Particle emission characteristics of a gas turbine with a double annular combustor

The total climate, air quality and health impact of aircraft black carbon (BC) emissions depends on quantity (mass and number concentration), as well as morphology (fractal dimension and surface area) of emitted BC aggregates. This study examines multiple BC emission metrics from a gas turbine with a double annular combustor, CFM56-5B4-2P. As a part of the SAMPLE III.2 campaign, concurrent measurements of particle mobility, particle mass, particle number concentration and mass concentration, as well as collection of transmission electron microscopy (TEM) samples, allowed for characterization of the BC emissions. Mass- and number-based emission indices were strongly influenced by thrust setting during pilot combustion and ranged from <1 to 208 mg/kg-fuel and 3×1012 to 3×1016 particles/kg-fuel, respectively. Mobility measurements indicated that mean diameters ranged from 7-44 nm with a strong dependence on thrust during pilot-only combustion. Using aggregation and sintering theory with empirical effective density relationships, a power law relationship between primary particle diameter and mobility diameter is presented. Mean primary particle diameter ranged from 6-19 nm, however, laser induced incandescence (LII) and mass-mobility calculated primary particle diameters demonstrated opposite trends with thrust setting. Similarly, mass-mobility-calculated aggregate mass specific surface area and LII-measured surface area were not in agreement, indicating both methods need further development and validation before use as quantitative indicators of primary particle diameter and mass-specific surface area.The authors express their gratitude to a number of people and organizations in helping to plan, conduct, finance and provide instruments for this measurement campaign. The 537 European Aviation Safety Agency (EASA) funded the SAMPLE III SC02 campaign (EASA.2010.FC.10, Specific Contract No: SC02). The Federal Office of Civil Aviation, Switzerland (FOCA) was critical in for providing additional financial support and arranging facilities which made this study possible. We also thank the SR Technics test bed staff, including Frithjof Siegerist, for operating the engines and enabling access to the test facility. We thank AVL, Cambustion, Grimm & TSI supplying both instruments and expertise.This is the author accepted manuscript. The final version is available from Taylor & Francis via http://dx.doi.org/10.1080/02786826.2015.107845

Prediction of particle deposition in the respiratory track using 3D–1D modeling

AbstractAirflow simulation of the whole respiratory system is still unfeasible due to the geometrical complexity of the lung airways and the diversity of the length scales involved in the problem. Even the new CT imaging system is not capable of providing accurate 3D geometries for smaller tubes, and a complete 3D simulation is impeded by the limited computational resources available. The aim of this study is to develop a fully coupled 3D–1D model to make accurate prediction of airflow and particle deposition in the whole respiratory track, with reasonable computational cost and efficiency. In the new proposed method, the respiratory tree is divided into three parts to be dealt with using different models. A three dimensional model is used to compute the airflow in the upper part of the tree, while the distal part is studied using a 1D model. A lumped model is also used for the acinar region. The three models are coupled together by implementing the physical boundary conditions at the model interfaces. In the end, this multiscale model is used to find the deposition pattern of particles within a sample lung

Detection of fault lineaments of the Zagros fold-thrust belt based on Landsat imagery interpretation and their spatial relationship with Hormoz Series salt dome locations using GIS analysis

In the Zagros structural zone of Iran, there is a broad range of emergent salt domes, a unique morphology in the world that is developed in tectonic environment. In the Zagros fold-thrust belt, emergent salt domes exhibit linear patterns. Such trends appear to be related to linear structural features that are observable by Landsat imagery. Detection of fault lineaments and their spatial relationship with salt dome locations from statistics point of view have been the concerns of this study. Based on the remote sensing analyses, horizontal displacements of parts of folded structures and distribution of Hormuz series salt domes, 34 fault lineaments were detected. A statistical method called the weight of evidence method is used to determine the relationship between salt dome locations and fault lineament trends. For this purpose, a map of the fault lineaments and a map of the salt dome centers were converted to raster model and some buffers were extracted around the fault lineaments; then, the spatial relationship between the salt domes and fault lineaments were quantified using weights of evidence method. Results indicate that the salt domes are associated spatially with the fault lineaments within lateral distances of 1 km. Weights of evidence method shows that the fault lineaments related to tectonics of the region could be the most important factor in emplacement of the salt domes in the study area

Detection of fault lineaments of the Zagros fold-thrust belt based on Landsat imagery interpretation and their spatial relationship with Hormoz Series salt dome locations using GIS analysis

In the Zagros structural zone of Iran, there is a broad range of emergent salt domes, a unique morphology in the world that is developed in tectonic environment. In the Zagros fold-thrust belt, emergent salt domes exhibit linear patterns. Such trends appear to be related to linear structural features that are observable by Landsat imagery. Detection of fault lineaments and their spatial relationship with salt dome locations from statistics point of view have been the concerns of this study. Based on the remote sensing analyses, horizontal displacements of parts of folded structures and distribution of Hormuz series salt domes, 34 fault lineaments were detected. A statistical method called the weight of evidence method is used to determine the relationship between salt dome locations and fault lineament trends. For this purpose, a map of the fault lineaments and a map of the salt dome centers were converted to raster model and some buffers were extracted around the fault lineaments; then, the spatial relationship between the salt domes and fault lineaments were quantified using weights of evidence method. Results indicate that the salt domes are associated spatially with the fault lineaments within lateral distances of 1 km. Weights of evidence method shows that the fault lineaments related to tectonics of the region could be the most important factor in emplacement of the salt domes in the study area

Improved sizing of soot primary particles using mass-mobility measurements

The properties and impacts of aggregated aerosol particles (i.e., soot, metal oxide fumes) depend on their morphology, as characterized by fractal dimension, prefactor, and primary particle diameter. The morphology may be measured directly by time-consuming ex situ microscopy or rapid but indirect in situ methods. Previously, it was found that particle mass and mobility measurements could be used for the estimation of the primary particle diameter of zirconia aggregates, using plausible assumptions related to the fractal structure (specifically, prefactor kα and exponent Dα). Since the formation and growth of zirconia aggregates are different from carbon soot, here we compare primary particle diameters measured directly from transmission electron microscopy analysis of soot particles with the diameters estimated from mass-mobility measurements. Performing extensive measurements on soot emissions from two reciprocating engines over a range of operating conditions, we found that there are no universal values of kα and Dα that can be used for all conditions. However, new optimized values of kα and Dα are estimated here for soot particles. The variation of the primary particle diameter with particle size is also taken into consideration and is shown to be essential to obtain physically realistic results. Using optimized values of kα and Dα, the average primary particle sizing error is reduced for all soot types. This suggests that with some calibration, in situ sizing of the primary particle diameter, using mass and mobility measurements, can provide useful accuracy

Size, effective density, morphology, and nano-structure of soot particles generated from buoyant turbulent diffusion flames

With a global gas flaring volume of ∼140 billion cubic meters, flares are an important source of particulate emissions; however, very little is known about the physical and morphological properties of these particle emissions. To study these properties, a laboratory pipe flare producing a buoyant turbulent diffusion flame was used which allowed controlled experiments on flames up to ∼3 m tall. Three flare diameters (38.1, 50.8, and 76.2 mm) were used in this study with fuel exit velocities of 0.5, 0.9, and 1.5 m/s. ‘Light’ ‘medium’ and ‘heavy’ fuel compositions (consisting of C1 to C4 alkanes, carbon dioxide, and nitrogen in concentration representative of flares in the Alberta, Canada upstream oil and gas sector) were used, where heavier compositions refer to a greater concentration of higher order alkanes. Size distributions of soot particles were measured using a scanning mobility particle sizer. Mass-mobility relationship and effective density of particles were determined using a tandem arrangement of a differential mobility analyzer, a centrifugal particle mass analyzer and a condensation particle counter. Morphology and nano-structure of the particles were studied using transmission electron microscopy and Raman spectroscopy, respectively. Results showed that the particle median diameter and concentration increased as the fuel composition was changed from light to medium to heavy. On the other hand, particle morphology, measured by the relationships between particle mass vs. mobility (or effective density) and primary particle size vs. particle aggregate size, was independent of fuel composition, flow rate, or flare size and was in good agreement with previously reported values for that of soot particles from different internal combustion engines. Previously developed relations between effective density and primary particle size work well for the soot particles of this study. Raman spectroscopy indicated slightly lower D1/G ratios (more graphitic content) for the heavier fuels