Omid Samimi Abianeh | Wayne State University (original) (raw)

Papers by Omid Samimi Abianeh

Volume 2: Emissions Control Systems; Instrumentation, Controls, and Hybrids; Numerical Simulation; Engine Design and Mechanical Development, 2015

Turbulent spray combustion of n-dodecane fuel was studied numerically in current paper. The ignit... more Turbulent spray combustion of n-dodecane fuel was studied numerically in current paper. The ignition delay, lift-off length, combustion chamber pressure rise, fuel penetration and vapor mass fraction were compared with experimental data. n-Dodecane kinetic model was studied by using a recently developed mechanism. The combustion chamber pressure rise was modeled and compared with experiments; the result was corrected for speed-of-sound to find the ignition delay timing in comparison with pressure-based ignition delay measurement. Species time histories and reaction paths at low and high temperature combustion are modeled and studied at two conditions, 900 K and 1200 K combustion chamber temperatures. The modeled species mass histories were discussed to define the firststage and total ignition delay timings. Among all of the studied species in this work, including OH, Hydroperoxyalkyl mass history can be utilized to determine the exact timing of luminosity-based ignition delay. Moreover, n-dodecane vapor penetration can be used to determine the luminosity-based ignition delay.

International Journal of Automotive Technology, 2014

A new coalescence model for droplets with different mixture composition is developed and implemen... more A new coalescence model for droplets with different mixture composition is developed and implemented in spray calculations. This model is based on an extension of Brazier-Smith et al. 's model (1972) for two colliding droplets with different densities. Based on the rotational kinetic and surface energies of a system of two droplets, coalescence efficiency for two colliding droplets with different densities is formulated. In the case of grazing collision, the effect of density of droplets is also included. The new droplet coalescence model is examined for evaporating and non-evaporating diesel sprays. Validation studies were carried out for both cases and the results were compared with available experimental data. The model shows good predictive capability and was demonstrated to improve the accuracy of multi-phase flow simulations.

50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2012

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D, 2011

ABSTRACT A new approach to account for simultaneously finite thermal conductivity, finite mass di... more ABSTRACT A new approach to account for simultaneously finite thermal conductivity, finite mass diffusivity and turbulence effects within atomizing liquid sprays is presented in this paper. The main contribution of this paper is to incorporate the liquid turbulence effect in modeling the multi-component droplet liquid jet evaporation. For this study, we consider a binary mixture of heptane and decane liquid fuel injected into a hot gas environment. The finite conductivity model is based on a newly developed two-temperature two-layer film theory of Chen et al. [1], where the turbulence characteristics of the droplet are used to estimate the effective thermal conductivity. Fuel droplets inherit turbulence from high Reynolds number issuing liquid injector flows. The present paper extends the formulation of Chen et al. [1] to estimate effective mass transfer diffusivity within the drop. In this model four regions are considered, interior and the surface of the droplet, the liquid gas interface and the surrounding gas phase. An approximate solution to the quasi-steady energy equation was used to derive an explicit expression for the heat flux from the surrounding gas to the droplet–gas interface, with inter-diffusion of fuel vapor and the surrounding gas taken into account. The thermo-transport properties including their dependence on temperature are considered. Validation studies were carried out by comparison with the experimental results.

ASME 2011 Internal Combustion Engine Division Fall Technical Conference, 2011

ABSTRACT A new approach to account for finite thermal conductivity, finite mass diffusivity and t... more ABSTRACT A new approach to account for finite thermal conductivity, finite mass diffusivity and turbulence effects within atomizing liquid sprays at high pressure condition is presented in this paper. The finite conductivity model is based on a newly developed two-layer film theory, where the turbulence characteristics of the droplet are used to estimate the effective thermal conductivity [1]. The present paper extends the formulation to model the multi-component mass diffusivities within the droplet phase at high pressures but less than components critical pressures. An approximate solution to the quasi-steady energy equation was used to derive an explicit expression for the heat flux from the surrounding gas to the droplet–gas interface, with inter-diffusion of fuel vapor and the surrounding gas taken into account. The Peng-Robinson equation of state (EOS) is used for extension of the model to the high pressures. The latent heat of vaporization and fuel enthalpies are also corrected for high pressure. The model includes the non-ideal gas and liquid behavior, and variable thermo-transport properties including their dependence on pressure and temperature. For this study a mixture of decane and hexadecane fuel droplet was considered. Predictions of the high-pressure single droplet model are in good agreement with the available data in literature.

Combustion and Flame, 2015

Gasoline direct-injection spark-ignition engines and gasoline direct-injection compression-igniti... more Gasoline direct-injection spark-ignition engines and gasoline direct-injection compression-ignition engines have received attention due to their higher fuel economy with respect to conventional port fuel injected internal combustion spark-ignition engines. Combustion modeling of these types of engines requires a fuel surrogate that mimics both physical (e.g., evaporation) and chemical (e.g., combustion) characteristics of the gasoline fuel. In this work, we propose a novel methodology for the formulation of a gasoline surrogate based on the essential physical and chemical properties of the target gasoline fuel. Using the proposed procedure, a surrogate with seven components has been identified to emulate the physical and chemical characteristics of a real non-oxygenated gasoline fuel, RD387. A surrogate kinetic mechanism was developed by combining available detailed kinetic mechanisms from the Lawrence Livermore National Laboratory library. The modeling results for distillation curve, ignition delay and laminar flame speed were validated against available experimental data in the literature. The surrogate and gasoline fuels display similar physical/chemical properties, including distillation curve, H/C ratio, density, heating value, and ignition behavior and flame propagation over a wide range of pressures, temperatures, and equivalence ratios. (O.S. Abianeh). distillation curves and evaporation behaviors of these components and their mixtures are different from gasoline as discussed later. On the other hand, suggested representatives for modeling gasoline distillation or evaporation behavior are n-pentane, n-heptane, and n-decane (e.g., ). However, mixtures of these components cannot emulate the ignition delays and laminar flame speeds of gasoline adequately. The question of the present work is: can a single mixture be formulated that will mimic both the evaporation and combustion characteristics of the target gasoline? Towards that goal, a surrogate that includes most of the hydrocarbon group representatives found in a non-oxygenated gasoline is developed here to emulate the combustion and evaporation behaviors of this target gasoline. The surrogate contains n-alkane, iso-alkane, aromatic, and olefin representatives and a detailed kinetic mechanism is built from literature mechanisms for each of the species. The surrogate components and mixture composition are defined via a methodology that seeks a surrogate formulated from a minimum number of species that have relatively well defined kinetic mechanisms and provides adequate emulation of real gasoline evaporation and ignition behaviors.

Gas motion within the cylinder is one of the major factors that control the combustion process in... more Gas motion within the cylinder is one of the major factors that control the combustion process in spark ignition engine. It also has significant impact on heat transfer. Both the bulk gas motion and the turbulence characteristics of the flow are important and governing the overall behavior of the flow. An arrangement for obtaining a stratified charge, using port injection, is proposed for a current design of a spark ignition engine. The behavior of combustion are simulated with Computational fluid dynamic and tested. Engine testing was performed using dynamometer for measuring the lean burn limit of the current spark ignition engine. Some concepts for premixed lean burn are introduced during the previous decade and with this state of the art concept the swirl and tumble flow pattern can generate in each speed, therefore the effect of these pattern on lean burn limit is investigated.

Advanced Computational Methods and Experiments in Heat Transfer XII, 2012

ABSTRACT A multicomponent evaporation and dissolution model was applied to study the dynamics of ... more ABSTRACT A multicomponent evaporation and dissolution model was applied to study the dynamics of the mass transfer of dispersed oil in shallow waters. This model, in Lagrangian form, was coupled with the Princeton Ocean Circulation model (POM) for simulating oil droplet dispersion in an oceanic environment. The oil dispersion was modeled for a standard sea-mount shallow water environment. The most abundant petroleum hydrocarbons in the hydrocarbon-enriched of oil plum larger than C1-C5 were benzene, toluene, ethylbenzene, and total xylenes. Therefore, the oil surrogate, which consists of these components, is studied. The liquid–liquid equilibrium and vapor–liquid equilibrium equations are solved for evaluating the droplet life time. A rapid mixing model is used by reason of the shorter internal mass diffusion time scale in comparison to the droplet life time. Four different droplet sizes, 1.5, 1, 0.5, and 0.1mm, are considered in this study. The droplet with a diameter of 1mm has a shorter life time in this specific environment. Keywords: multicomponent oil droplet dispersion, evaporation, dissolution, ocean circulation model, Rapid mixing model. 1 Introduction Multicomponent liquid droplet size history during evaporation and dissolution influences the dynamic behavior of the droplets, whereas the variation of the composition determines the distribution of the fuel compounds within the environment, and also the droplet life time. The fundamental understanding of

International Journal of Automotive Technology, 2009

Environmental improvement and energy issues are increasingly becoming more important as worldwide... more Environmental improvement and energy issues are increasingly becoming more important as worldwide concerns. Natural gas is a good alternative fuel that can help to improve these issues because of its large quantity and clean burning characteristics. This paper provides the experimental performance results of a Bi-Fuel engine that uses Compressed Natural Gas as its Primary fuel and gasoline as its secondary fuel. This engine is a modification of the basic 1.4-liter gasoline engine. Generally, on the unmodified base engine, torque and power for CNG fuel are considerably lower than gasoline fuel. In this paper, the influence of fuels on wall temperature, performance and emissions are investigated.

International Journal of Heat and Mass Transfer, 2014

The overarching goal of this study is to implement computationally effective models that can pred... more The overarching goal of this study is to implement computationally effective models that can predict the evaporation of multi-component fuel droplets/spray using a multidimensional Computational Fluid Dynamics (CFD) code. The new approach for modeling heat and mass transfer inside a droplet accounts for finite thermal conductivity, finite mass diffusivity, and turbulence effects within the atomizing liquid droplet/spray for multi-component fuel droplet evaporation. This model was developed and validated against experimental measurements for single droplet vaporization and one-way evaporating sprays previously, and is implemented into CFD code for two-way coupled numerical modeling study in this research. A new coalescence model for droplets with different mixture composition was also implemented into CFD code in this research. Thereby, the evaporation of multi-component diesel fuel surrogate spray in hot gas environment was predicted and compared with available experimental measurements. The model shows good predictive capability and was demonstrated to improve the accuracy of multiphase flow simulations.

International Journal of Heat and Mass Transfer, 2012

A new approach to simultaneously account for finite thermal conductivity, finite mass diffusivity... more A new approach to simultaneously account for finite thermal conductivity, finite mass diffusivity and turbulence effects within atomizing multicomponent liquid fuel sprays has been developed in this study. The main contribution of this paper is to incorporate the liquid turbulence effect in modeling the boundary layer heat and mass resistance during multi-component droplet evaporation. The finite conductivity model is based on an existing two-layer film theory, where the turbulence characteristics of the droplet are used to estimate the effective thermal conductivity. The present paper extends the two-layer film theory formulation to include multi-component mass diffusivities within the droplet liquid phase. In this model four regions are considered: the interior region of the droplet, droplet-side interface, gas-side interface, and the surrounding gas phase. Approximate solutions to the quasi-steady energy and mass transfer equations were used to derive an explicit expression for the heat and mass flux from the surrounding gas to the droplet-gas interface, and within the multi-component droplet. Extension of the model to high pressures using the Peng-Robinson equation of state is also considered. The validation study was carried out for a bi-component decane/hexadecane fuel, followed by application studies of complex gasoline-ethanol blended fuels evaporating in hot gas environments.

International Journal of Chemical Reactor Engineering, 2000

A theoretical/computational approach has been developed to satisfy mass transfer rates and molar ... more A theoretical/computational approach has been developed to satisfy mass transfer rates and molar fraction constraints simultaneously when modeling mass transfer from a finite source towards an infinite surrounding media. The procedure is based on using a mass balance of individual molecular species coupled with individual mass transfer rates. Since the surrounding media is assumed insoluble in the finite media, the total number of moles transferred across the interface is computed on the basis of modified molar fractions of the transferring species. Two simple examples are shown: the first is an evaporating droplet in air and the second example is a droplet being dissolved in water. These examples have very large differences in time scales and illustrate the versatility and accuracy of the computational procedure.

Industrial & Engineering Chemistry Research, 2012

There are two basic theoretical and computational problems associated with batch distillation. Th... more There are two basic theoretical and computational problems associated with batch distillation. The forward or direct problem consists on generating the distillation curve of a given mixture. This is an old problem, but new results are presented here to relate mathematical properties of the distillation curve with the physicochemical properties of the molecular species present in the mixture. The inverse problem consists of, given a distillation curve, finding a surrogate mixture that would accurately represent experimental data. There is more than one solution to the reverse problem because there are theoretically an infinite number of mixtures that will present very similar experimental distillation curves. The method developed in this paper requires the same number of molecular species in the surrogate mixture as the points of the distillation curve that will be matched precisely. The choice of exact points to match on the distillation curve allows to conform a square system of equations where the number of equations is equal to the number of unknowns. Other points of the distillation curve are satisfied within a prescribed small error tolerance. A surrogate mixture for gasoline was developed as an example.

A study of turbulent spray combustion of n-dodecane was conducted using computational fluid dynam... more A study of turbulent spray combustion of n-dodecane was conducted using computational fluid dynamics simulations. We report a new skeletal mechanism based on the reduction of a detailed kinetic reaction mechanism for high pressure conditions (50-60 bar), temperatures from 750 to 2500 K, and a range of equivalence ratios from 0.5 to 1.5. The skeletal mechanism has 85 species and 266 reactions. The mechanism was implemented in a computational fluid dynamic code to model the combustion of n-dodecane in a high pressure (60 bar) and temperature (900 K) constant volume chamber. A dynamic structure turbulence model with fine mesh size was utilized. Both first-stage low-temperature combustion, or cool-flame, and second-stage high-temperature combustion were observed due to the decrease in the gas temperature surrounding the spray caused by the fuel evaporative cooling. The species mass fraction histories were studied numerically to find a correlation between first-stage and second-stage combustion and species consumption. Species mass fractions, combustion chamber pressure, and combusting n-dodecane vapor penetration histories were studied computationally, and the results were compared with experiments to find a numerical equivalent to the light-based activated OH chemiluminescence ignition delay experiment.