Salah Ibrahim

Loughborough University (UK) in 2005, Aero and Auto engineering, Faculty Member

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Daniel S. Brogan

Virginia Western Community College

SAURABH GUPTA

NIT RAIPUR

Tapan Sengupta

IIT Kanpur

Umesh Unnikrishnan

Georgia Institute of Technology

Danielle Moreau

The University of New South Wales

Con Doolan

University of Adelaide

Joseph Majdalani

Auburn University

Mikail F Lumentut

National Taiwan University

KANNAN B T

SRM UNIVERSITY

Mohammad Shojafar

University of Surrey

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Papers by Salah Ibrahim

A new experimental technique for the study of turbulent premixed flames

Symposium (International) on Combustion, 1998

Turbulence effects on chemical reactions in smog chamber flows

Atmospheric Environment (1967), 1987

ABSTRACT Turbulent mixing effects on the reaction rate of a non-premixed flow are presented for a... more ABSTRACT Turbulent mixing effects on the reaction rate of a non-premixed flow are presented for a moderately slow second-order irreversible chemical reaction. The turbulent mixing process leads to inhomogeneities in the concentration of the reactants. Chemical reactions are normally highly non-linear and large errors can result from using average concentrations in the computation of mean reaction rates. A brief review of the literature on this problem and its application areas is made with particular emphasis placed on near isothermal flows where the fluctuation in the reaction rate constant can be neglected. The reaction between mixing air jets containing dilute nitric oxide, NO, and ozone, O3, is studied in a large Turbulent Smog Chamber (TSC) under conditions of high Reynolds number, three-dimensional flow. The measured reactant concentrations, obtained with good time and space resolution, are used to investigate the effects of the reactant species concentration fluctuations on the mean reactant species concentration field through their contribution to the mean reaction rate. Two flow geometries have been studied: two opposed jets issuing into a large chamber and a plume-like source issuing into a turbulent background flow. A three-dimensional finite-difference computation has been carried out for the flow in the chamber using the k-ε-g model of turbulence and mixing. The reacting species concentration field is calculated by considering the transport of a ‘perturbation variable’ equal to the mean of the difference between the species concentration and its corresponding fast chemistry value. A closure for the mean chemical reaction rate based on this quantity is presented and its experimental validation discussed.

A Numerical Study on the Effects of Gas Channel Wettability in PEM Fuel Cells

ECS Transactions, 2014

ABSTRACT The wettability of channel walls and gas diffusion layer has a great influence on the wa... more ABSTRACT The wettability of channel walls and gas diffusion layer has a great influence on the water management of fuel cells. In this paper, a numerical study has been carried out to examine the effect of the wall and gas diffusion layer wettability on gas channels. The investigation employed a three dimensional numerical simulation using the volume-of-fluid (VOF) method to simulate the air-water flow in a straight micro-channel representing a gas channel in a PEM fuel cell. Nine combinations of wall and GDL wettabilities were investigated. Different wettability combinations were found to give different water behaviour. For fixed wall wettability, the pattern of the analysed parameters was changing between uniform cyclic, random cyclic and continuous. In addition, it was found that changing the GDL wettability has a greater impact on the analysed parameter compared to changing the wall wettability.

A numerical study of the effects of IEGR on the set-off auto-ignition in an HCCI engine

The shortcomings of traditional combustion techniques are being continually evaluated and alterna... more The shortcomings of traditional combustion techniques are being continually evaluated and alternate combustion modes are being sought. One such combustion mode that is receiving a lot of attention is Homogenous Charge Compression Ignition (HCCI). HCCI is a combustion process that has the potential to be highly efficient and produces low emissions. It can provide high, diesel-like efficiencies using gasoline, diesel, and most alternative fuels. The major drawback with HCCI is controlling the ignition timing over a wide range of load and speed. The local chemical and thermal conditions of the charge mixture, towards the end of the compression stroke, have significant influences on the set-off auto-ignition. In this paper, numerical study has been carried out to examine the effects of mixture quality on the occurrence of auto-ignition at the end of the compression stroke inside a pentroof combustion chamber. The effect of different Internal Exhaust Gas Re-circulation (IEGR) are investigated. The use of IEGR acts as an indirect control method, the rate of combustion can be slowed down; however the percentage of IEGR retained in the cylinder affects the onset of auto-ignition. The calculated results have been validated against published experimental data, so that the correlation between the two can be discussed. It is found that the inhomogeneity of the air, fuel and the IEGR mixing, presented here in terms of temperature distribution, plays an important role in initiating, and potentially further controlling the HCCI combustion. During the compression process, certain parts of the engine charge are found to reach a higher temperature which auto-ignited depending on the percentages of IEGR used.

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Experimental analysis of in-cylinder flow structure using PIV

Numerical investigation of a spark ignition engine turbulent flow

Numerical calculations have been carried out to investigate the transient flow structure inside a... more Numerical calculations have been carried out to investigate the transient flow structure inside a four valves, 1.8L Lotus cylinder at an engine speed of 1500rpm. A dynamic mesh CFD simulation has been conducted to represent the real movement of the piston and valves. The main advantage of the dynamic mesh modelling is that it provides the time history of individual flow realisations. Calculations included the inlet port and moving valves so that the flow field can be analysed in detail. The eddy viscosity k-ε RNG turbulence model was used throughout this study. The predicted results were validated against experimental LDA measurements. respectively. The volume compression ratio is 10.5. The engine bore is 80.5mm, the stroke is 88.2mm with a connecting rod length of 131mm. In this paper, results are presented and discussed for the variation of turbulence parameters such as turbulence intensity, kinetic energy and its dissipation rate during the intake and compression strokes at various crank-angle positions. The calculation results are in good agreement with the LDA measurements. Moreover, the results have revealed the formation of a strong tumble flow motion during the inlet stroke as well as the creation of a clockwise vortex at the bottom of the cylinder. Nomenclature ε = turbulent dissipation rate (TDR) K = turbulence kinetic energy (TKE)  = density  = dynamic viscosity

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Validation of in-cylinder flow of a controlled auto-ignition engine

CALCULATION OF MIXING AND CHEMICAL-REACTION IN A TURBULENT SMOG CHAMBER

Twenty-Sixth Symposium (International) on Combustion

Validation of in-cylinder flow structure of controlled auto-ignition engine

Numerical calculations have been carried out to investigate the in-cylinder transient flow struct... more Numerical calculations have been carried out to investigate the in-cylinder transient flow structure of a controlled auto-ignition (CAI) engine running at speeds of 1,500rpm and 2000rpm. The calculated turbulent flow structure and velocities are validated against published laser Doppler anemometry (LDA) experimental data (Pitcher et al., 2003). The experimental data was reprocessed to represent the time dependent mean velocities for all measured points. The actual geometry configuration of the engine is imported into the computational fluid dynamics (CFD) code used in this study. The simulations take into account the movement of the inlet, exhaust valves and the piston. The CFD simulations replicate the experimental work where only air was inserted into a driven optical engine. Also, to simulate an engine in controlled auto-ignition (CAI) mode, the same valve timing that allows 36% internal exhaust gas recirculation (IEGR) was applied for the air intake. The calculated results found...

Calculations of in-cylinder flow of a controlled auto-ignition (CAI) engine

After validation of the numerical model against published laser doppler anemometry (LDA) experime... more After validation of the numerical model against published laser doppler anemometry (LDA) experimental data (Pitcher et al., 2003), numerical calculations have been carried out to investigate the in-cylinder transient flow structure of a controlled auto-ignition (CAI) engine running at speeds of 1,500 rpm and 2,000 rpm. The geometry configuration of the engine is imported into the computational fluid dynamics (CFD) code used in this study. The simulations take into account the movement of the inlet, exhaust valves and the piston. To simulate an engine in controlled autoignition (CAI) mode, the same valve timing that allows 36% gas residuals was applied to the model. The evolution of the flow pattern inside the cylinder at the symmetrical cross section is described. Also, the turbulence intensity (TI), the turbulent kinetic energy (TKE) and turbulent dissipation rate (TDR) are described for a better understanding of the effect of engine speed on the turbulences generated. The effects ...

Uses of o -Hydroxybenzoylacetone in the Synthesis of Some Substituted 2-Methylchromones, Chelating Agents, and Related Materials

Industrial & Engineering Chemistry Research, 2001

The nitration of o-hydroxybenzoylacetone (1) gave either the unexpected 2, 3-benzofurandione 2-ox... more

Geometry Effects on Premixed Turbulent Propagating Flames

Dynamics of Deflagrations and Reactive Systems: Flames, 1991

Geometry Effects on Premixed Turbulent Propagating Flames SS Ibrahim,* RS Cant,* and KNC Bray* Un... more

Numerical Simulation of Liquid Water Behavior in Microchannel With a 90° Bend

ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology, 2013

ABSTRACT Water management is an effective way of improving Proton Exchange Membrane (PEM) fuel ce... more ABSTRACT Water management is an effective way of improving Proton Exchange Membrane (PEM) fuel cell performance and durability. Changing the wettability of gas channel walls and gas diffusion layer (GDL) is one way of controlling the water management in a fuel cell for its influence on the liquid water dynamic behavior. The objective of this study is to investigate liquid water dynamic behavior in a microchannel with a 90° bend and different surface wettability combinations through 3D numerical simulation. Volume-of-fluid (VOF) method was employed to track the fluid-fluid interface in the multiphase flow.The simulated microchannel has a square cross-section with a dimension of 0.25 mm and a total length of 1.5 mm. Water is introduced to the channel via two pores in the bottom surface representing a GDL while air flows from one end to another. The air and water velocities used are in the order of magnitude of a high current density fuel cell. Nine different combinations of wall/GDL wettability are investigated.The results show that liquid water takes less time to leave the channel in a hydrophilic GDL compared to moderate and hydrophobic GDL regardless of wall wettability. Furthermore, the GDL wettability shows more significant impact on liquid water behavior compared to the wall wettability; however, wall wettability has a slight but considerable impact.

Numerical Analysis of Flow Structure inside a Single Cylinder of a 4 Valve Head under Steady-State Condition

SAE Technical Paper Series, 2013

In-Cylinder Flow Structure Analysis by Particle Image Velocimetry Under Steady State Condition

SAE Technical Paper Series, 2012

Wrinkling Scales of Turbulent Premixed Propagating Flame Fronts Obtained From LIF-OH Imaging

Fourth …, 2005

A key outstanding issue with turbulent premixed flames lies in modeling the burning rate which ma... more

Large eddy simulation of a turbulent nonpremixed piloted methane jet flame (Sandia Flame D)

Proceedings of the Combustion Institute, 2005

Large eddy simulation (LES) is conducted of the Sandia Flame D [Proc. Combust. Inst. 27 (1998) 10... more Large eddy simulation (LES) is conducted of the Sandia Flame D [Proc. Combust. Inst. 27 (1998) 1087, Sandia National Laboratories (2004], which is a turbulent piloted nonpremixed methane jet flame. The subgrid scale (SGS) closure is based on the scalar filtered mass density function (SFMDF) methodology [J. Fluid Mech. 401 (1999) 85]. The SFMDF is basically the mass weighted probability density function (PDF) of the SGS scalar quantities [Turbulent Flows (2000)]. For this flame (which exhibits little local extinction), a simple flamelet model is used to relate the instantaneous composition to the mixture fraction. The modelled SFMDF transport equation is solved by a hybrid finite-difference/Monte Carlo scheme. This is the first LES of a realistic turbulent flame using the transported PDF method as the SGS closure. The results via this method capture important features of the flame as observed experimentally.

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Turbulent premixed flame propagation in a cylindrical vessel

Symposium (International) on Combustion, 1996

ABSTRACT

Rationalization of the up-grading circuit of celestite for advanced applications

Powder Technology, 2010

The conversion of celestite into other strontium compounds, mainly strontium carbonate, is a nece... more The conversion of celestite into other strontium compounds, mainly strontium carbonate, is a necessary step for many industrial applications. However, the impurities need to be removed to achieve a suitable celestite grade (N 90% SrSO 4 ) for the conversion process. Therefore, this paper is aimed at celestite separation from calcite using gravity separation (i.e., jig and shaking table). The jig was used to deal with coarse sizes (− 15 + 2.0 mm) while shaking table was used to deal with finer sizes (− 0.5 + 0.080 mm) or cleaning the jig tailings after further regrinding to − 0.5 mm. Moreover, the shaking table separation was evaluated in terms of its operating parameters using statistical design of experiments. Starting from the primary crushed − 0.5 + 0.080 mm fraction contains 44.91% SrO (79.58% SrSO 4 ), a celestite concentrate 51.88%SrO (91.93% SrSO 4 ) was produced at optimum conditions; i.e., 25%, 3 cm, 25 l/min, and 6 degree for pulp density, stroke length, water flow rate, and table slope, respectively.

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A new experimental technique for the study of turbulent premixed flames

Symposium (International) on Combustion, 1998

Turbulence effects on chemical reactions in smog chamber flows

Atmospheric Environment (1967), 1987

A Numerical Study on the Effects of Gas Channel Wettability in PEM Fuel Cells

ECS Transactions, 2014

A numerical study of the effects of IEGR on the set-off auto-ignition in an HCCI engine

Download

Experimental analysis of in-cylinder flow structure using PIV

Numerical investigation of a spark ignition engine turbulent flow

Download

Validation of in-cylinder flow of a controlled auto-ignition engine

CALCULATION OF MIXING AND CHEMICAL-REACTION IN A TURBULENT SMOG CHAMBER

Twenty-Sixth Symposium (International) on Combustion

Validation of in-cylinder flow structure of controlled auto-ignition engine

Calculations of in-cylinder flow of a controlled auto-ignition (CAI) engine

Uses of o -Hydroxybenzoylacetone in the Synthesis of Some Substituted 2-Methylchromones, Chelating Agents, and Related Materials

Industrial & Engineering Chemistry Research, 2001

The nitration of o-hydroxybenzoylacetone (1) gave either the unexpected 2, 3-benzofurandione 2-ox... more

Geometry Effects on Premixed Turbulent Propagating Flames

Dynamics of Deflagrations and Reactive Systems: Flames, 1991

Geometry Effects on Premixed Turbulent Propagating Flames SS Ibrahim,* RS Cant,* and KNC Bray* Un... more

Numerical Simulation of Liquid Water Behavior in Microchannel With a 90° Bend

ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology, 2013

Numerical Analysis of Flow Structure inside a Single Cylinder of a 4 Valve Head under Steady-State Condition

SAE Technical Paper Series, 2013

In-Cylinder Flow Structure Analysis by Particle Image Velocimetry Under Steady State Condition

SAE Technical Paper Series, 2012

Wrinkling Scales of Turbulent Premixed Propagating Flame Fronts Obtained From LIF-OH Imaging

Fourth …, 2005

A key outstanding issue with turbulent premixed flames lies in modeling the burning rate which ma... more

Large eddy simulation of a turbulent nonpremixed piloted methane jet flame (Sandia Flame D)

Proceedings of the Combustion Institute, 2005

Download

Turbulent premixed flame propagation in a cylindrical vessel

Symposium (International) on Combustion, 1996

ABSTRACT

Rationalization of the up-grading circuit of celestite for advanced applications

Powder Technology, 2010

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