Sharif Digital Repository

In this paper, we would like to know how to synthesize soot in a paraffin-oil flame. To do this, we use an in-house developed numerical code and simulate the soot formation in a turbulent paraffin-oil flame. However, it is necessary to evaluate first this code to ensure its reliable prediction of the soot formation and thermal behavior of the flame. So, we simulate a benchmark turbulent paraffin-oil flame and compare our obtained results against the available experimental data. The comparison insinuates the capability of current numerical code in correct predictions of both flame structure and pollution species. Then, a glass slide is installed inside the combustor. This disk-shaped glass... 

In this paper, we would like to know how to synthesize soot in a paraffin-oil flame. To do this, we use an in-house developed numerical code and simulate the soot formation in a turbulent paraffin-oil flame. However, it is necessary to evaluate first this code to ensure its reliable prediction of the soot formation and thermal behavior of the flame. So, we simulate a benchmark turbulent paraffin-oil flame and compare our obtained results against the available experimental data. The comparison insinuates the capability of current numerical code in correct predictions of both flame structure and pollution species. Then, a glass slide is installed inside the combustor. This disk-shaped glass... 

The main objective of this work is to investigate the effects of using a miniature or mini-scale air-distributor on the formation of soot nano-particles in a gas turbine combustor burning the jet propellant JP. To evaluate the achieved numerical predictions, it is necessary to choose a test case with available experimental data. It helps to compare the predicted flame structure with that of measurement. After the validation step, the chosen combustor configuration is modified to an inverse non-premixed flame configuration. This helps to split the incoming air between the primary and secondary air streams and to inject the primary air into the inverse flame via a primary air injector.... 

This paper is concentrated on soot formation in a JP combustor and it studies the emission in its exhaust gases when the combustor is equipped with different types of exhaust swirler. So, to approve the developed solver, it is required to predict one related flame structure accurately right at the first step. In this regard, we solve a well-documented benchmark test case with available data from experiment. These data are then compared with the current numerical results to evaluate the discrepancies. The comparison indicates that there is good agreement between them. Afterwards, we equip a similar combustor with different types of swirler, simulate the new designed combustor configurations,... 

This paper is concentrated on soot formation in a JP combustor and it studies the emission in its exhaust gases when the combustor is equipped with different types of exhaust swirler. So, to approve the developed solver, it is required to predict one related flame structure accurately right at the first step. In this regard, we solve a well-documented benchmark test case with available data from experiment. These data are then compared with the current numerical results to evaluate the discrepancies. The comparison indicates that there is good agreement between them. Afterwards, we equip a similar combustor with different types of swirler, simulate the new designed combustor configurations,... 

As is known, jet propulsion fuels are rather complex with combustion resulting in a vast range of chemical compounds. So, their real modeling is rather hard and the application of final constructed models is restricted to a narrow band of real propulsion jet fuels. The main objective of this study is to extend suitable surrogate fuel models to reliably predict the combustion and soot characteristics of the equivalent jet propulsion fuel. In this regard, the combustion of proposed surrogate fuels is numerically studied in the above chosen combustion chamber. Of importance, the surrogate fuels should be proposed suitably to represent the correct physical characteristics and the real chemical... 

This study examines different soot sub-models to simulate the soot nano-aerosol formation in turbulent kerosene-surrogate flames. The examinations are carried out at three different elevated pressures. We use a two-equation soot model considering the aerosol dynamics and chemistry of soot nano-particles, i.e. nucleation, coagulation, surface growth, and oxidation. Four different soot sub-models are used to predict the structures of pressurized flames. These structures are then compared with each other as well as the data collected by experiment. Our findings indicate that the acetylene soot-inception sub-model performs poorly in prediction of the flames’ structures at different elevated... 

In the absence of powerful rigorous models, in this research a simple but practical method for calculating the temperature and residence time and carbon black yield in oil-furnace reactors is proposed. For this purpose an empirical formula of the form CXHY is assumed for the carbon black feedstock based on typical feedstock used in this industry. Based on the prevailing reactor conditions, thermodynamic considerations and available outlet tail gas from the reactor, a few representative reactions are considered to describe the entire reaction network. These include complete combustion for the fuel and, incomplete combustion and pyrolysis for the feedstock. Carbon black yield can be estimated... 

In this study, a jet propulsion JP combustor is studied numerically to investigate the combustor wall temperature influences on the soot characteristics emitted at its exhaust. There are a number of ways to control the combustor wall temperatures benefiting from different wall cooling technologies. Irrespective of using different high technology cooling systems, it is important to recognize how the wall temperature can affect the soot emission from one specific JP engine. Before examining the main combustor, it is important to assess the accuracy of the computational fluids dynamics (CFD) tool via solving a benchmark problem. In this regard, the predicted flame structure for the benchmark... 

This work numerically studies the effects of inlet air and fuel turbulators on the thermal behavior of a combustor burning the jet propulsion (JP) (kerosene-surrogate) fuel and its resulting pollutants emission including the nanoparticulate soot aerosols and aromatic compounds. To model the soot formation, the method employs a semi-empirical two-equation model, in which the transport equations for soot mass fraction and soot number density are solved considering soot nanoparticles evolutionary process. The soot nucleation is described using the phenyl route in which the soot is formed from the polycyclic aromatic hydrocarbons. Incorporating a detailed chemical mechanism described by 200... 

In this study an expression for soot absorption coefficient is introduced to extend the weighted-sum-of-gray gases data to the furnace medium containing gas-soot mixture in a utility boiler 150 MWe. Heat transfer and temperature distribution of walls and within the furnace space are predicted by zone method technique. Analyses have been done considering both cases of presence and absence of soot particles at 100% load. To validate the proposed soot absorption coefficient, the expression is coupled with the Taylor and Foster's data as well as Truelove's data for CO2-H2O mixture and the total emissivities are calculated and compared with the Truelove's parameters for 3-term and 4-term gray... 

A gaseous-kerosene/air turbulent nonpremixed flame in a combustion chamber is simulated to investigate the effects of fuel-injector cone-angle on the pollutions of soot nano-particles, carbon monoxide, and carbon dioxide. We use a two-equation soot model in our studying, consider a detailed chemical scheme consisting of 121 species and 2613 elementary reactions, use the flamelet model, employ the presumed-shape probability density functions PDFs, apply the two-equation κ-ε turbulence model with round-jet corrections, and take into account the radiation effects assuming optically-thin flame in our numerical modeling. This research concentrates on investigating the impacts of kerosene injector... 

Feeding a laboratory furnace with the gaseous kerosene, the resulting two-phase turbulent flame is simulated to study the effects of injecting soot nano-particles into the inflow air on the emissions of smoke aerosol, CO, and CO2species pollutants, and the resulting radiation heat transfer. We use our past experiences in aerosol modeling of soot nano/micro particles in turbulent nonpremixed flames burning simple hydrocarbon fuels and extend them to study the effects of injecting gaseous kerosene on the aforementioned parameters. To model the evolutionary process of soot nanoparticle formation, i.e., the nucleation, coagulation, surface growth, and oxidation, we employ a two-equation soot... 

In this paper, the effects of a baffle plate on flame deflection and its throttling are investigated numerically in a combustor consuming jet propellant JP. We study the plate effects on the resulting soot volume fraction, soot particles diameter, mass fractions of carbon monoxide (CO), carbon dioxide (CO2), and benzene (C6H6). We use a two-equation turbulence model, a PAH-inception two-equation soot model imposing oxidation due to OH agents, a detailed chemical kinetic consisting of 121 species and 2613 elementary reactions, and the flamelet combustion model to perform the current study. We also take into account the turbulence-chemistry interaction using the presumed-shape probability...