Author: Mohammad Reza KholghyPublisher:
ISBN: 9780494919699
Category :
Languages : en
Pages :
Book Description
The Evolution of Soot Morphology in Laminar Co-Flow Diffusion Flames of the Surrogates for Jet A-1 and a Synthetic Kerosene
Author: Mohammad Reza KholghyPublisher:
ISBN: 9780494919699
Category :
Languages : en
Pages :
Book Description
Experimental and Numerical Studies for Soot Formation in Laminar Coflow Diffusion Flames of Jet A-1 and Synthetic Jet Fuels
Author: Meghdad SaffaripourSoot Morphology in a Laminar Co-flow Diffusion Flame
Author: Jidong XiaoDetailed Modeling of Soot Formation/Oxidation in Laminar Coflow Diffusion Flames
Author: Detailed Modeling of Soot Formation/oxidation in Laminar Coflow Diffusion Flames
Author: Qingan ZhangPublisher:
ISBN: 9780494609002
Category :
Languages : en
Pages : 388
Book Description
The first goal of this thesis is to develop and validate a modeling tool into which fundamental combustion chemistry and aerosol dynamics theory are implemented for investigating soot formation/oxidation in multi-dimensional laminar coflow diffusion flames taking into account soot polydispersity and fractal-like aggregate structure. The second goal is to use the tool to study soot aggregate formation/oxidation in experimentally studied laminar coflow diffusion flames to advance the understanding of soot aggregate formation/oxidation mechanism.The first part of the thesis deals with the large CPU time problem when detailed models are coupled together. Using the domain decomposition method, a high performance parallel flame code is successfully developed. An advanced sectional aerosol dynamics model which can model fractal-like aggregate structure is successfully implemented into the parallel flame code. The performance of the parallel code is demonstrated through its application to the modeling of soot formation/oxidation in a laminar coflow CH4/air diffusion flame. The parallel efficiency reaches as high as 83%.In the third part of the thesis, the effects of oxidation-driven soot aggregate fragmentation on aggregate structure and soot oxidation rate are studied. Three fragmentation models with different fragmentation patterns are developed and implemented into the sectional aerosol dynamics model. The implementation of oxidation-driven aggregate fragmentation significantly improves the prediction of soot aggregate structure in the soot oxidation region.The second part of the thesis numerically explores soot aggregate formation in a laminar coflow C2H4/air diffusion flame using detailed PAH-based combustion chemistry and a PAH-based soot formation/oxidation model. Compared to the measured data, flame temperature, axial velocity, C2 H2 and OH concentrations, soot volume fraction, the average diameter and the number density of primary particles are reasonably well predicted. However, it is very challenging to predict effectively the average degree of particle aggregation. To do so, particle-particle and fluid-particle interactions that may cause non-unitary soot coagulation efficiency need to be considered. The original coagulation model is enhanced in this thesis to accommodate soot coagulation efficiency. Different types of soot coagulation efficiency are numerically investigated. It is found that a simple adjustment of soot coagulation efficiency from 100% to 20% provides good predictions on soot aggregate structure as well as flame properties.
Effect of Flow Unsteadiness on Soot Morphology
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The morphology of combustion-generated soot is of fundamental interest, but is difficult to measure. A new planar diagnostic technique was developed for morphology measurements in simple laminar flames. Additionally, Polycyclic Aromatic Hydrocarbons, (PAH) the precursors to soot formation, were measured non-intrusively in an unsteady laminar flame to determine the characteristic time scales of their formation. An existing point-wise laser scattering technique to determine soot morphology was extended to a planar technique and applied to a laminar ethylene air co-flow flame. An Nd:YAG laser (532 nm) was used to illuminate the soot particles and the resulting scattered light was collected over a wide range of angles. A low power laser was used to eliminate fluorescence and incandescence interferences. Simultaneous laser induced incandescence measurements were used to determine the soot volume fraction. Six morphological parameters, including primary spherule size and mass fractal dimension, were derived using this new planar measurement technique based on RDG/PFA theory. The results clearly show the soot formation processes, including inception, agglomeration, and oxidization. A two-angle approximate method was also demonstrated and shown to be applicable for instantaneous measurements in unsteady flames. The approximate method can provide limited soot morphology information including primary particle size and number of primary particles per aggregate, when the fractal dimension and distribution are assumed. The approximate method was not suitable over the entire region of this flame because the fractal dimension varies significantly from the assumed value of 1.8, particularly in the soot inception zone. Three different size classes of PAH were measured qualitatively via laser induced fluorescence by detecting fluorescence in different spectral regions. The relative concentrations of these PAH were measured in counterflow diffusion flames subjected to both steady and.
Soot Formation in Laminar Jet Diffusion Flames
Author: Peter Bradford SunderlandPublisher:
ISBN:
Category :
Languages : en
Pages : 262
Book Description
Effect of Pressure on Soot Morphology in Laminar Diffusion Flames
Author: Ben GigonePublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The effect of pressure on soot aggregate morphology in laminar diffusion flames, specifically pertaining to primary soot particle size and soot aggregate fractal parameters, was investigated in methane-air and nitrogen-diluted ethylene flames. Soot aggregate samples were collected by thermophoretic sampling within a high-pressure combusting chamber. Soot samples were imaged via transmission electron microscopy followed by an automated imaging detection method. The experiments covered pressures from 7 to 30 bar at vertical flame heights of 3, 6, and 8 mm in methane-air flames, and 3 to 6 bar at heights of 2, 5, 10, and 15 mm in nitrogen-diluted ethylene flames. It was observed that mean primary soot particle size increased with increasing pressure for both fuel types at virtually all flame locations. The fractal dimension was found to vary with pressure for both fuel cases, suggesting that a universal soot aggregate fractal value may not be justified in high-pressure flames.
Soot Formation in Ethane-air Coflow Laminar Diffusion Flames at Elevated Pressures
Author: Paul Michael MandatoriPublisher:
ISBN: 9780494160565
Category : Combustion
Languages : en
Pages : 198
Book Description
Ethane-air laminar coflow non-smoking diffusion flames have been studied at pressures up to 3.34 MPa to determine the effect of pressure on soot formation, flame temperatures and physical flame properties. The spectral soot emission (SSE) diagnostic was used to obtain spatially resolved (both radially and axially) soot volume fraction and soot temperature measurements at pressures of 0.20 to 3.34 MPa. In general, temperature profiles of a given height were found to decrease with increasing pressure. Pressure was found to enhance soot formation with decreased sensitivity as pressures were increased. A power law relation between maximum soot volume fraction and pressure was found to be fvmax & prop;P 2.39 for 0.20 & le; P & le; 1.52 MPa and fvmax & prop;P 1.10 for 1.52 & le; P & le; 3.34 MPa. The integrated line-of-sight soot volume fraction was found to vary as fvline, max & prop;P 2.32 for 0.20 & le; P & le; 0.51 MPa, fvline, max & prop;P 1.44 for 0.51 & le; P & le; 1.52 MPa and fvline, max & prop;P 0.95 for 1.52 & le; P & le; 3.34 MPa. The variation of maximum carbon conversion to soot, as a percentage of the fuel's carbon, was etas, max & prop; P2.23 for 0.20 & le; P & le; 1.13 MPa, etas, max & prop; P1.12 for 0.51 & le; P & le; 1.52 MPa and etas, max & prop; P0.41 for 1.52 & le; P & le; 3.34 MPa. The maximum value of carbon conversion was found to be eta s, max = 27.61% at P = 3.34 MPa.
Author: Guozheng Lin