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Intelligent Control via Wireless Sensor Networks for Advanced Coal Combustion Systems

Description: Numerical Modeling of Solid Gas Flow, System Identification for purposes of modeling and control, and Wireless Sensor and Actor Network design were pursued as part of this project. Time series input-output data was obtained from NETL's Morgantown CFB facility courtesy of Dr. Lawrence Shadle. It was run through a nonlinear kernel estimator and nonparametric models were obtained for the system. Linear and first-order nonlinear kernels were then utilized to obtain a state-space description of the … more
Date: August 5, 2007
Creator: Behal, Aman; Kumar, Sunil & Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Developing Supersonic Impactor and Aerodynamic Lens for Separation and Handling of Nano-Sized Particles

Description: A computational model for supersonic flows of compressible gases in an aerodynamic lens with several lenses and in a supersonic/hypersonic impactor was developed. Airflow conditions in the aerodynamic lens were analyzed and contour plots for variation of Mach number, velocity magnitude and pressure field in the lens were evaluated. The nano and micro-particle trajectories in the lens and their focusing and transmission efficiencies were evaluated. The computational model was then applied to des… more
Date: June 30, 2008
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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University/NETL Student Partnership Program

Description: The University/National Energy Technology Laboratory (NETL) Student Partnership Program stimulated basic and applied research in Energy and Environmental Science areas through NETL's Office of Science and Technology (OST). This Partnership Program supported the education of graduate students in Energy and Environmental Sciences, while fostering increased scientific interaction between NETL and the participating universities, by providing graduate student support for research at a NETL facility … more
Date: October 31, 2006
Creator: Holder, Gerald; Mathews, Jonathan; Wilson, Thomas; Chuang, Steven; Amon, Cristina; Ertekin, Turgay et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Measurement of Interfacial Area Production and Permeability within Porous Media

Description: An understanding of the pore-level interactions that affect multi-phase flow in porous media is important in many subsurface engineering applications, including enhanced oil recovery, remediation of dense non-aqueous liquid contaminated sites, and geologic CO2 sequestration. Standard models of two-phase flow in porous media have been shown to have several shortcomings, which might partially be overcome using a recently developed model based on thermodynamic principles that includes interfacial … more
Date: January 1, 2010
Creator: Crandall, Dustin; Ahmadi, Goodarz & Smith, Duane H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Distribution and occurence of localized-bursts in two-phase flow through porous media

Description: This study examines the dynamics of two-phase drainage with experiments of air invasion into a translucent water-saturated porous medium, at low injection speeds. Air displaces the water by irregular bursts of motion, suddenly invading small portions of the medium. These periods of activity, followed by dormancy, are similar to descriptions of systems at a self-organized critical point, where a slight disturbance may induce an avalanche of activity. The fractal characteristics of the invading a… more
Date: January 1, 2008
Creator: Crandall, Dustin; Ahmadi, Goodarz; Ferer, Martin & Smith, Duane H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Fundamentals of Natural Gas and Species Flows from Hydrate Dissociation - Applications to Safety and Sea Floor Instability

Description: Semi-analytical computational models for natural gas flow in hydrate reservoirs were developed and the effects of variations in porosity and permeability on pressure and temperature profiles and the movement of a dissociation front were studied. Experimental data for variations of gas pressure and temperature during propane hydrate formation and dissociation for crushed ice and mixture of crushed ice and glass beads under laboratory environment were obtained. A thermodynamically consistent mode… more
Date: September 30, 2006
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Couette flows of a granular monolayer: An experimental study

Description: An experimental study concerning rapid flows of granular materials in a two dimensional planar granular Couette flow apparatus is performed. The device is capable of generating particulate flows in grain-inertia regime at different shearing rates and solid volume fractions. Multi-color spherical glass particles are sheared across an annular test-section for several wall angular velocities. A video recorder is used to record the motion of particles, and consecutive images are stored and analyzed… more
Date: March 1995
Creator: Elliott, Kenneth E.; Ahmadi, Goodarz & Kvasnak, William
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A thermodynamical formulation for chemically active multi-phase turbulent flows

Description: A generalized thermodynamics for chemically active multiphase solid-fluid mixtures in turbulent state of motion is formulated. The global equations of balance for each phase are ensemble averaged and the local conservation laws for the mean motions are derived. The averaged and the local conservation laws for the mean motions are derived. The averaged form of the Clausius-Duhem inequality is used and the thermodynamics of the chemically active mixtures in turbulent motion is studied. Particular… more
Date: March 1995
Creator: Ahmadi, Goodarz & Cao, Jianfa
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Direct, Dynamic Measurement of Interfacial Area within Porous Media

Description: Standard models of two-phase flow in porous media have been shown to exhibit several shortcomings that might be partially overcome with a recently developed model based on thermodynamic principles (Hassanizadeh and Gray, 1990). This alternative two-phase flow model contains a set of new and non-standard parameters, including specific interfacial area. By incorporating interfacial area production, destruction, and propagation into functional relationships that describe the capillary pressure and… more
Date: January 1, 2010
Creator: Crandall, Dustin; Ahmadi, Goodarz; Smith, Duane H. & Bromhal, Grant
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Experimentally Measured Interfacial Area during Gas Injection into Saturated Porous Media: An Air Sparging Analogy

Description: The amount of interfacial area (awn) between air and subsurface liquids during air-sparging can limit the rate of site remediation. Lateral movement within porous media could be encountered during air-sparging operations when air moves along the bottom of a low-permeability lens. This study was conducted to directly measure the amount of awn between air and water flowing within a bench-scale porous flow cell during the lateral movement of air along the upper edge of the cell during air injectio… more
Date: January 1, 2010
Creator: Crandall, Dustin; Ahmadi, Goodarz & Smith, Duane H., Bromhal, Grant
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Two-Phase Flow Simulations In a Natural Rock Fracture using the VOF Method

Description: Standard models of two-phase flow in porous media have been shown to exhibit several shortcomings that might be partially overcome with a recently developed model based on thermodynamic principles (Hassanizadeh and Gray, 1990). This alternative two-phase flow model contains a set of new and non-standard parameters, including specific interfacial area. By incorporating interfacial area production, destruction, and propagation into functional relationships that describe the capillary pressure and… more
Date: January 1, 2010
Creator: Crandall, Dustin; Ahmadi, Goodarz & Smith, Duane H., Bromhal, Grant
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Fundamentals of Natural Gas and Species Flows from Hydrate Dissociation-Applications to Safety and Sea Floor Instability

Description: Natural gas production from the dissociation of methane hydrate in a confined reservoir by a depressurizing down-hole well was studied. The case that the well pressure was kept constant was treated and two different linearization schemes in an axisymmetric configuration were used in the analysis. For different fixed well pressures and reservoir temperatures, approximate self-similar solutions were obtained. Distributions of temperature, pressure and gas velocity field across the reservoir were … more
Date: September 1, 2005
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Ash & Pulverized Coal Deposition in Combustors & Gasifiers

Description: Further progress in achieving the objectives of the project was made in the period of October 1 to December 31, 1996. In particular, the sublayer model for evaluating the particle deposition in turbulent flows was extended to include the effect of particle rebound. A new more advance flow model for the near wall vortices is also used in these analysis. The computational model for simulating particle transport in turbulent flows was used to analyze the dispersion and deposition of particles in a… more
Date: December 2, 1998
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Ash & Pulverized Coal Deposition in Combustors & Gasifiers

Description: Further progress in achieving the objectives of the project was made in the period of October I to December 31, 1997. The direct numerical simulation of particle removal process in turbulent gas flows was continued. Variations of vorticity contours which are averaged over a short time duration are studied. It is shown that the near wall vortices profoundly affect the particle removal process in turbulent boundary layer flows. The sublayer model for evaluating the particle deposition in turbulen… more
Date: December 2, 1998
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Ash & Pulverized Coal Deposition in Combustors & Gasifiers

Description: Further progress in achieving the objectives of the project was made in the period of January I to March 31, 1998. The direct numerical simulation of particle removal process in turbulent gas flows was completed. Variations of particle trajectories are studied. It is shown that the near wall vortices profoundly affect the particle removal process in turbulent boundary layer flows. Experimental data for transport and deposition of fibrous particles in the aerosol wind tunnel was obtained. The me… more
Date: December 2, 1998
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Ash & Pulverized Coal Deposition in Combustors & Gasifiers

Description: Further progress in achieving the objectives of the project was made in the period of July 1 to September 30, 1997. The direct numerical simulation of particle removal process in turbulent gas flows was continued. Variations of vorticity contours which are averaged over a short time duration are studied. It is shown that the near wall vortices profoundly affect the particle removal process in turbulent boundary layer flows. The sublayer model for evaluating the particle deposition in turbulent … more
Date: December 2, 1998
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A computational model for coal transport and combustion

Description: In the period of December 1, 1991 to February 28, 1992 further progress has been made in formulation of the thermodynamically consistent rate dependent model for turbulent two-phase flows. The thermodynamically admissible constitutive equations were derived, and the case of a simple shear flow was also studied. A stress transport model for rapid granular flows in a rotating frame of reference was formulated. The thermodynamically consistent constitutive equations were derived. It was shown that… more
Date: Spring 1992
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A computational model for coal transport and combustion

Description: During the last three months, considerable progress has been made in formulation of the thermodynamically consistent rate dependent model for turbulent two-phase flows. The basic governing equations were derived and the case of a simple shear flow was also analyzed. Preliminary comparisons with the available experimental data were also performed. The thermodynamical approach was successfully formulated for developing a stress transport model for granular flows. The appropriate constitutive equa… more
Date: Winter 1991
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A computational model for coal transport and combustion. Quarterly technical progress report, March 1, 1992--May 31, 1992

Description: In the period of March 1, 1992 to May 30, 1992 considerable progress has been made in the development of the stress transport model for rapid granular flows in a rotating frame of reference. The derivation of thermodynamically consistent constitutive equations were complete. It was shown that the model contains the existing kinetics theories as special limiting cases. The model predictions for the special case of rapid simple shear flows were evaluated and the results are compared with the simu… more
Date: June 2, 1992
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A computational model for coal transport and combustion

Description: In the period of March 1, 1992 to May 30, 1992 considerable progress has been made in the development of the stress transport model for rapid granular flows in a rotating frame of reference. The derivation of thermodynamically consistent constitutive equations were complete. It was shown that the model contains the existing kinetics theories as special limiting cases. The model predictions for the special case of rapid simple shear flows were evaluated and the results are compared with the simu… more
Date: June 2, 1992
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A computational model for coal transport and combustion

Description: The thermodynamically consistent, rate dependent model for turbulent two-phase flows was used to study the special case of a simple shear. The variations of the fluctuation kinetic energy with the solid volume fraction was evaluated. The kinetic model for rapid flows of granular materials, which includes frictional losses, was used for studying gravity flow down an inclined chute. The velocity profiles were obtained and the results were compared with the data of Johnson et al. The effect of dia… more
Date: Winter 1992
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A computational model for coal transport and combustion

Description: Further progress has been made in formulation of the thermodynamically consistent, rate dependent model for turbulent two-phase flows. The thermodynamically admissible constitutive equations were derived, and the case of a simple shear flow was studied. The kinetic model for rapid flows of granular materials, which includes frictional losses, was used for studying gravity flow down an inclined chute. Some typical velocity profiles were obtained and the results were compared with the data of Sav… more
Date: Autumn 1992
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A Computational Model for Coal Transport and Combustion. Quarterly Technical Progress Report, September 1, 1993--November 30, 1993

Description: In the period of September 1, 1993 to November 30, 1993, further progress was made of the theoretical and computational modeling of turbulent two-phase flows, as well as granular flows. The effect of bumpy wall on flow of granular materials was also analyzed. The special case of Couette flow was studied. Further progress was made in the experimental study of mono-layer simple shear flow device. Preliminary data concerning the sharing of 12 mm multi-color glass particles are obtained. The prelim… more
Date: Winter 1993
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A computational model for coal transport and combustion. Quarterly technical progress report, June 1, 1992--August 31, 1992

Description: Further progress has been made in formulation of the thermodynamically consistent, rate dependent model for turbulent two-phase flows. The thermodynamically admissible constitutive equations were derived, and the case of a simple shear flow was studied. The kinetic model for rapid flows of granular materials, which includes frictional losses, was used for studying gravity flow down an inclined chute. Some typical velocity profiles were obtained and the results were compared with the data of Sav… more
Date: October 1992
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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