Combustion Characteristics and Laminar Flame Speed of Premixed Ethanol-Air Mixtures with Laser-Induced Spark Ignition

2017 ◽  
Vol 2 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Cangsu Xu ◽  
Anhao Zhong ◽  
Chongming Wang ◽  
Chaozhao Jiang ◽  
Xiaolu Li ◽  
...  
Keyword(s):  
High Speed ◽  
Laminar Flame ◽  
Pressure Rise ◽  
Spark Ignition ◽  
Laser Wavelength ◽  
Combustion Characteristics ◽  
Flame Speed ◽  
Maximum Pressure ◽  
Laminar Flame Speed ◽  
Combustion Duration

AbstractLaser-induced spark-ignition (LISI) has an advanced ignition technique with a few benefits over spark ignition. In this study, flame morphology, laminar flame characteristics and combustion characteristics of premixed anhydrous ethanol and air mixtures were investigated using LISI generated by a Q-switched Nd: YAG laser (wavelength: 1064 nm). Experiments were conducted in a constant volume combustion chamber (CVCC) at the initial condition of T0=358 K and P0=0.1 MPa, respectively, and with equivalence ratios (ɸ) of 0.6-1.6. Flame images were recorded by using the high-speed Schlieren photography technique, and the in-vessel pressure was recorded using a piezoelectric pressure transducer. Tests were also carried out with spark ignition, and the results were used as a reference. It has been found that the laminar flame speed of ethanol-air mixtures with LISI was comparable with those of spark ignition, proving that ignition methods have no influence on laminar flame speed which is an inherent characteristic of a fuel-air mixture. The peak laminar burning velocities for LISI and spark ignition with nonlinear extrapolation methods were approximately 50 cm/s at ɸ=1.1. However, LISI was able to ignite leaner mixtures than spark ignition. The maximum pressure rise rate of LISI was consistently higher than that of spark ignition at all tested ɸ, although the maximum pressure was similar for LISI and spark ignition. The initial combustion duration and main combustion duration reached the minimum at ɸ=1.1.

Laminar flame speed correlations for methane, ethane, propane and their mixtures, and natural gas and gasoline for spark-ignition engine simulations

2017 ◽  
Vol 18 (9) ◽  
pp. 951-970 ◽  
Author(s):  
Riccardo Amirante ◽  
Elia Distaso ◽  
Paolo Tamburrano ◽  
Rolf D Reitz
Keyword(s):  
Natural Gas ◽  
Laminar Flame ◽  
Spark Ignition ◽  
Flame Speed ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Computational Time ◽  
Laminar Flame Speed ◽  
Spark Ignition Engines ◽  
Empirical Correlations

The laminar flame speed plays an important role in spark-ignition engines, as well as in many other combustion applications, such as in designing burners and predicting explosions. For this reason, it has been object of extensive research. Analytical correlations that allow it to be calculated have been developed and are used in engine simulations. They are usually preferred to detailed chemical kinetic models for saving computational time. Therefore, an accurate as possible formulation for such expressions is needed for successful simulations. However, many previous empirical correlations have been based on a limited set of experimental measurements, which have been often carried out over a limited range of operating conditions. Thus, it can result in low accuracy and usability. In this study, measurements of laminar flame speeds obtained by several workers are collected, compared and critically analyzed with the aim to develop more accurate empirical correlations for laminar flame speeds as a function of equivalence ratio and unburned mixture temperature and pressure over a wide range of operating conditions, namely [Formula: see text], [Formula: see text] and [Formula: see text]. The purpose is to provide simple and workable expressions for modeling the laminar flame speed of practical fuels used in spark-ignition engines. Pure compounds, such as methane and propane and binary mixtures of methane/ethane and methane/propane, as well as more complex fuels including natural gas and gasoline, are considered. A comparison with available empirical correlations in the literature is also provided.

A Laminar Burning Velocity Correlation for Hydrogen/Air Mixtures Valid at Spark-Ignition Engine Conditions

2003 ◽  
Author(s):  
Sebastian Verhelst ◽  
Roger Sierens
Keyword(s):  
Chemical Kinetics ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Spark Ignition ◽  
Flame Speed ◽  
Spark Ignition Engine ◽  
Laminar Flame Speed ◽  
Spark Ignition Engines ◽  
Laminar Burning Velocity ◽  
Velocity Correlation

During the development of a quasi-dimensional simulation programme for the combustion of hydrogen in spark-ignition engines, the lack of a suitable laminar flame speed formula for hydrogen/air mixtures became apparent. A literature survey shows that none of the existing correlations covers the entire temperature, pressure and mixture composition range as encountered in spark-ignition engines. Moreover, there is ambiguity concerning the pressure dependence of the laminar burning velocity of hydrogen/air mixtures. Finally, no data exists on the influence of residual gases. This paper looks at several reaction mechanisms found in the literature for the kinetics of hydrogen/oxygen mixtures, after which one is selected that corresponds best with available experimental data. An extensive set of simulations with a one-dimensional chemical kinetics code is performed to calculate the laminar flame speed of hydrogen/air mixtures, in a wide range of mixture compositions and initial pressures and temperatures. The use of a chemical kinetics code permits the calculation of any desired set of conditions and enables the estimation of interactions, e.g. between pressure and temperature effects. Finally, a laminar burning velocity correlation is presented, valid for air-to-fuel equivalence ratios λ between 1 and 3 (fuel-to-air equivalence ratio 0.33 < φ < 1), initial pressures between 1 bar and 16 bar, initial temperatures between 300 K and 800 K and residual gas fractions up to 30 vol%. These conditions are sufficient to cover the entire operating range of hydrogen fuelled spark-ignition engines.

An Investigation of Laminar Flame Speed of CH4-O2-CO2 Mixtures

2019 ◽  
Author(s):  
Mattias A. Turner ◽  
Tyler Paschal ◽  
Waruna D. Kulatilaka ◽  
Eric L. Petersen
Keyword(s):  
Supercritical Co2 ◽  
Carbon Capture ◽  
High Speed ◽  
Laminar Flame ◽  
Full Range ◽  
Methane Combustion ◽  
Fuel Combustion ◽  
Flame Speed ◽  
Working Fluid ◽  
Laminar Flame Speed

Abstract The push for lower carbon emissions in power generation has driven interest in methods of carbon capture and sequestration. One such promising method involves the supercritical CO2 (sCO2) power cycle, a system which is powered by oxy-fuel combustion where supercritical carbon dioxide is used as the working fluid. The high CO2 concentration in the combustion products allows for relatively simple extraction of CO2 from the system. Although this is an active field of research, the design of such a combustor requires continued study of oxy-fuel combustion in high levels of CO2 diluent. With that objective in mind, laminar flame experiments were conducted for CH4-O2-CO2 mixtures at one atmosphere and room temperature, where the relative concentrations of O2 and CO2 in the oxidizer mixture were 34.0% and 66.0% by mole, respectively. These concentrations were chosen to ensure the flame would propagate quickly enough to overcome the effects of buoyancy, which were observed to become significant below laminar flame speeds of roughly 15 cm/s. A high-speed chemiluminescence imaging diagnostic was employed in place of the traditional schlieren technique. Laminar flame speed was measured from OH* emission at 306 nm for a full range of equivalence ratios, varying from 15.2 cm/s at 0.7 to 24.8 cm/s at stoichiometric. Additionally, images of OH* chemiluminescence of turbulent CH4-O2-CO2 flames and of quiescent, 5-atm CH4-O2-CO2 flames at stoichiometric concentration are also presented. These experiments provide useful data for validation of chemical kinetics models for oxy-methane combustion in a CO2 diluent, which can be applied to the modeling of oxy-methane combustion for supercritical CO2 power cycles.

Experimental Study on Laminar Flame Speeds and Markstein Length of Methane-Air Mixtures at Atmospheric Conditions

2014 ◽  
Vol 699 ◽  
pp. 714-719
Author(s):  
Alaeldeen Altag Yousif ◽  
Shaharin Anwar Sulaiman
Keyword(s):  
High Speed ◽  
Equivalence Ratio ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Ambient Pressure ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Atmospheric Conditions ◽  
Laminar Burning Velocity ◽  
Markstein Length

Accurate value of laminar flame speed is an important parameter of combustible mixtures. In this respect, experimental data are very useful for modeling improvement and validating chemical kinetic mechanisms. To achieve this, an experimental characterization on spherically expanding flames propagation of methane-air mixtures were carried out. Tests were conducted in constant volume cylindrical combustion chamber to measure stretched, unstretched laminar flame speed, laminar burning velocity, and flame stretch effect as quantified by the associated Markstein lengths. The mixtures of methane-air were ignited at extensive ranges of lean-to-rich equivalence ratios, under ambient pressure and temperature. This is achieved by high speed schlieren cine-photography for flames observation in the vessel. The results showed that the unstretched laminar burning velocity increased and the peak value of the unstretched laminar burning velocity shifted to the richer mixture side with the increase of equivalence ratio. The flame propagation speed showed different trends at different equivalence ratio for tested mixtures. It was found that the Markstein length was increased with the increase of equivalence ratio.

scholarly journals Impact of the laminar flame speed correlation on the results of a quasi-dimensional combustion model for Spark-Ignition engine

2018 ◽  
Vol 148 ◽  
pp. 631-638 ◽  
Author(s):  
L. Teodosio ◽  
F. Bozza ◽  
D. Tufano ◽  
P. Giannattasio ◽  
E. Distaso ◽  
...  
Keyword(s):  
Laminar Flame ◽  
Spark Ignition ◽  
Flame Speed ◽  
Spark Ignition Engine ◽  
Combustion Model ◽  
Laminar Flame Speed
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