Pressure-Based Ignition Delay Times of Non-Premixed Turbulent Jet Flames Using Various Turbulence Models

2016 ◽  
Author(s):  
O. Samimi Abianeh ◽  
M. Levins ◽  
C. P. Chen
Keyword(s):  
Experimental Data ◽  
Combustion Chamber ◽  
Ignition Delay ◽  
Pressure Rise ◽  
Turbulence Models ◽  
Dynamic Structure ◽  
Chamber Pressure ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Lift Off

Pressure-based ignition delay times of turbulent spray combustion of n-dodecane fuel were studied using two turbulence models: Large Eddy Simulations (LES) of turbulence and Reynolds Averaged Navier Stokes (RANS). Standard RNG k-ε and Dynamic Structure models were utilized for RANS and LES turbulence modeling respectively. The simulated combustion chamber pressure rise, lift-off length, liquid penetration, and vapor penetration were compared with experimental data. The combustion chamber initial gas temperatures ranged from 850 K to 1200 K at an initial gas density of 22.8 kg/m3. A recently developed skeletal mechanism of n-dodecane with 85 species was utilized in the current work. The pressure-based ignition delay times using the Dynamic Structure turbulence model were well matched with experimental data, but the simulated pressure-based ignition delay time was over-predicted using RNG k-ε model at initial combustion chamber temperature of 850 K. The flame lift-off length, spray structure and species production and consumption histories were also investigated using different models. Both turbulence models show similar spray lift-off length at time of luminosity-based ignition delay at various combustion chamber temperatures.

Study of Turbulent Spray Combustion of N-Dodecane Fuel

2015 ◽  
Author(s):  
O. Samimi Abianeh
Keyword(s):  
Combustion Chamber ◽  
Ignition Delay ◽  
Pressure Rise ◽  
Chamber Pressure ◽  
Spray Combustion ◽  
Turbulent Spray Combustion ◽  
Temperature Combustion ◽  
Time Histories ◽  
Turbulent Spray ◽  
Lift Off

Turbulent spray combustion of n-dodecane fuel was studied numerically in current paper. The ignition delay, lift-off length, combustion chamber pressure rise, fuel penetration and vapor mass fraction were compared with experimental data. n-Dodecane kinetic model was studied by using a recently developed mechanism. The combustion chamber pressure rise was modeled and compared with experiments; the result was corrected for speed-of-sound to find the ignition delay timing in comparison with pressure-based ignition delay measurement. Species time histories and reaction paths at low and high temperature combustion are modeled and studied at two conditions, 900 K and 1200 K combustion chamber temperatures. The modeled species mass histories were discussed to define the first-stage and total ignition delay timings. Among all of the studied species in this work, including OH, Hydroperoxyalkyl mass history can be utilized to determine the exact timing of luminosity-based ignition delay. Moreover, n-dodecane vapor penetration can be used to determine the luminosity-based ignition delay.

Investigation of Chemical Kinetic Model for Hypergolic Propellant of Monomethylhydrazine and Nitrogen Tetroxide

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
Hu Hong-bo ◽  
Chen Hong-yu ◽  
Yan Yu ◽  
Zhang Feng ◽  
Yin Ji-Hui ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Flame Temperature ◽  
Chemical Kinetic ◽  
Chemical Mechanism ◽  
Chamber Pressure ◽  
Nitrogen Tetroxide ◽  
Combustion Flame ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Calculation Results

Abstract Hypergolic bipropellant of monomethylhydrazine (MMH) and nitrogen tetroxide (NTO) is extensively used in spacecraft propulsion applications and rocket engines. But studies on the chemical kinetic mechanism of MMH/NTO are limited. So, in this study by integrating the submechanisms of MMH decomposition, NTO thermal decomposition, MMH/NTO and intermediates, and small hydrocarbons, the comprehensive chemical mechanism of MMH/NTO bipropellant is proposed. The present chemical mechanism consists of 72 species and 406 elementary reactions. In two respects of ignition delay times and combustion flame temperatures, the present model has been validated against the theoretical calculation results and also compared with other kinetic models in the literature. The validations show that the predicted ignition delay times by the present kinetic model are highly consistent with the theoretical data and well describe the pressure-dependent characteristic. For combustion flame temperature, the present model also exhibits better predictions to the theoretical calculation results, which are also the same as the predictions by the MMH-RFNA model. Furthermore, the influences of initial temperature, chamber pressure, and NTO/HHM mass ratio (O/F) on the ignition delay time and combustion flame temperature are investigated. The auto-ignition behavior of MMH/NTO propellant is sensitive to initial temperature and chamber pressure, and the combustion flame temperature is more sensitive to the O/F. This study provides a detail chemical kinetics model for further mechanism simplification and combustion numerical simulation.

High Pressure Ignition Delay Times Measurements and Comparison of the Performance of Several Oxy-Syngas Mechanisms Under High CO2 Dilution

2018 ◽  
Author(s):  
Samuel Barak ◽  
Erik Ninnemann ◽  
Sneha Neupane ◽  
Frank Barnes ◽  
Jayanta Kapat ◽  
...  
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Ignition Delay ◽  
Current Data ◽  
High Co2 ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Syngas Combustion ◽  
Data Points

In this study, syngas combustion was investigated behind reflected shock waves in CO2 bath gas to measure ignition delay times and to probe the effects of CO2 dilution. New syngas data were taken between pressures of 34.58–45.50 atm and temperatures of 1113–1275K. This study provides experimental data for syngas combustion in CO2 diluted environments: ignition studies in a shock tube (59 data points in 10 datasets). In total, these mixtures covered a range of temperatures T, pressures P, equivalence ratios φ, H2/CO ratio θ, and CO2 diluent concentrations. Multiple syngas combustion mechanisms exist in the literature for modelling ignition delay times and their performance can be assessed against data collected here. In total, twelve mechanisms were tested and presented in this work. All mechanisms need improvements at higher pressures for accurately predicting the measured ignition delay times. At lower pressures, some of the models agreed relatively well with the data. Some mechanisms predicted ignition delay times which were 2 orders of magnitudes different from the measurements. This suggests there is behavior that has not been fully understood on the kinetic models and are inaccurate in predicting CO2 diluted environments for syngas combustion. To the best of our knowledge, current data are the first syngas ignition delay times measurements close to 50 atm under highly CO2 diluted (85% per vol.) conditions.

A Study on Fundamental Combustion Properties of Oxymethylene Ether-2

2021 ◽  
Author(s):  
John N. Ngugi ◽  
Sandra Richter ◽  
Marina Braun-Unkhoff ◽  
Clemens Naumann ◽  
Markus Köhler ◽  
...  
Keyword(s):  
Experimental Data ◽  
Reaction Mechanisms ◽  
Ignition Delay ◽  
Laminar Flame ◽  
Cone Angle ◽  
Sensitivity Analyses ◽  
Chain Reactions ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times

Abstract Oxymethylene ethers (OMEn, n = 1–5) are a promising class of synthetic fuels that have the potential to be used as additives or substitutes to diesel in compression ignition engines. A comprehensive understanding of their combustion properties is required for their safe and efficient utilization. In this study, the results of a combined experimental and modeling work on oxidation of OME2 are reported: (i) Ignition delay time measurements of stoichiometric OME2 / synthetic air mixtures diluted 1:5 with nitrogen using the shock tube method at pressures of 1, 4, and 16 bar, and (ii) laminar flame speeds of OME2 / air mixtures using the cone angle method at ambient and elevated pressures of 3 and 6 bar. The experimental data sets obtained have been used for validation of a detailed reaction mechanisms of OME2. The results of ignition delay times showed that OME2 exhibits a two-stage ignition in the lower temperature region. There is a good match of the measured data compared to the predicted ones using three reaction mechanisms from the literature. The mechanism from Cai et al. (2020) best predicted the temperature and pressure dependence of ignition delay times. For laminar flame speeds, the experimental data were well matched by the mechanism from Ren et al. (2019) at p = 1, 3, and 6 bar and for all equivalence ratios considered. From sensitivity analyses calculations, it was observed that chain reactions involving small radicals, i.e., H, O, OH, HO2, and CH3 control the oxidation of OME2. The comparison of the results of this work and our previous work (Ngugi et al. (2021)) on OME1 show that these two fuels have similar oxidation pathways. The results obtained in this work will contribute to a better understanding of the combustion of oxymethylene ethers, and thus, to the design and optimization of burners and engines as well.

Auto Ignition Study of Methane and Bio Alcohol Fuel Blends

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Xuan Zheng ◽  
Shirin Jouzdani ◽  
Benjamin Akih-Kumgeh
Keyword(s):  
Experimental Data ◽  
Kinetic Models ◽  
Ignition Delay ◽  
Chemical Kinetic ◽  
Dual Fuel ◽  
Fuel Blends ◽  
Ignition Delay Times ◽  
Auto Ignition ◽  
Alcohol Fuel ◽  
Delay Times

Abstract Methane (CH4) and bio alcohols have different ignition properties. These have been extensively studied and the resulting experimental data have been used to validate chemical kinetic models. Methane is the main component of natural gas, which is of interest because of its relative availability and lower emissions compared to other hydrocarbon fuels. Given growing interest in fuel-flexible systems, there can be situations in which the combustion properties of natural gas need to be modified by adding biofuels such as bio alcohols. This can occur in dual-fuel internal combustion engines or gas turbines with dual-fuel capabilities. The combustion behavior of such blends can be understood by studying the auto ignition properties in fundamental combustion experiments. Studies of the ignition of such blends are very limited in the literature. In this work, the auto ignition of methane and bio alcohol fuel blends is investigated using a shock tube facility. The chosen bio alcohols are ethanol (C2H5OH) and n-propanol (NC3H7OH). Experiments are carried out at 3 atm and 10 atm for stoichiometric and lean mixtures of fuel, oxygen, and argon. The ignition delay times of the pure fuels are first established at conditions of constant oxygen concentration and comparable pressures. The ignition delay times of blends with 50% methane are then measured. The pyrolysis kinetics of the blends is further explored by measuring CO formation during pyrolysis of the alcohol and methane–alcohol blends. The resulting experimental data are compared with the predictions of selected chemical kinetic models to establish the ability of these models to predict the disproportionate enhancement of methane ignition by the added alcohol.

Auto Ignition Study of Methane and Bio Alcohol Fuel Blends

2019 ◽  
Author(s):  
Xuan Zheng ◽  
Shirin Jouzdani ◽  
Benjamin Akih-Kumgeh
Keyword(s):  
Experimental Data ◽  
Kinetic Models ◽  
Ignition Delay ◽  
Chemical Kinetic ◽  
Dual Fuel ◽  
Fuel Blends ◽  
Ignition Delay Times ◽  
Auto Ignition ◽  
Alcohol Fuel ◽  
Delay Times

Abstract Methane (CH4) and bio alcohols have different ignition properties. These have been extensively studied and the resulting experimental data have been used to validate chemical kinetic models. Methane is the main component of natural gas, which is of interest because of its relative availability and lower emissions compared to other hydrocarbon fuels. Given growing interest in fuel-flexible systems, there can be situations in which the combustion properties of natural gas need to be modified by adding biofuels, such as bio alcohols. This can occur in dual fuel internal combustion engines or gas turbines with dual fuel capabilities. The combustion behavior of such blends can be understood by studying the auto ignition properties in fundamental combustion experiments. Studies of the ignition of such blends are very limited in the literature. In this work, the auto ignition of methane and bio alcohol fuel blends is investigated using a shock tube facility. The chosen bio alcohols are ethanol (C2H5OH) and n-propanol (NC3H7OH). Experiments are carried out at 3 atm and 10 atm for stoichiometric and lean mixtures of fuel, oxygen, and argon. The ignition delay times of the pure fuels are first established at conditions of constant oxygen concentration and comparable pressures. The ignition delay times of blends with 50% methane are then measured. The pyrolysis kinetics of the blends is further explored by measuring CO formation during pyrolysis of the alcohol and methane-alcohol blends. The resulting experimental data are compared with the predictions of selected chemical kinetic models to establish the ability of these models to predict the disproportionate enhancement of methane ignition by the added alcohol.

High-Pressure Oxy-Syngas Ignition Delay Times With CO2 Dilution: Shock Tube Measurements and Comparison of the Performance of Kinetic Mechanisms

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Samuel Barak ◽  
Erik Ninnemann ◽  
Sneha Neupane ◽  
Frank Barnes ◽  
Jayanta Kapat ◽  
...  
Keyword(s):  
Experimental Data ◽  
Shock Tube ◽  
Ignition Delay ◽  
Current Data ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Syngas Combustion ◽  
Kinetic Mechanisms ◽  
Data Points

In this study, syngas combustion was investigated behind reflected shock waves in CO2 bath gas to measure ignition delay times (IDT) and to probe the effects of CO2 dilution. New syngas data were taken between pressures of 34.58–45.50 atm and temperatures of 1113–1275 K. This study provides experimental data for syngas combustion in CO2 diluted environments: ignition studies in a shock tube (59 data points in 10 datasets). In total, these mixtures covered a range of temperatures T, pressures P, equivalence ratios φ, H2/CO ratio θ, and CO2 diluent concentrations. Multiple syngas combustion mechanisms exist in the literature for modeling IDTs and their performance can be assessed against data collected here. In total, twelve mechanisms were tested and presented in this work. All mechanisms need improvements at higher pressures for accurately predicting the measured IDTs. At lower pressures, some of the models agreed relatively well with the data. Some mechanisms predicted IDTs which were two orders of magnitudes different from the measurements. This suggests that there is behavior that has not been fully understood on the kinetic models and is inaccurate in predicting CO2 diluted environments for syngas combustion. To the best of our knowledge, current data are the first syngas IDTs measurements close to 50 atm under highly CO2 diluted (85% per vol.) conditions.

An Experimental and Modelling Study of Ignition Delays in Shock-Heated Ethane-Oxygen-Argon Mixtures Inhibited by 2H-Heptafluoropropane

2001 ◽  
Vol 215 (8) ◽  
Author(s):  
K. Ikeda ◽  
J.C. Mackie
Keyword(s):  
Shock Waves ◽  
Ignition Delay ◽  
Kinetic Modelling ◽  
Pressure Rise ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Modelling Study

Ignition delay times have been measured behind reflected shock waves in ethane-oxygen-argon mixtures at temperatures between 1150 and 1500 K and pre-ignition pressures between 10 and 14 atm. Delay times have been measured both by pressure rise and OH absorption at 307 nm. Kinetic modelling of the ignition delays has been made using the GRIMech 3.0 mechanism which with addition of several reactions involving HO

scholarly journals Comparison of detailed reaction mechanisms for homogeneous ammonia combustion

2020 ◽  
Vol 234 (7-9) ◽  
pp. 1329-1357 ◽  
Author(s):  
László Kawka ◽  
Gergely Juhász ◽  
Máté Papp ◽  
Tibor Nagy ◽  
István Gy. Zsély ◽  
...  
Keyword(s):  
Experimental Data ◽  
Ignition Delay ◽  
Error Function ◽  
Data Format ◽  
Flow Reactors ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Data Points ◽  
Experimental Errors ◽  
Error Estimations

AbstractAmmonia is a potential fuel for the storage of thermal energy. Experimental data were collected for homogeneous ammonia combustion: ignition delay times measured in shock tubes (247 data points in 28 datasets from four publications) and species concentration measurements from flow reactors (194/22/4). The measurements cover wide ranges of temperature T, pressure p, equivalence ratio φ and dilution. The experimental data were encoded in ReSpecTh Kinetics Data Format version 2.2 XML files. The standard deviations of the experimental datasets used were determined based on the experimental errors reported in the publications and also on error estimations obtained using program MinimalSplineFit. Simulations were carried out with eight recently published mechanisms at the conditions of these experiments using the Optima++ framework code, and the FlameMaster and OpenSmoke++ solver packages. The performance of the mechanisms was compared using a sum-of-square error function to quantify the agreement between the simulations and the experimental data. Ignition delay times were well reproduced by five mechanisms, the best ones were Glarborg-2018 and Shrestha-2018. None of the mechanisms were able to reproduce well the profiles of NO, N2O and NH3 concentrations measured in flow reactors.

A Study On Fundamental Combustion Properties of Oxymethylene Ether-2

2021 ◽  
Author(s):  
John Mburu Ngugi ◽  
Sandra Richter ◽  
Marina Braun-Unkhoff ◽  
Clemens Naumann ◽  
Markus Köhler ◽  
...  
Keyword(s):  
Experimental Data ◽  
Ignition Delay ◽  
Laminar Flame ◽  
Cone Angle ◽  
Sensitivity Analyses ◽  
Chain Reactions ◽  
Design And Optimization ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times

Abstract Oxymethylene ethers (OMEn, n=1-5) are a promising class of synthetic fuels that have the potential to be used as diesel additives or substitutes. A comprehensive understanding of their combustion properties is required for their safe and efficient utilization. In this study, a combined experimental and modeling work on oxidation of OME2 is reported: (i) Ignition delay time measurements of stoichiometric OME2 / synthetic air mixtures diluted 1:5 with nitrogen using the shock tube method at pressures of 1, 4, and 16 bar, and (ii) laminar flame speeds of OME2 / air mixtures using the cone angle method at pressures of 1, 3 and 6 bar. The experimental data obtained have been used for validation of three detailed reaction mechanisms of OME2. The results of ignition delay times showed that OME2 exhibits a two-stage ignition in the lower temperature region. The mechanism from Cai et al. (2020) best predicted the temperature and pressure dependence of ignition delay times. For laminar flame speeds, the experimental data were well matched by the mechanism from Ren et al. (2019) for all the conditions of pressures and equivalence ratios considered. From sensitivity analyses, it was observed that chain reactions involving small radicals, i.e., H, O, OH, HO2, and CH3 control the oxidation of OME2. The results obtained in this work will contribute to a better understanding of the combustion of oxymethylene ethers, and thus, to the design and optimization of burners and engines as well.

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