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.

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.

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.

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.

Effect of Carbon Dioxide on the Laminar Burning Speed of Propane–Air Mixtures

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Sai C. Yelishala ◽  
Ziyu Wang ◽  
Hameed Metghalchi ◽  
Yiannis A. Levendis ◽  
Kumaran Kannaiyan ◽  
...  
Keyword(s):  
High Speed ◽  
Pressure Rise ◽  
Gas Temperature ◽  
Cmos Camera ◽  
Primary Input ◽  
One Dimensional ◽  
Schlieren System ◽  
Co2 Concentrations ◽  
Constant Volume Chamber ◽  
Laminar Burning Speed

This experimental research examined the effect of CO2 as a diluent on the laminar burning speed of propane–air mixtures. Combustion took place at various CO2 concentrations (0–80%), different equivalence ratios (0.7<ϕ<1.2) and over a range of temperatures (298–420 K) and pressures (0.5–6.2 atm). The experiments were performed in a cylindrical constant volume chamber with a Z-shaped Schlieren system, coupled with a high-speed CMOS camera to capture the propagation of the flames at speeds up to 4000 frames per second. The flame stability of these mixtures at different pressures, equivalence ratios, and CO2 concentrations was also studied. Only laminar, spherical, and smooth flames were considered in measuring laminar burning speed. Pressure rise data as a function of time during the flame propagation were the primary input of the multishell thermodynamic model for measuring the laminar burning speed of propane-CO2-air mixtures. The laminar burning speed of such blends was observed to decrease with the addition of CO2 and to increase with the gas temperature. It was also noted that the laminar burning speed decreases with increasing pressure. The collected experimental data were compared with simulation data obtained via a steady one-dimensional (1D) laminar premixed flame code from Cantera, using a detailed H2/CO/C1–C4 kinetics model encompassing 111 species and 784 reactions.

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.

Modification of the magnetosheath due to the high-speed jets propagation.

2020 ◽  
Author(s):  
Oleksandr Goncharov ◽  
Herbert Gunell ◽  
Maria Hamrin ◽  
Linus Norenius ◽  
Olga Gutynska
Keyword(s):  
Statistical Analysis ◽  
Velocity Component ◽  
High Speed ◽  
Dynamic Pressure ◽  
Cone Angle ◽  
Bow Shock ◽  
The Earth ◽  
Magnetospheric Multiscale ◽  
Wide Range ◽  
Statistical Studies

&lt;p&gt;Plasmoids, defined as plasma entities with a higher anti-sunward velocity component than the surrounding plasma, have been observed in the magnetosheath in recent years. Among other denominations, plasmoids are also called &amp;#8220;magnetosheath jets&amp;#8221; and can be classified by transient localized enhancements in dynamic pressure. Propagating through the magnetosheath, jets do not only affect the magnetopause and magnetosphere. Jets pushed slower ambient magnetosheath plasma out of their way. As a result, plasma moves around the jets, and it is slowed down or could even be pushed in the sunward direction. Consequently, jets may create anomalous flows and be a source of additional turbulence. Using the magnetosheath measurements by the Magnetospheric Multiscale (MMS) and THEMIS spacecraft, and comparing several criteria, we have identified several thousand events in the wide range of bow shock distances. Previous statistical studies have shown that jet occurrence is almost exclusively controlled by the angle between the IMF and the Earth&amp;#8211;Sun line (cone angle), and jets are predominantly observed when this cone angle is small. However, high-speed jets downstream of the quasi-perpendicular bow shock are very common. Our statistical analysis shows differences of jets evolution in the quasi-parallel and quasi-perpendicular magnetosheath regions. We discuss their properties, nature and relation to anomalies regions in the magnetosheath.&lt;/p&gt;

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.

Combustion in High-Speed Direct Injection Diesel Engines—A Comprehensive Study

1994 ◽  
Vol 208 (4) ◽  
pp. 223-240 ◽  
Author(s):  
D E Winterbone ◽  
D A Yates ◽  
E Clough ◽  
K K Rao ◽  
P Gomes ◽  
...  
Keyword(s):  
High Speed ◽  
Direct Injection ◽  
Combustion Process ◽  
Operating Conditions ◽  
Correlation Technique ◽  
Full Field ◽  
Combustion Gases ◽  
Carbon Particles ◽  
Wide Range ◽  
Cross Correlation Technique

This paper reports the latest results of a comprehensive project investigating the performance of a Ricardo Hydra direct injection diesel engine. Early work covered a number of aspects of research into the gross behaviour of this engine: this paper concentrates on techniques for obtaining quantitative data from photographs of the combustion process. High-speed photographs, at framing rates up to 20 000 frames/s, were taken using a piston with a quartz bowl, at engine speeds up to 3000 r/min. The pre-combustion period was illuminated using a synchronized copper vapour laser. After the initiation of combustion, the process is self-illuminating and information on the combustion process was obtained by analysing the radiation emitted by the carbon particles. The two-colour method was used to evaluate the temperature of the combustion gases over the full field of view. The images have also been analysed by a cross-correlation technique to obtain velocity information. Tests have been performed on the engine over a wide range of operating conditions, but this paper concentrates on the effect of swirl ratio on combustion. It will be shown that too much swirl increases the ignition delay period and results in an increase in the NOx emissions but a decrease in the soot. It will also be shown that the velocity pattern after combustion is in good agreement with that evaluated by Arcoumanis et al. at the end of compression, which implies that swirl persists through the combustion period despite significant decay.

Ignition and Flame Propagation in Oxy-Methane Mixtures Diluted With CO2

2015 ◽  
Author(s):  
Bader Almansour ◽  
Luke Thompson ◽  
Joseph Lopez ◽  
Ghazal Barari ◽  
Subith S. Vasu
Keyword(s):  
Flame Propagation ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Dynamic Pressure ◽  
Burning Velocity ◽  
Reaction Rates ◽  
Current Data ◽  
Initiation And Propagation ◽  
Experimental Values ◽  
Good Agreement

Ignition and flame propagation in methane/O2 mixtures diluted with CO2 are studied. A laser ignition system and dynamic pressure data are utilized to ignite the mixture and to record the combustion pressure, respectively. The laminar burning velocities (LBV) are obtained at room temperature and atmospheric pressure in a spherical combustion chamber. Flame initiation and propagation is recorded by using a high-speed camera in select experiments to visualize the effect of CO2 proportionality on the combustion behavior. The laminar burning velocity is studied for a range of equivalence ratios (ϕ =0.8–1.3, in steps of 0.1), and oxygen ratios, D=O2/(O2+CO2) (26–38% by volume). It was found that the LBV decreases by increasing the CO2 proportionality. It was observed that the flame propagates toward the laser at a faster rate as the CO2 proportionality increases. Current experiments are in very good agreement with existing literature data. The premixed flame model from CHEMKIN PRO [1] software and two mechanisms (GRI-Mech 3.0 [2] and ARAMCO Mech 1.3 [3]) are used to simulate the current data. In general, simulations are in reasonable agreement with current data though the mechanisms predict slower flame speeds. The LBV values obtained by the ARAMCO 1.3 mechanism are closer to the experimental values. Additionally, sensitivity analysis is carried out to understand the important reactions that influence the predicted flame speeds. Improvements to the GRI predictions are suggested after incorporating latest reaction rates from literature for key reactions.

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