Mohy Mansour

Design of laser cavities is a complicated process. It includes several optical, geometrical and m... more Design of laser cavities is a complicated process. It includes several optical, geometrical and material parameters. Computer Aided Design of laser cavities reduces the time and effort required to reach the optimum design. In this paper an accurate and fast three dimensional CAD model for simulating solid-state laser systems is developed. Numerical estimations of the geometrical transfer efficiency of various cavities are presented. Analytical and iterative methods to achieve a feasible converged solution for designing optimum pumping champers which contains different geometrical dimensions of laser rods, flash lamps and walls reflectivity are discussed. A simulation study of the pumping efficiency of the laser heads with respect to the cavity geometry, different geometries of laser rods and flashlamps, and reflecting coatings have been carried out. The goal is to achieve a maximum concentration of the light flux of the pumping source towards the active medium. Results are presented using Matlab and Microsoft office excel. Computer aided design is then used to create three dimensional parametric model of laser cavity assembly. The proposed model has been compared with published results and shown to be very accurate and efficient for modeling three-dimensional solid-state laser chambers.

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Laser Accelerators

It is now a fact that focusing an intense ultra short laser pulse onto a gas jet or thin targets,... more It is now a fact that focusing an intense ultra short laser pulse onto a gas jet or thin targets, generates energetic collimated electrons or ions forming ultra short beams of energies &amp;amp;gt; 100 MeV. The different mechanisms to explain such laser accelerated electrons or ions will be discussed. Data obtained by recent experiments will be presented. We report the

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Effect of Partial Premixing on Stabilization and Local Extinction of Turbulent Methane/Air Flames

Flow, turbulence and combustion, Sep 18, 2012

The stabilization characteristics and local extinction structures of partially premixed methane/a... more The stabilization characteristics and local extinction structures of partially premixed methane/air flames were studied using simultaneous OH-PLIF/PIV techniques, and large eddy simulations employing a two-scalar flamelet model. Partial premixing was made in a mixing chamber comprised of two concentric tubes, where the degree of partial premixing of fuel and air was controlled by varying the mixing length of the chamber. At the exit of the mixing chamber a cone was mounted to stabilize the flames at high turbulence intensities. The stability regime of flames was determined for different degree of partial premixing and Reynolds numbers. It was found that in general partially premixed flames at low Reynolds numbers become more stable when the level of partial premixing of air to the fuel stream decreases. At high Reynolds numbers, for the presently studied burner configuration there is an optimal partial premixing level of air to the fuel stream at which the flame is most stable. OH-PLIF images revealed that for the stable flames not very close to the blowout regime, significant local extinction holes appear already. By increasing premixing air to fuel stream successively, local extinction holes grow in size leading to eventual flame blowout. Local flame extinction was found to frequently attain to locations where locally high velocity flows impinging to the flame. The local flame extinction poses a future challenge for model simulations and the present flames provide a possible test case for such study.

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Laser science and applications : proceedings of the sixth international conference, National Institute of Laser Enhanced Sciences, Cairo University, Egypt, 15-18 January 2007

WORLD SCIENTIFIC eBooks, 2010

High-Power Lasers and Interactions (C Chatwin & R Young) Laser Accelerators (L El-Nadi) Laser... more High-Power Lasers and Interactions (C Chatwin & R Young) Laser Accelerators (L El-Nadi) Laser Manipulation of Atoms (L El-Nadi et al.) Analytical Studies of Laser Beam Propagation Through the Atmosphere (M I El-Saftawy et al.) Optical Design Alternatives: A Survey Study (A A K Ismail et al.) Materials for Digital Optical Design: A Survey Study (S H Ahmed et al.) Proposed Design for Optical Digital Circuits (A A Ismail et al.) Photo-Induced Effect on Bacterial Cells (M H El-Batanouny et al.) Molecular Mechanisms and Apoptosis in PDT (B Krammer et al.) and other papers.

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Laser-Based Techniques for Temperature and Species Measurements

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$Research paper thumbnail of Evaluation of partially premixed flame stability from mixture fraction statistics in a turbulent slot burner$

Evaluation of partially premixed flame stability from mixture fraction statistics in a turbulent slot burner

HAL (Le Centre pour la Communication Scientifique Directe), 2017

International audienc

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Structure and stability characteristics of turbulent planar flames with inhomogeneous jet in a concentric flow slot burner

Proceedings of the Combustion Institute, 2021

Turbulent flames with compositionally inhomogeneous mixtures are common in many combustion system... more Turbulent flames with compositionally inhomogeneous mixtures are common in many combustion systems. Turbulent jet flames with a circular nozzle burner were used earlier to study the impact of inhomogeneous mixtures, and these studies showed that the nozzle radius affects the flame stability. Accordingly, planar turbulent flames with inhomogeneous turbulent jet are created in a concentric flow slot burner (CFSB) to avoid this effect in the present study. The stability characteristics, the mixing field structure, and the flame front structure were measured, and the correlations between stability and the mixing field structure were investigated. The mixture fraction field was measured in non-reacting jets at the nozzle exit using highly resolved Rayleigh scattering technique, and the flame front was measured in some selected turbulent flames using high-speed Planar Laser-Induced Fluorescence (PLIF) of OH technique. The data show strong correlations between flame stability and the range of mixture fraction fluctuations. The flames are highly stabilized within a mixing field environment with the range of fluctuation in mixture fraction close to the range of the flammability limits. The mixing field structure is also illustrated and discussed using a mixing regime diagram and showed that the scatter of the data of the different cases is consistent with the classified mixing regimes. Lean flames are stabilized in the current slot burner. The flame front structure topology varies consistently

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$Research paper thumbnail of Evaluation of partially premixed turbulent flame stability from mixture fraction statistics in a slot burner$

Evaluation of partially premixed turbulent flame stability from mixture fraction statistics in a slot burner

Combustion Science and Technology, Apr 11, 2018

Partially premixed combustion is characterized by mixture fraction inhomogeneity upstream of the ... more Partially premixed combustion is characterized by mixture fraction inhomogeneity upstream of the reaction zone and occurs in many applied combustion systems. The temporal and spatial fluctuations of the mixture fraction have tremendous impact on the combustion characteristics, emission formation, and flame stability. In this study, turbulent partially premixed flames are experimentally studied in a slot burner configuration. The local temperature and gas composition is determined by means of one-dimensional, simultaneous detection of Rayleigh and Raman scattering. The statistics of the mixture fraction are utilized to characterize the impact of the Reynolds number, the global equivalence ratio, the progress of mixing within the flame, as well as the mixing length on the mixing field. Furthermore, these effects are evaluated by means of a regime diagram for partially premixed flames. In this study, it is shown that the increase of the mixing length results in a significantly more stable flame. The impact of the Reynolds number on flame stability is found to be minor.

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The Mixing Field and Flame Structure Near the Reaction Zone of Turbulent Planar Flames at Different Levels of Mixture Inhomogeneity

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Selection of second-generation crop for biodiesel extraction and testing its impact with nano additives on diesel engine performance and emissions

Energy, 2021

Abstract The scope of this study was twofold: to define the most suitable Egypt's biodiesel s... more Abstract The scope of this study was twofold: to define the most suitable Egypt's biodiesel source, and to assess the impact of this biodiesel source with the addition of carbon nano additives on diesel engine performance and emissions. Environmental Key Performance Indicators were used as metrics to identify the appropriate biodiesel source with respect to several criteria including environmental, economic, ecological, and demographic situation. The most suitable Egypt's biodiesel source was identified from different sources including algae, Jatropha, coffee waste, rice straw, sugarcane, and switchgrass. Then, the production process of biodiesel from this renewable source by transesterification was carried out using chemical catalyst or biocatalyst. Following this, this source's impact with carbon nano additives on the performance and emissions of a 0.825-L single-cylinder diesel engine was further examined at engine loads varying between 0 and 4 kW and 1500 rpm constant engine speed. The carbon nano additives were added at a different mass fractions of 25, 50 and 100 ppm to Jatropha biodiesel and diesel blend (20 % jatropha biodiesel+ 80 % diesel) by volume. The results showed Jatropha as the most efficient biodiesel source among all the tested fuels to be produced in Egypt. Furthermore, the experimental engine test results revealed that Jatropha biodiesel without and with carbon nano additives consistently has a higher brake thermal efficiency and lower brake specific fuel consumption in comparison to that of diesel fuel. Likewise, Jatropha biodiesel without and with carbon nano additives enhanced the engine performance and consequently reduced the exhaust emissions including CO, CO2, HC, NOx, and smoke in comparison to that of diesel fuel.

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Ninth Mediterranean Combustion Symposium

Combustion Science and Technology, May 3, 2016

before, the objective of the symposium was to give combustion scientists, engineers and students ... more before, the objective of the symposium was to give combustion scientists, engineers and students from Mediterranean as well as from other countries, an opportunity to get together for the dissemination of the international state-of-the-art and recent advances in the field and to enhance future collaborative research activities between scientists from different countries of the region. About 280 scientists from all over the world participated in the meeting. The program included 6 invited lectures, 5 parallel sessions for oral presentation and a poster session. The invited lectures were delivered by well-known experts in the field (J.

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Eighth Mediterranean Combustion Symposium

Combustion Science and Technology, Apr 23, 2014

The Eighth Mediterranean Combustion Symposium, jointly co-sponsored by the Combustion Institute a... more

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Effect of Ni-Ferrite and Ni-Co-Ferrite nanostructures on biogas production from anaerobic digestion

Fuel, 2019

Many Nanoparticles (NPs) were reported to significantly enhance the production of biogas from the... more Many Nanoparticles (NPs) were reported to significantly enhance the production of biogas from the anaerobic digestion of organic wastes. Herein, two types of NPs (Ni-Ferrite and Ni-Co-Ferrite) were synthesized using the co-precipitation method and characterized using X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy (EDS) techniques. Three different concentrations (20, 70 and 130 mg/l) of each type were added to separate biogas reactors to study their effect on the biogas production compared to blank reactor. A pressure-based biogas reactor was designed and manufactured specifically to test the effect of the NPs on the anaerobic digestion process. The pressure of the daily produced biogas was monitored using a pressure transducer and the volume of the biogas was calculated at standard conditions of pressure (1.013 bar) and temperature (15°C). The results showed an increase in the biogas production of 6.6%, 5.9% and 32.9% upon the use of Ni-Co-Ferrite NPS at concentrations of 20, 70, and 130 mg/l compared to blank reactor, respectively. In addition, the Ni-Ferrite NPs achieved biogas enhancements of 30.8%, 28.5%, and 17.9% at concentrations of 20, 70 and 130 mg/l, respectively.

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Development of the Stability on the Laser System Used at Satellite Laser Ranging Station

The Open Nuclear & Particle Physics Journal

A level of the Nd:YAG oscillator stability has been experimentally determined for different setup... more A level of the Nd:YAG oscillator stability has been experimentally determined for different setups of resonator Q-switches. Performed experiments quantify an influence of an active modulation element on generated laser pulses stability. Different types of saturable absorbers were investigated and improved stability of double switching (active mode locker plus passive saturable absorber mode-locker) was confirmed. The best stability has been achieved with the aid of dual switching of an acousto-opticmodulator and a saturable absorber-dye solution 3955 in ethylalcohol to be used for satellite laser radar station at Helwan city in Egypt. The energy stability of the laser output can improve the accuracy and reliability of the satellite laser ranging station. The oscillator output picosecond pulses resulting from both the saturable absorber dye and three different multiple quantum well (semiconductor) saturable absorbers have been compared.Experimental results revealed that thedye ML51 m...

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A concentric flow slot burner for turbulent flames of partially premixed and inhomogeneous mixtures of gaseous fuels

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Mapping the stability of free-jet biogas flames under partially premixed combustion

Energy, Apr 1, 2021

Abstract Enhancement of biogas combustion characteristics will increase the possibility of the di... more Abstract Enhancement of biogas combustion characteristics will increase the possibility of the direct utilization of such an eco-friendly fuel in practical combustors. We report a full study of biogas combustion under partially premixed mode to investigate the stability of biogas free-jet flames using a concentric flow slot burner was used to evaluate the biogas combustion characteristics. Five mixtures of biogas ranging from 0%CO2 up to 40%CO2 were investigated to study the effect of CO2 proportion on the stability of biogas flames. A new well-defined stability procedure was followed by studying the four major observed phenomena in biogas flames: Stable Flame, Partially-lifted Flame, Fully-lifted Flame, and Extinction. Each phenomenon was clearly defined in addition to describing the operating conditions in terms of Reynolds Number (Re) and Equivalence ratio (ϕ). The effect of the premixing ratio (LD) on the combustion stability of biogas flames was also studied for five premixing ratios LD3, LD5, LD7, LD10, and LD16 to optimize the flame stability. The temperature of stable biogas flames was also measured at different CO2 percentages. The results showed that LD10 is the optimum premixing ratio to generate a stable biogas flame at all tested CO2 proportions. Partially premixed combustion in slot burner manages to sustain a stable biogas flame up to 30%CO2. However, increasing the CO2 to 40% eventually led to a weak and unstable flame regardless of the premixing ratio.

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Ninth Mediterranean Combustion Symposium

Experimental Thermal and Fluid Science, May 1, 2016

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Fourth Mediterranean Combustion Symposium

Experimental Thermal and Fluid Science, Apr 1, 2007

... Mohy S. Mansour, The American University in Cairo, Cairo, Egypt Pinar Menguc, University of K... more

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Highly stabilized partially premixed flames of propane in a concentric flow conical nozzle burner with coflow

Experimental Thermal and Fluid Science, Jul 1, 2018

Partially premixed turbulent flames with non-homogeneous jet of propane were generated in a conce... more Partially premixed turbulent flames with non-homogeneous jet of propane were generated in a concentric flow conical nozzle burner in order to investigate the effect of the coflow on the stability and flame structure. The flame stability is first mapped and then high-speed stereoscopic particle image velocimetry, SPIV, plus OH planar laserinduced fluorescence, OH-PLIF, measurements were conducted on a subset of four flames. The jet equivalence ratio Φ = 2, Jet exit Reynolds number Re = 10,000, and degree of premixing are kept constant for the selected flames, while the coflow velocity, Uc, is progressively changed from 0 to 15 m/s. The results showed that the flame is stable between two extinction limits of mixture inhomogeneity, and the optimum stability is obtained at certain degree of mixture inhomogeneity. Increasing Φ, increases the span between these two extinction limits, while these limits converge to a single point (corresponding to optimum mixture inhomogeneity) with increasing Re. Regardless the value of Φ, increasing the coflow velocity improves the flame stability. The correlation between recessed distance of the burner tubes and the fluctuation of the mixture leads to optimum flame stability. The time averaged SPIV results show that the coflow induces a big annular recirculation zone surrounds the jet flames. The size and the location of this zone is seen to be sensitive to Uc. However, the instantaneous images show the existence of a small vortical structure close to the shear layer, where the flame resides there in the case of no-coflow. These small vertical structures are seen playing a vital role in the flame structure, and increasing the flame corrugation close to the nozzle exit. Increasing the coflow velocity expands the central jet at the expense of the jet velocity, and drags the flame in the early flame regions towards the recirculation zone, where the flame tracks and matches the spatial locations of low axial velocity fluctuations. At downstream, the flame is seen to conform to the passage of large scale structure. At Uc = 10 and 15 m/s, part of the primary reaction zone is rolled up towards upstream burner nozzle, anchoring the flame to the nozzle tip. This indicates that the

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A concentric flow slot burner for stabilizing turbulent partially premixed inhomogeneous flames of gaseous fuels

Experimental Thermal and Fluid Science, Feb 1, 2018

Combustion of turbulent inhomogeneous mixtures of air and fuel is common in many practical system... more Combustion of turbulent inhomogeneous mixtures of air and fuel is common in many practical systems providing improved stability for both gaseous and liquid fuels. Understanding the structure and stability of turbulent flames in this mode has been the aim of many research groups who employed special burner designs to control the fuel and air mixing process. In this work, a modified design inspired by the Wolfhard-Parker slot burner was developed for planar turbulent flames with inlet conditions that are overall lean yet either compositionally inhomogeneous or partially premixed. The new burner is referred as the Concentric Flow Slot Burner (CFSB). The stability characteristics and flame structure are investigated for methane and natural gas fuels using planar laser induced fluorescence of C 2 H x and high speed PLIF-OH. The effects of the jet equivalence ratio, the level of inhomogeneity, and the Reynolds number are investigated in this work. The data show that the flames with inhomogeneous mixture are more stable than fully premixed flames. Lean flames are stabilized in the CFSB burner. Stability is significantly improved by the use of a hollow truncated rectangular pyramid nozzle at the burner exit. The reaction zone structure varies significantly in the current burner from thin structures in rich flames to distributed with thick preheat zones in lean flames. The effect of the level of inhomogeneity on the reaction zone structure is presented and discussed. The new CFSB burner is able to generate a wide range of turbulent planar flames spanning the entire range from non-premixed to fully premixed flames. In addition, the high stability level of the burner allows for the study of highly turbulent flames of practical interest.

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Eighth Mediterranean Combustion Symposium

Experimental Thermal and Fluid Science, Jul 1, 2014

The Eighth Mediterranean Combustion Symposium, jointly co-sponsored by the Combustion Institute a... more

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Detailed investigation of the mixing field and stability of natural gas and propane in highly turbulent planar flames

Fuel, Feb 1, 2022

Abstract In most practical combustion devices, the actual combustion process occurs within differ... more Abstract In most practical combustion devices, the actual combustion process occurs within different mixture inhomogeneity levels. Investigating the mixture fraction field upstream of the reaction zones of these flames is an essential step toward understanding their structure, stability, and emission formation. In this study, the mixture fraction fields were measured for turbulent non-reacting inhomogeneous mixtures immediately downstream from the slot burner exit, using Rayleigh scattering imaging. The slot burner had two concentric slots. The inner air slot can be recessed at distances upstream from the exit of the outer fuel slot, allowing various degrees of mixture inhomogeneity. Mixture fraction field statistics and the two-dimensional gradient were utilized to characterize the impact of the air-to-fuel velocity ratio, global equivalence ratio, fuel composition, Reynolds number, and the premixing length on the mixture mixing field, and thus flame stability. These impacts were evaluated by tracking the normalized mean mixture fraction and mixture fraction fluctuation transition across the regime diagram for partially premixed flames. The results showed that the air-to-fuel velocity ratio was the critical parameter affecting the mixture fraction field for the short premixing length. Stability results showed that the level of mixture inhomogeneity mainly influenced the flame stability. High flame stability is achieved if a large portion of the inhomogeneous mixture fraction is within the fuel flammability limits.

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Flame stability and equivalence ratio assessment of turbulent partially premixed flames

Fuel

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$Research paper thumbnail of Simultaneous line Raman/Rayleigh measurements for mixture fraction determination in turbulent, partially premixed slot burner flames$

Simultaneous line Raman/Rayleigh measurements for mixture fraction determination in turbulent, partially premixed slot burner flames

In many applied combustion systems, fuel and air are neither homogeneously mixed nor fully separa... more In many applied combustion systems, fuel and air are neither homogeneously mixed nor fully separated before reactions occur. Mixture fraction statistics expressed as mean and fluctuation root mean square seem appropriate quantities for partially premixed flame characterization in a regime diagram [1]. In order to measure the mixture fraction and the temperature in turbulent partially premixed slot burner flames, a simultaneous, one dimensional Raman and Rayleigh technique is applied in this study. Averaged mixture fractions and their fluctuations determined in the unburnt region at different flame positions are plotted in the regime diagram. It is found that the Reynolds number has only insignificant effects on partially premixed flame stability, while time for mixing is the driving parameter to stabilize partially premixed flames.

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Lean partially premixed turbulent flame equivalence ratio measurements using laser-induced breakdown spectroscopy

Fuel, 2019

NOTICE: this is the author's version of a work that was accepted for publication in Fuel. Changes... more NOTICE: this is the author's version of a work that was accepted for publication in Fuel. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in

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Seventh Mediterranean Combustion Symposium

Combustion Science and Technology, 2012

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Fifth Mediterranean Combustion Symposium

Experimental Thermal and Fluid Science, 2008

As before, the objective of the symposium was to give combustion scientists, engineers and studen... more As before, the objective of the symposium was to give combustion scientists, engineers and students from the Mediterranean as well as from other countries an opportunity to get together for the dissemination of the international state-of-the-art and recent advances in the field and to enhance future collaborative research activities between scientists from different countries in the region.

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Preface: Advanced Analysis of Turbulent Combustion

Flow Turbulence and Combustion, 2016

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Preface: Special Issue: Advances in Turbulent Combustion

The Tenth Mediterranean Combustion Symposium (MCS10), jointly cosponsored by the Combustion Insti... more The Tenth Mediterranean Combustion Symposium (MCS10), jointly cosponsored by the Combustion Institute and the International Centre for Heat and Mass Transfer, was held in Naples, Italy in September 17-21, 2017. This special issue contains 13 papers selected from a total of 171 papers presented during the MCS10 Symposium. The objective of the symposium was to give combustion scientists, engineers and students from Mediterranean as well as from other countries an opportunity to get together for the dissemination of the international state-ofthe-art and recent advances in the field, so as to enhance future collaborative research activities between scientists from different countries of the region. This special issue of Flow Turbulence and Combustion is the fourth of the series, which started with the Seventh Mediterranean Combustion Symposium, and the papers were selected and reviewed on the basis of their quality as judged by the reviewers in relation to the aims and scope of the Journal. All papers published in this Special Issue were subjected to the same rigorous peer-review process as normal submissions to the Journal. It was therefore independent from the review of the conference submissions, which was used only in order to select the authors that were invited to submit a paper for this volume. The Guest Editors are grateful for the opportunity to publish this volume, which makes a substantial contribution to advancing the field of turbulent combustion of gaseous as well as liquid fuels.

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Preface - Fifth Mediterranean Combustion Symposium

Combustion Science and Technology

Photoelectron spectroscopy has its roots in the Nobel Prize-winning work of Albert Einstein and K... more Photoelectron spectroscopy has its roots in the Nobel Prize-winning work of Albert Einstein and Kai Siegbahn. It is therefore both an honor and a humbling experience to produce a book that documents the excitement of the newest developments in this field. According to Einstein’s discovery of the law of the photoelectric effect, considered to be the dawn of the quantum age, the conservation of energy between the incoming photon and the outgoing photoelectron in the photoemission process allows the technique to uniquely measure the chemical and electronic structure of atoms, molecules, and solids. However, despite Seigbahn’s original development of the technique for chemical analysis with high-energy X-rays, the use of low-energy photons with energies up to only about 1.5 keV by modern researchers, at both laboratory and synchrotron sources, results in extremely short photoelectron inelastic mean-free paths. As a result, this limited information depth has historically restricted experiments to the study of surfaces and shallow interfaces, or what is referred to in the literature as traditional surface science. It is therefore no surprise that recent advances in both photon source and electron-spectrometer instrumentation have driven experiments into the extended 2–10 keV photon energy range resulting in what is now called hard X-ray photoelectron spectroscopy (HAXPES). Due to its relatively unlimited electron escape depths, HAXPES has emerged as a powerful tool that has general application to the study of the true bulk and buried interface properties of complex materials systems. Its areas of application are thus growing exponentially compared to more traditional measurements at lower photon energies. In addition to the many advantages of being able to study “real” samples taken directly from air without the need for ion sputtering or other surface preparation, HAXPES has opened up other research areas that are included in this book such as:

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Special Issue: Advances in Combustion Research

Flow Turbulence and Combustion, 2021

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An Experimental Study of the Effect of Partial Premixing Level on the Interaction between the Flame Kernel and Flow Field

Flame kernels in spark-ignited combustion systems dominate the flame propagation and combustion s... more Flame kernels in spark-ignited combustion systems dominate the flame propagation and combustion stability, performance and emissions. The aim of the present work is to investigate the flow field associated with flame kernel propagation history in partial premixing natural gas turbulent flames. The main parameters under investigation are the degree of partial premixing and jet velocity. Three different degrees of partial premixing and five values of jet velocity between10 and 20 m/s have been selected for the present work at an equivalence ratio of 2. The mean flow field and turbulence intensity are measured using two-dimensional Planar Imaging Velocimetry (PIV). A pulsed Nd: YAG laser is used for flame ignition. The turbulent flow field is captured after the ignition at several time intervals between, 150, and 2500 μs after ignition. The results show that the flame kernel does not show any significant effect on the scale of mean flow field. On the other hand, the flame kernel increa...

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Experimental Investigation of Flame Kernel in Turbulent Partial Premixed

The flame kernel propagation is believed to be influenced by many operating parameters such as mi... more The flame kernel propagation is believed to be influenced by many operating parameters such as mixing level, turbulent intensity, and the mixture equivalence ratio. The purpose of this study is to investigate the effect of the mixture equivalence ratio and turbulence intensity on the flame kernel and flow field interlinks in partially premixed natural gas flames. Three jet equivalence ratios of 1, 1.5, and 2 are considered at values of jet velocities in the range from 10 to 20 m/s. This study was done under constant degree of partial premixing. A pulsed Nd: YAG laser is used for the flame ignition, and the turbulent flow field is captured at several time intervals from ignition using two-dimensional Planar Imaging Velocimetry (PIV). The mean flow field doesn’t influence with the flame kernel propagation. The turbulent flow field indicates an increase in the global turbulence intensity in flames associated with the kernel propagation in comparison with the isothermal case. The jet eq...

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Multi-Reaction Zones Imaging Technique for Turbulent Hydrocarbon Flames

Turkish Journal of Engineering and Environmental Sciences, 2006

Detection and imaging of multi-reaction zones is an essential tool for understanding the detailed... more Detection and imaging of multi-reaction zones is an essential tool for understanding the detailed structure of complicated flames. In this work a combined 4-camera technique is presented for multi-reaction zones imaging. The technique combines highly advanced laser-based diagnostics tools, namely Rayleigh scattering, laser-induced predissociation fluorescence (LIPF) of OH, LIF of PAH, and LIF of formaldehyde (CH2O). The application of this combined technique in turbulent non-homogeneous hydrocarbon flames is quite new. The technique shows its ability to detect simultaneously rich, lean and diffusion reaction zones. The 3 reaction zones can be spatially resolved, providing essential information about their interaction and overall flame stability. Therefore, the detection and study of triple flame structures in non-homogeneous turbulent flames becomes possible. An example of a triple flame structure in a turbulent lifted non-premixed methane flame is presented. The present work proves...

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Preface

Flow, Turbulence and Combustion

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Biogas production enhancement using nanocomposites and its combustion characteristics in a concentric flow slot burner

Experimental Thermal and Fluid Science

Biogas combustion is a very essential topic for the development of many industrial combustion sys... more Biogas combustion is a very essential topic for the development of many industrial combustion systems and engines. This fuel can replace current fossil fuels used in burners, engines, and many other applications. Understanding the combustion characteristics of this fuel and its stability in highly turbulent flames of practical interest is the aim of this work. The percentage of CO 2 in Biogas varies between 25% and 45%, which affects the combustion stability and flame structure. The present work shows that the generation of Biogas is improved by adding Ni-Co-Ferrite or Ni-ferrite nano-additives. In this work, we selected 25 flames of mixtures of natural gas and CO 2 , where the ratio of CO 2 varies from 0% to 40%. The flames are generated in a concentric flow slot burner that produces planar two-dimensional flames. The stability characteristics and the flame structure were investigated. The flame structure is presented in the form of temperature profiles in some selected flames using fine wire thermocouple measurements. The stability characteristics are illustrated for two limits of lifted flames and blow out. The production rate of Biogas can be increased by almost 30% using nano-additives of Ni-Co-Ferrite or Ni-ferrite. The data show that the stability of the flames is affected significantly for the 40% CO 2 mixture. Therefore, it is recommended to keep CO 2 percentage up to 30% for stable turbulent Biogas flames. On the other hand, partially premixed flames are highly stable for a certain level of mixture inhomogeneity at a mixing length ratio of L/D = 16. At this level, the mixture fraction fluctuations are expected to be within the flammability limits range based on previous investigations in round jet configuration.

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Can microwave treat biomass tar? A comprehensive study based on experimental and net energy analysis

Applied Energy

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Study on NOx emission during corn straw/sewage sludge co-combustion: Experiments and modelling

Fuel

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Preface: Tenth Mediterranean Combustion Symposium

Fuel

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Advances in Combustion Research

Flow, turbulence and combustion, Mar 19, 2024

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Computer aided design, optimization and performance enhancement of solid state laser cavities

by Samy Ghoniemy and Mohy Mansour

The International Conference on Applied Mechanics and Mechanical Engineering, 2010

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Laser Accelerators

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Effect of Partial Premixing on Stabilization and Local Extinction of Turbulent Methane/Air Flames

Flow, turbulence and combustion, Sep 18, 2012

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Laser science and applications : proceedings of the sixth international conference, National Institute of Laser Enhanced Sciences, Cairo University, Egypt, 15-18 January 2007

WORLD SCIENTIFIC eBooks, 2010

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Laser-Based Techniques for Temperature and Species Measurements

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$Research paper thumbnail of Evaluation of partially premixed flame stability from mixture fraction statistics in a turbulent slot burner$

Evaluation of partially premixed flame stability from mixture fraction statistics in a turbulent slot burner

HAL (Le Centre pour la Communication Scientifique Directe), 2017

International audienc

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Structure and stability characteristics of turbulent planar flames with inhomogeneous jet in a concentric flow slot burner

Proceedings of the Combustion Institute, 2021

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