Measurement of Laminar Burning Speeds and Determination of Onset of Auto-Ignition of Jet-A/Air and Jet Propellant-8/Air Mixtures in a Constant Volume Spherical Chamber

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Ali Moghaddas ◽  
Casey Bennett ◽  
Kian Eisazadeh-Far ◽  
Hameed Metghalchi
Keyword(s):  
High Pressures ◽  
Dynamic Pressure ◽  
Combustion Process ◽  
Pressure Rise ◽  
Constant Volume ◽  
Pressure Data ◽  
Spherical Vessel ◽  
Auto Ignition ◽  
Made In

The laminar burning speeds of Jet-A/air and three different samples of jet propellant (JP-8)/air mixtures have been measured and the onset of auto-ignition in JP-8/air premixed mixtures has been determined. The experiments were made in a constant volume spherical vessel, which can withstand high pressures up to 400 atm. Burning speed was calculated from dynamic pressure rise due to the combustion process in the vessel. A thermodynamic model based on the pressure rise was used to determine the burning speed. The burning speeds were measured in lean mixtures for pressures of 1–4.5 atm and temperatures of 493–700 K. The onset of auto-ignition of JP-8 fuels was evaluated by observing intense fluctuations of pressure data during the explosion of the unburned gas. It was revealed that Jet-A and JP-8 have very similar burning speeds; however, auto-ignition temperatures of various samples of JP-8 were slightly different from each other. Auto-ignition of these fuels was much more sensitive to temperature rather than pressure.

Auto-Ignition Characteristics Study of Gas-to-Liquid Fuel at High Pressures and Low Temperatures

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Omid Askari ◽  
Mimmo Elia ◽  
Matthew Ferrari ◽  
Hameed Metghalchi
Keyword(s):  
Chemical Kinetics ◽  
Low Temperatures ◽  
High Speed ◽  
High Pressures ◽  
Initial Temperature ◽  
Combustion Process ◽  
Pressure Rise ◽  
Auto Ignition ◽  
Wide Range ◽  
Gas To Liquid

Onset of auto-ignition of premixed gas-to-liquid (GTL)/air mixture has been determined at high pressures and low temperatures over a wide range of equivalence ratios. The GTL fuel used in this study was provided by Air Force Research Laboratory (AFRL), designated by Syntroleum S-8, which is derived from natural gas via the Fischer–Tropsch (F–T) process. A blend of 32% iso-octane, 25% n-decane, and 43% n-dodecane is employed as the surrogates of GTL fuel for chemical kinetics study. A spherical chamber, which can withstand high pressures up to 400 atm and can be heated up to 500 K, was used to collect pressure rise data, due to combustion, to determine the onset of auto-ignition. A gas chromatograph (GC) system working in conjunction with specialized heated lines was used to verify the filling process. A liquid supply manifold was used to allow the fuel to enter and evaporate in a temperature-controlled portion of the manifold using two cartridge heaters. An accurate high-temperature pressure transducer was used to measure the partial pressure of the vaporized fuel. Pressure rise due to combustion process was collected using a high-speed pressure sensor and was stored in a local desktop via a data acquisition system. Measurements for the onset of auto-ignition were done in the spherical chamber for different equivalence ratios of 0.8–1.2 and different initial pressures of 8.6, 10, and 12 atm at initial temperature of 450 K. Critical pressures and temperatures of GTL/air mixture at which auto-ignition takes place have been identified by detecting aggressive oscillation of pressure data during the spontaneous combustion process throughout the unburned gas mixture. To interpret the auto-ignition conditions effectively, several available chemical kinetics mechanisms were used in modeling auto-ignition of GTL/air mixtures. For low-temperature mixtures, it was shown that auto-ignition of GTL fuel is a strong function of unburned gas temperature, and propensity of auto-ignition was increased as initial temperature and pressure increased.

Measurement of Laminar Burning Speeds and Investigation of Flame Stability of Acetylene (C2H2)/Air Mixtures

2014 ◽  
Author(s):  
Emad Rokni ◽  
Ali Moghaddas ◽  
Omid Askari ◽  
Hameed Metghalchi
Keyword(s):  
Flame Propagation ◽  
High Speed ◽  
Dynamic Pressure ◽  
Combustion Process ◽  
Pressure Rise ◽  
Laminar Flames ◽  
Cmos Camera ◽  
Wide Range ◽  
Cellular Flames ◽  
Flame Structures

Laminar burning speeds and flame structures of spherically expanding flames of mixtures of acetylene (C2H2) with air have been investigated over a wide range of equivalence ratios, temperatures, and pressures. Experiments have been conducted in a constant volume cylindrical vessel with two large end windows. The vessel was installed in a shadowgraph system equipped with a high speed CMOS camera, capable of taking pictures up to 40,000 frames per second. Shadowgraphy was used to study flame structures and transition from smooth to cellular flames during flame propagation. Pressure measurements have been done using a pressure transducer during the combustion process. Laminar burning speeds were measured using a thermodynamic model employing the dynamic pressure rise during the flame propagation. Burning speeds were measured for temperature range of 300 to 590 K and pressure range of 0.5 to 3.3 atmospheres, and the range of equivalence ratios covered from 0.6 to 2. The measured values of burning speeds compared well with existing data and extended for a wider range of temperatures. Burning speed measurements have only been reported for smooth and laminar flames.

Laminar Burning Speed Measurements of Premixed JP-8, Oxygen and He Flames

2006 ◽  
Author(s):  
Farzan Parinejad ◽  
Edwin Shirk ◽  
Kian Eisazadeh Far ◽  
Hameed Metghalchi
Keyword(s):  
High Temperatures ◽  
Power Law ◽  
Flame Structure ◽  
Cylindrical Vessel ◽  
Pressure Measurements ◽  
Pressure Data ◽  
Spherical Vessel ◽  
Combustion Pressure ◽  
Made In ◽  
Laminar Burning Speed

The focus of this study is the calculation of the laminar burning speed of JP-8, oxygen, and helium mixtures at high temperatures and pressures. Two constant volume combustion vessels were used for the analysis. The spherical vessel was primarily used for the collection of pressure data from which the burning speed was calculated. A cylindrical vessel was also used in conjunction with a shadowgraph system to observe the flame structure and the onset of instability. Observations of JP-8 with both nitrogen and helium as diluents were made in the cylindrical vessel and it was seen that at a temperature of 200° C over the range of 1-8 atmospheres pressure and equivalence ratios of 0.7-1.0 with helium as the diluent, the flame was laminar throughout its combustion. Pressure measurements of JP-8 and oxygen with helium as the diluent were then made in the spherical vessel. Laminar burning speed of JP-8 with oxygen and helium has been calculated using the spherical vessel pressure data for this range of temperatures, pressures and equivalence ratios. Power law correlations for burning speeds have been developed for these results.

Laminar Burning Velocity of Methane–Air–Diluent Mixtures

2000 ◽  
Vol 123 (1) ◽  
pp. 190-196 ◽  
Author(s):  
M. Elia ◽  
M. Ulinski ◽  
M. Metghalchi
Keyword(s):  
Mass Fraction ◽  
Dynamic Pressure ◽  
Burning Velocity ◽  
Combustion Process ◽  
Numerical Differentiation ◽  
Constant Volume ◽  
Laminar Burning Velocity ◽  
Wide Range ◽  
Energy Equations ◽  
Gas Properties

An experimental facility for measuring burning velocity has been designed and built. It consists of a spherical constant volume vessel equipped with a dynamic pressure transducer, ionization probes, thermocouple, and data acquisition system. The constant volume combustion vessel allows for the determination of the burning velocity over a wide range of temperatures and pressures from a single run. A new model has been developed to calculate the laminar burning velocity using the pressure data of the combustion process. The model solves conservation of mass and energy equations to determine the mass fraction of the burned gas as the combustion process proceeds. This new method allows for temperature gradients in the burned gas and the effects of flame stretch on burning velocity. Exact calculations of the burned gas properties are determined by using a chemical equilibrium code with gas properties from the JANAF Tables. Numerical differentiation of the mass fraction burned determines the rate of the mass fraction burned, from which the laminar burning velocity is calculated. Using this method, the laminar burning velocities of methane–air–diluent mixtures have been measured. A correlation has been developed for the range of pressures from 0.75 to 70 atm, unburned gas temperatures from 298 to 550 K, fuel/air equivalence ratios from 0.8 to 1.2, and diluent addition from 0 to 15 percent by volume.

Measurement of Laminar Burning Speeds and Investigation of Flame Stability of Acetylene (C2H2)/Air Mixtures

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Emad Rokni ◽  
Ali Moghaddas ◽  
Omid Askari ◽  
Hameed Metghalchi
Keyword(s):  
Flame Propagation ◽  
High Speed ◽  
Dynamic Pressure ◽  
Combustion Process ◽  
Pressure Rise ◽  
Laminar Flames ◽  
Cmos Camera ◽  
Wide Range ◽  
Cellular Flames ◽  
Flame Structures

Laminar burning speeds and flame structures of spherically expanding flames of mixtures of acetylene (C2H2) with air have been investigated over a wide range of equivalence ratios, temperatures, and pressures. Experiments have been conducted in a constant volume cylindrical vessel with two large end windows. The vessel was installed in a shadowgraph system equipped with a high speed CMOS camera, capable of taking pictures up to 40,000 frames per second. Shadowgraphy was used to study flame structures and transition from smooth to cellular flames during flame propagation. Pressure measurements have been done using a pressure transducer during the combustion process. Laminar burning speeds were measured using a thermodynamic model employing the dynamic pressure rise during the flame propagation. Burning speeds were measured for temperature range of 300–590 K and pressure range of 0.5–3.3 atm, and the range of equivalence ratios covered from 0.6 to 2. The measured values of burning speeds compared well with existing data and extended for a wider range of temperatures. Burning speed measurements have only been reported for smooth and laminar flames.

Burning Speed Measurement of JP-8 Air Flames

2004 ◽  
Author(s):  
Farzan Parsinejad ◽  
Christian Arcari ◽  
Edwin Shirk ◽  
Hameed Metghalchi
Keyword(s):  
High Speed ◽  
Variable Temperature ◽  
Dynamic Pressure ◽  
Flame Structure ◽  
Pressure Rise ◽  
Ccd Camera ◽  
Cylindrical Vessel ◽  
Spherical Vessel ◽  
Speed Measurement ◽  
Wide Range

Burning speed measurement and structure of JP-8 air mixtures at a wide range of temperature and pressure have been studied using two matched constant volume chambers. The experimental facilities include a spherical chamber and cylindrical vessel with glasses at the end caps to enable us visualizing flame structure. Cylindrical vessel is located in a Schlieren set up including spherical mirrors and a high speed CCD camera. Facilities also include and oven which can raise the initial temperature of the mixtures in spherical vessel to 500 K and similar heating elements that perform the same task in cylindrical chamber. A thermodynamic model has been developed to calculate burning speeds using dynamic pressure rise in the chamber. The model considers a central burned gas core of variable temperature surrounded by an unburned gas shell with uniform temperature with a thermal boundary layer at the wall. Burning speed and flame structure of different gaseous fuel-air mixtures have been investigated. Autoignition characteristics of JP-8 air mixtures have also been determined by the sudden pressure rise in spherical vessel.

Experimental Study of Laminar Burning Speed for Premixed Biomass/Air Flame

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Ziwei Bai ◽  
Ziyu Wang ◽  
Guangying Yu ◽  
Yongping Yang ◽  
Hameed Metghalchi
Keyword(s):  
High Speed ◽  
Combustion Process ◽  
Fundamental Property ◽  
Pressure Rise ◽  
Flame Surface ◽  
Cmos Camera ◽  
One Dimensional ◽  
Co2 Concentrations ◽  
Made In ◽  
Laminar Burning Speed

Biomass has been considered as a valuable alternative fuel recently. A fundamental property of biomass/air flame, laminar burning speed, is measured in this research. Experiments have been made in a cylindrical combustion vessel with two end windows. Central ignition has been used to start the combustion process. A high-speed CMOS camera capable of taking pictures of 40,000 frames per second has been used to study morphology of flame front. Flames are initially smooth, and as pressure and flame radius increase, cracks and cells appear on the flame surface. In this paper, experimental results have only been reported for smooth flames. A multishell thermodynamic model to measure laminar burning speed of biomass/air mixture with varying CO2 concentrations (0%–60%), based on the pressure rise data collected from a cylindrical chamber during combustion, has been developed in this paper. Burning speed has been only reported for flame radii larger than 4 cm in radius in order to have negligible stretch effect. Power law correlations, to predict burning speed of biomass/air mixtures, based on the measured burning speeds, have been developed for a range of temperatures of 300–661 K, pressures of 0.5–6.9 atmospheres, equivalence ratios of 0.8–1.2, and CO2 concentrations 0%–60%. Moreover, the measured laminar burning speeds have been compared with simulation results using a one-dimensional steady-state laminar premixed flame program with GRI-Mech 3.0 mechanism and other available data from literatures. Comparison with existing data has been excellent.

The quantitative comparison of experimental and simulated diffraction contrast images

1995 ◽  
Vol 53 ◽  
pp. 102-103
Author(s):  
Stuart McKernan
Keyword(s):  
Image Processing ◽  
Personal Computer ◽  
Close Agreement ◽  
Quantitative Comparison ◽  
Image Simulation ◽  
Computing Power ◽  
Diffraction Contrast ◽  
Simulated Images ◽  
Made In

For many years the concept of quantitative diffraction contrast experiments might have consisted of the determination of dislocation Burgers vectors using a g.b = 0 criterion from several different 2-beam images. Since the advent of the personal computer revolution, the available computing power for performing image-processing and image-simulation calculations is enormous and ubiquitous. Several programs now exist to perform simulations of diffraction contrast images using various approximations. The most common approximations are the use of only 2-beams or a single systematic row to calculate the image contrast, or calculating the image using a column approximation. The increasing amount of literature showing comparisons of experimental and simulated images shows that it is possible to obtain very close agreement between the two images; although the choice of parameters used, and the assumptions made, in performing the calculation must be properly dealt with. The simulation of the images of defects in materials has, in many cases, therefore become a tractable problem.

Science of Ahangyol and Its Importance for Modern Scientific Thought

2019 ◽  
Vol 10 (5) ◽  
pp. 473-478
Author(s):  
Ahmad Gashamoglu ◽  
Keyword(s):  
Modern Science ◽  
Scientific Basis ◽  
New Paradigm ◽  
Islamic Philosophy ◽  
Scientific Thought ◽  
Religious Books ◽  
Strategic Approach ◽  
Scientific Potential ◽  
Made In

The Article briefly discusses the need for generation of the Science of Ahangyol, and this science’s scientific basis, object and subject, category system, scientific research methods and application options. Ahangyol is a universal science and may be useful in any sphere. It may assist in problem solving in peacemaking process and in many areas such as ecology, economics, politics, culture, management and etc. This science stipulates that any activity and any decision made in the life may only and solely be successful when they comply with harmony principles more, which are the principles of existence and activity of the world. A right strategic approach of the Eastern Philosophy and the Middle Age Islamic Philosophy and scientific thought has an important potential. This strategic approach creates opportunities to also consider irrational factors in addition to rational ones comprehensively in scientific researches. The modern scientific thought contributes to implementation of these opportunities. Ahangyol is a science of determination of ways to achieve harmony in any sphere and of creation of special methods to make progress in these ways through assistance of the modern science. Methods of the System Theory, Mathematics, IT, Astronomy, Physics, Biology, Sociology, Statistics and etc. are more extensively applied. Information is given on some of these methods. Moreover, the Science of Ahangyol, which is a new philosophical worldview and a new paradigm contributes to clarification of metaphysic views considerably and discovery of the scientific potential of religious books.

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