Download or read book Effect of Molecular Structure on Soot Formation Characteristics of Aviation Turbine Fuels written by Omer L. Gulder and published by . This book was released on 1988 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Molecular Structure on Soot Formation Characteristics of Aviation Turbine Fuels written by and published by . This book was released on 1988 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fuel Molecular Structure and Flame Temperature Effects on Soot Formation in Gas Turbine Combustors written by and published by . This book was released on 1989 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Fuel Molecular Structure on Soot Formation in Gas Turbine Engines written by D. W. Naegeli and published by . This book was released on 1980 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Fuel Specification and Additives on Soot Formation written by G. S. Samuelsen and published by . This book was released on 1983 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this program was to develop an employ the method necessary to identify the causal effects of fuel properties, additive properties, and combustor operating conditions on soot formation and to provide information needed to evaluate and develop models destined for gas turbine design. Present knowledge of these effects is limited to systems which are either too simple to adequately represent gas turbine combustion or too complex to permit access to detailed optical diagnostics. The projected use by Air Force aircraft of relax-detailed optical diagnostics. The projected use by Air Force aircraft of relaxed specification fuels having an increased tendency to produce soot portends greater difficulty meeting the future USAF aircraft smoke emission goals and makes this information essential. To answer these technical questions, a multifaceted study was undertaken to test candidate model laboratory combustors in the conduct of fuel effects measurement of local soot size and number density, develop and assess the effect of extractive probe perturbation to local values of soot size and number density, employ an extractive probe and sampling system to assess the effect of fuel molecular structure and additives on the physical and chemical properties of soot, and determine the effectiveness of the ASTM smoke point in predicting sooting behavior in complex flows.

Download or read book Effects of Fuel Molecular Structure on Emissions in a Jet Flame and a Model Gas Turbine Combustor written by Anandkumar Makwana and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Stricter environmental requirements, worldwide air traffic growth, and unsteady fuel prices all has led to an increased interest in alternative jet fuels. Additionally, several nations are investing resources identifying local fuel sources to make the fuel supply more resilient against disruptions and flexible to use of multiple, reliable fuel stocks. The alternative jet fuels that are being defined have unusual molecular distributions relative to current fuels. These differences in molecular structure affect the gas-phase kinetics during combustion, and hence the use of alternative fuels can impact emissions differently than conventional fuels. The differences in the emission characteristics between a newly developed alternative fuel and conventional fuel highlight the need to focus the research efforts on understanding how the fundamental properties of the fuel can affect emissions. The current work focuses on investigating the chemical effects of fuel molecular structure on the emission behavior of the fuels. In particular, the study explores how the fuel composition and premixing affect the production of polycyclic aromatic hydrocarbons (PAH), hazardous air pollutants (HAPs), and soot in a combustion environment. The study uses two experimental configurations: a jet flame and a model gas turbine combustor. Laser induced incandescence (LII) and laser extinction (LE) are used to obtain two-dimensional soot volume fraction in the flames. Laser induced fluorescence (LIF) is used to obtain the two-dimensional aromatic species distribution in the flames. Additionally, numerical analysis is used to investigate the effects of premixing on the soot formation processes in the jet flames for a high molecular weight fuel.

Download or read book Fuel Component Effects on Combuster Soot Formation written by and published by . This book was released on 1990 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The principal objective of this program was to obtain information on the effect of fuel composition and combustor operating conditions on soot formation in a model laboratory combustor which is representative of aircraft gas turbine engines (GTEs). Work included the development of a laboratory scale combustor that reflects the characteristics of practical GTEs and the blending of a fuel surrogate from pure hydrocarbons to stimulate JP-4. The results show that the soot yield is affected by fuel molecular structure, loading, engine aerodynamics, and pattern of fuel injection. The performance of the combustor was shown to be highly sensitive to the atomizing air conditions of the fuel nozzle.

Download or read book Effects of Fuel Molecular Structure and Composition on Soot Formation in Direct injection Spray Flames written by Kenth Ingemar Svensson and published by . This book was released on 2005 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Extinction and two-color soot measurement results were compared. The two-color KL values were seen to level off at around 0.5, but continue to increase monotonically as soot increased. The broad band method is therefore not good for absolute soot measurements. Natural luminosity measurements were sensitive to the first appearance of soot, but were non-linear.

Download or read book Experimental and Numerical Studies for Soot Formation in Laminar Coflow Diffusion Flames of Jet A 1 and Synthetic Jet Fuels written by Meghdad Saffaripour and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soot Formation in Laminar Diffusion Flames written by eO L. Geulder and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fuel Structure and Pressure Effects on the Formation of Soot Particles in Diffusion Flames written by Robert J. Santoro and published by . This book was released on 1988 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the first year of the present grant, efforts have concentrated on examining the effects of fuel molecular structure on soot formation in diffusion flames. Studies involving alkane, alkene, alkyne and aromatic fuel species have been studied with specific attention given to the surface growth process. Analysis of these studies has demonstrated a strong fuel structure dependence for the amount of soot formed, the conversion percentage of fuel carbon to soot, and the soot particle surface area present in these diffusion flames. However, when surface area taken into account, similar specific surface growth rate coefficients are observed for all the fuels studied. These results point to a similar surface growth process for all the fuels. Consistent with premixed flame results, the present studies show a continual decrease in this specific surface growth rate coefficient with time. Other effects of fuel structure observed include an acceleration of the inception of soot particles to lower locations and, thus, earlier times in the flame as soot conversion percentage increases. These results also point to the importance of the initial particle inception process which appears to control subsequent soot particle evolution. Keywords: Soot formation; Soot particles; Diffusion flames.

Download or read book Soot Nanostructure Evolution from Gas Turbine Engine Premixed and Diffusion Flame written by Chung-hsuan Huang and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Combustion generated soot impacts human health and climate. Particulate emissions from combustors on jet aircraft are relevant to each area, occurring at ground level and at altitude. One of the advantages of alternative fuels is their potential for reducing emission levels. Comparative field-testing of alternative fuels for their emissions was conducted in the Alternative Aviation Fuel Experiment II (AAFEX II), a NASA-led ground-based field campaign. In this study, particulate emissions from a CFM-56-2C1 engine aboard a DC-9 aircraft were characterized by HRTEM and XPS for nanostructure, carbon speciation and surface chemistry. Fuels studied included JP-8, a 50:50 (JP-8 & HRJ) blend, Hydrotreated Renewable Jet (HRJ), and a Fischer-Tropsch (FT) synthetic fuel. Soot nanostructure and surface chemistry are examined across engine power levels from 4% to 100%. Nanostructure ranged from amorphous (reflecting organic carbon) to graphitic (reflecting elemental carbon) as characterized by lamellae length analysis. With JP-8 fuel, soot particle bonding chemistry, as inferred from the XPS ratio for sp2/sp3 carbon is compared to soot nanostructure evolution. Increasing lamellae length is found to strongly correlate with increasing sp2/sp3 ratio with increasing engine power -- suggesting a change in species identity contributing to the soot growth process. Comparisons between fuels for the same power levels yielded insights into differences in soot processes as dependent upon initial fuel. Soots from the renewable HRJ and FT fuels exhibit significant nanostructure at each power level, rather than the progression as observed for JP-8. This difference is associated with differences in the soot formation environments as dependent upon fuel. To further examine the correlation between chemical environment and soot structure as manifested on different physical length scales, primary particle size versus lamellae length was compared. For JP-8 and its blend with HRJ, there is correlation with engine power, i.e. each spatial metric increases with increasing power, suggesting common underlying cause(s) for both observations. For the HRJ and FT fuels, there is no discernable trend. These results are interpreted in terms of the aromatic content of the JP-8 and blended fuels and their different pyrolysis kinetics compared to paraffinic components of the fuels. Observations of fullerenic nanostructure, particularly evident in soots from the pure paraffinic fuels were interpreted as reflecting partial premixing in order to produce the C5 membered rings for lamellae curvature. This led to the hypothesis defining this study: Partially premixed combustion produces soot with fullerenic nanostructure. Curvature is that one special feature of nanostructure that can be related back to particular gas phase specie(s), namely cyclopentadiene and PAHs containing 5-membered rings.This hypothesis was tested in the following two laboratory flame studies. Partial premixing within simple gas jet diffusion flames has a very long history -- stemming back to the Bunsen flame. Yet HRTEM data of soot from such flames appears absent. In the first study cyclopentane was used as fuel to test lamellae curvature dependence upon C5 species. Modest curvature was observed -- given competing fuel pyrolysis and ring dehydrogenation to yield cyclopentadiene, referred to as C5. Using benzene as the primary fuel with partial premixing tested the chemical path for C5 production -- proceeding through partial benzene oxidation yielding the phenoxy radical followed by CO loss to produce C5. A strong variation of lamellae curvature with oxygen content in the primary fuel stream was observed -- reflecting the increasing C5 production rate. Generality of the nanostructure dependence upon partial premixing and associated change in gas phase chemistry (compared to pure thermal pyrolysis) was demonstrated using an ordinary laboratory Bunsen burner with ethylene as fuel. In absence of partial premixing, soot production is well described by the HACA mechanism, C6 PAHs with observed flat lamellae, without curvature, dissimilar to observations here accompanying partial premixing.In the third study, the main goal was to test two main parameters -- adiabatic flame temperature (2000K) and fuel/air equivalence ratio ([phi] = 2.0) -- for their relative impact on soot nanostructure formation. The soots were collected from a burner-stabilized flat flame burning the petroleum-based JP-8, synthetic FT, and surrogate -- iso-Octane/n-Dodecane, m-Xylene/n-Dodecane, and n-Dodecane -- fuels on a McKenna burner. Images from high-resolution transmission microscopy (HRTEM) show that for the same equivalence ratio of [phi] = 2.0 with temperature maintained constant, soot from the FT fuel has significant curvature compared to soot from the JP-8 fuel, as also found in FT-derived soot from the jet engine. This comparative observation indicates two major findings. First is that the soot nanostructure depends upon initial fuel composition -- and by extension molecular structure. Similar findings from diesel engine studies have also been documented by Yehliu (2010) 1. Second is that fuel pyrolysis pathways and products also depend upon the fuel components. Adjustment of flame adiabatic temperature suggests a temperature threshold for realization of such differences. Soot nanostructure comparisons with a surrogate fuel mixture of n-dodecane/m-xylene (75:25 wt.%) further illustrate pyrolysis processes and intermediates as dependent upon fuel molecular structure and components present. To further compare the experimental results, CHEMKIN with the SERDP mechanism using the burner-stabilized flame model was carried out and processed for the three surrogate fuels, iso-Octane, n-Dodecane, and m-Xylene at various reaction temperatures and fuel/air equivalence ratios. Both the C5H5/C6H6 ratio and C3H3 profiles were distinctly different between the pure n-dodecane and m-xylene/n-dodecane mixture. That the C3H3 profile is also the main difference between the iso-octane and surrogate fuel mix suggests that C3H3 participation in 5-membered ring formation is also key to introduction of 2-D curvature in lamella -- especially given that the highest curvature is observed for FT fuel soot. Moreover, by these results the higher C5H5 observed for the surrogate mixture is an inferred consequence of the different C3H3 profile. Presently these calculated values are only used to interpret the observed curvature differences, as threshold values or the concentration dependency of curvature upon particular species are currently unknown.The goal of this study was to build a bridge between molecular gas phase species and the soot nanostructure. Initial observations of nanostructure curvature in jet engine soot prompted interest. Current chemical kinetic models can address fuel breakdown, thermal and oxidatively assisted, PAH formation and growth all via detailed kinetics, followed by soot inception via their physical and chemical coalescence. Thereafter soot models are particle based and use measured growth rates and aerosol dynamics to account for increasing soot mass and aggregate formation. No modeling studies have yet addressed the link between gas phase species with any aspect of soot nanostructure. As shown here soot nanostructure can reflect its origin, specifically the species forming the soot lamellae. The novelty of two-dimensional curvature is that it can be related uniquely to C5 species, via known chemical pathways -- involving oxygen directly or indirectly. The oxygen concentration in the primary fuel stream defines the level of partial premixing. Therein lies the origin of the hypothesis that partial premixing leads to (recognizable) curvature in soot lamellae. Definition of the operative range of [phi] and temperature will constitute future work for C5 production and its manifestation as curvature in nanostructure.

Download or read book Paper written by and published by . This book was released on 1989 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Correlation of Soot Formation in Turbojet Engines and in Laboratory Flames written by Robert K. Gould and published by . This book was released on 1981 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Data obtained from aviation gas turbine combustor tests have been examined to determine the effects of fuel properties on soot-related measurements such as engine smoke number, combustor flame radiation, and/or combustor linear temperature. Some tests of smaller laboratory combustors used to simulate these large combustors were also examined. From the existing data it is clear that soot production is a strong function of the fuel chemical composition. Variations in the physical properties of the fuel do not correlate well with soot-related effects. In studies in which a broad range of fuel properties was examined, correlation of soot-related effects with basic fuel compositional parameters including (1) the hydrogen content of the fuel, (2) the aromatic content of the fuel, and (3) the amount of multiple-ring aromatics in the fuel show that typically only the first of these correlates well. However, it has also been shown that fuel compositions can be chosen for which this correlating parameter fails.

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1989 with total page 682 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Fuel Properties on Soot Formation in Turbine Combustion written by D. W. Naegeli and published by . This book was released on 1978 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: