance characteristics that have made diesel CI engines ubiquitous. This combination of fuelling strategies permits a wide range of different operating modes, which are characterized by a number of fundamental combustion mechanisms. Combustion mechanisms specific to particular modes of DIDF operation have previously been addressed, however a comprehensive conceptual description of the combustion processes and modes of DIDF operation is lacking. A clear context for specific observed phenomena and DIDF operating modes is needed to bridge and extend the conclusions of investigations in this field. That need is addressed by this investigation through experimental analysis of thermodynamic and optical measurements of a broad range of DIDF fuelling modes. A 2-litre single-cylinder CI research engine capable of both conventional and optically-accessible operation was commissioned and operated with port-injected methane (CH₄). Fuelling modes were characterized using the global equivalence ratio (φglobal =0.55—0.88) and pilot fuel ratio (Rpilot =0.06—0.61) and were performed with combinations of pilot injection timing and pressure. A novel set of criteria, which used the measured apparent heat release rate (AHRR), defined sequential stages of DIDF combustion and mapped fundamental regimes of DIDF operation in the Rpilot-φglobal space. Flame propagation, and non-flame propagation DIDF operating regimes were distinguished by an apparent lean flame propagation limit observed at a CH₄ equivalence ratio (φCH₄) equal to 0.4. Pilot injection parameters were observed to be critical to combustion and emissions processes across all operating modes except for a unique subset of operating points with Rpilot=0.06. Spatially-resolved broadband visible light and OH*-chemiluminescence measurements supported the identified operating regimes, and indicated that the conventional conceptual model of DIDF combustion is not a complete description of the DIDF combustion process for all operating modes.
Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate

A zero dimensional single zone model was developed to determine the crank resoled heat release rate at various injection timings (15°-60° BTDC) and the associated uncertainties from a pilot ignited natural gas engine. The uncertainty analysis examines the percentage contribution from various sources of error, including cylinder pressure measurements, intake manifold pressure measurements, and the impact of assumptions such as constant versus temperature dependent specific heat ratios. In particular, uncertainty percentage contributions and uncertainty magnification factors were used to quantify and compare the uncertainties in heat release rates using temperature dependent specific heat ratio correlations to constant specific heat ratio assumption. It is demonstrated that the error associated with the constant specific heat ratio assumption contributes to about 40 percent error (full scale value) in the net heat release estimates in comparison to using temperature dependent specific heat ratio correlations.