scholarly journals Study of ignition delay time and generalization of auto-ignition for PRFs in a RCEM by means of natural chemiluminescence

2016 ◽  
Vol 111 ◽  
pp. 217-228 ◽  
Author(s):  
J.M. Desantes ◽  
J.M. García-Oliver ◽  
W. Vera-Tudela ◽  
D. López-Pintor ◽  
B. Schneider ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Auto Ignition

Ignition Studies of C1–C7 Natural Gas Blends at Gas-Turbine Relevant Conditions

2020 ◽  
Author(s):  
Amrit Bikram Sahu ◽  
A. Abd El-Sabor Mohamed ◽  
Snehasish Panigrahy ◽  
Gilles Bourque ◽  
Henry Curran
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Gas Mixtures ◽  
Auto Ignition ◽  
Wide Range ◽  
Detailed Kinetic Model ◽  
Sensitization Effect

Abstract New ignition delay time measurements of natural gas mixtures enriched with small amounts of n-hexane and n-heptane were performed in a rapid compression machine to interpret the sensitization effect of heavier hydrocarbons on auto-ignition at gas-turbine relevant conditions. The experimental data of natural gas mixtures containing alkanes from methane to n-heptane were carried out over a wide range of temperatures (840–1050 K), pressures (20–30 bar), and equivalence ratios (φ = 0.5 and 1.5). The experiments were complimented with numerical simulations using a detailed kinetic model developed to investigate the effect of n-hexane and n-heptane additions. Model predictions show that the addition of even small amounts (1–2%) of n-hexane and n-heptane can lead to increase in reactivity by ∼40–60 ms at compressed temperature (TC) = 700 K. The ignition delay time (IDT) of these mixtures decrease rapidly with an increase in concentration of up to 7.5% but becomes almost independent of the C6/C7 concentration beyond 10%. This sensitization effect of C6 and C7 is also found to be more pronounced in the temperature range 700–900 K compared to that at higher temperatures (> 900 K). The reason is attributed to the dependence of IDT primarily on H2O2(+M) ↔ 2ȮH(+M) at higher temperatures while the fuel dependent reactions such as H-atom abstraction, RȮ2 dissociation or Q.OOH + O2 reactions are less important compared to 700–900 K, where they are very important.

A Numerical Study on the Low Limit Auto-Ignition Temperature of Syngas and Modification of Chemical Kinetic Mechanism

2019 ◽  
Author(s):  
Seung Eon Jang ◽  
Jin Park ◽  
Sang Hyeon Han ◽  
Hong Jip Kim ◽  
Ki Sung Jung ◽  
...  
Keyword(s):  
Low Temperature ◽  
Temperature Region ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Numerical Results ◽  
Auto Ignition ◽  
Chemical Kinetic Mechanism

Abstract In this study, the auto ignition with low limit temperature of syngas has been numerically investigated using a 2-D numerical analysis. Previous study showed that auto ignition was observed at above 860 K in co-flow jet experiments using syngas and dry air. However, the auto ignition at this low temperature range could not be predicted with existing chemical mechanisms. Inconsistency of the auto ignition temperature between the experimental and numerical results is thought to be due to the inaccuracy of the chemical kinetic mechanism. The prediction of ignition delay time and sensitivity analysis for each chemical kinetic mechanism were performed to verify the reasons of the inconsistency between the experimental and numerical results. The results which were calculated using the various mechanisms showed significantly differences in the ignition delay time. In this study, we intend to analyze the reason of discrepancy to predict the auto ignition with low pressure and low temperature region of syngas and to improve the chemical kinetic mechanism. A sensitive analysis has been done to investigate the reaction steps which affected the ignition delay time significantly, and the reaction rate of the selected reaction step was modified. Through the modified chemical kinetic mechanism, we could identify the auto ignition in the low temperature region from the 2-D numerical results. Then CEMA (Chemical Explosive Mode Analysis) was used to validate the 2-D numerical analysis with modified chemical kinetic mechanism. From the validation, the calculated λexp, EI, and PI showed reasonable results, so we expect that the modified chemical kinetic mechanism can be used in various low temperature region.

Commissioning of a Test Rig for Auto-Ignition Delay Time Measurements on Kerosene Based Fuel Paper

2001 ◽  
Author(s):  
W. S. Cheung ◽  
J. R. Tilston
Keyword(s):  
Ignition Delay ◽  
Delay Time ◽  
Gas Turbines ◽  
Ignition Delay Time ◽  
Operating Experience ◽  
Ignition Process ◽  
Mean Flow ◽  
Test Rig ◽  
Auto Ignition ◽  
Technical Risks

A thorough understanding of the auto-ignition process is critical to the success of lean premixed prevapourised (LPP) combustors for future ultra-low NOx emissions gas turbines. A considerable amount of work has been done in the past on auto-ignition delay time (ADT) measurements for various aviation fuels and hydrocarbons. However, little was known about the influence of various possible fuel additives on ADT. A test rig was designed and built by DERA specifically for ADT measurements. It consisted of an injector housing and an instrumented duct where the ignition location could be monitored by fibre optic sensors. It was intended to acquire ADT measurements at 875K, 16bar and 40m/s of mean flow. The test rig and instrumentation were commissioned in January and February 2000. However, instrumentation inside the injector housing was damaged soon after the initial hot run as a result of overheating. Attempts were made to repair the damaged components and to identify the cause of overheating. Unfortunately, the damage to the components was extensive and the cause of overheating could not be diagnosed. In view of the technical risks involved, it was decided to stop further testing with this rig. Although ADT measurements could not be undertaken as planned, useful operating experience was gained from the tests conducted.

Low-temperature auto-ignition characteristics of NH3/diesel binary fuel: Ignition delay time measurement and kinetic analysis

Fuel ◽  
2020 ◽  
Vol 281 ◽  
pp. 118761 ◽  
Author(s):  
Yuan Feng ◽  
Jizhen Zhu ◽  
Yebing Mao ◽  
Mohsin Raza ◽  
Yong Qian ◽  
...  
Keyword(s):  
Low Temperature ◽  
Kinetic Analysis ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Time Measurement ◽  
Auto Ignition ◽  
Ignition Characteristics

Auto-Ignition of Gas Turbine Lubricating Oils in a Shock Tube Using Spray Injection

2021 ◽  
Author(s):  
Sean P. Cooper ◽  
Zachary K. Browne ◽  
Sulaiman A. Alturaifi ◽  
Olivier E. Mathieu ◽  
Eric Petersen
Keyword(s):  
Shock Tube ◽  
Gas Turbine ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Lubricating Oil ◽  
Fuel Injector ◽  
Lubricating Oils ◽  
Reflected Shock ◽  
Auto Ignition

Abstract In choosing the lubricating oil for a gas turbine system, properties such as viscosity, viscosity index, corrosion prevention, and thermal stability are chosen to optimize turbine longevity and efficiency. Another property that needs to be considered is the lubricant's reactivity, as the lubricant's ability to resist combustion during turbine operation is highly desirable. In evaluating a method to define reactivity, the extremely low vapor pressure of these lubricants makes conventional vaporization by heating impractical. To this end, a new experiment was designed and tested to evaluate the reactivity of lubricating oils using an existing shock-tube facility at Texas A&M University equipped with an automotive fuel injector. This experiment disperses a pre-measured amount of lubricant into a region of high-temperature air to study auto-ignition. To ensure proper dispersal, a laser extinction diagnostic was used to detect the lubricant particles behind the reflected shock as they are dispersed and vaporized. An OH* chemiluminescence diagnostic was used to determine ignition delay time. Using this method, various 32-, 36-, and 46-weight lubricants identified as widely used in the gas turbine industry were tested. Experiments were conducted in post-reflected shock conditions around 1370 K (2006 ºF) and 1.2 atm, where ignition delay time, peak OH* emission, and time-to-peak values were recorded and compared. Ignition was observed for all but one of the lubricants at these conditions, and mild to strong ignition was observed for the other lubricants with varying ignition delay times.

Auto-ignition characteristics of diesel fuel in an O2–CO2 mixture

2019 ◽  
Vol 43 (1) ◽  
pp. 1-12
Author(s):  
Yongfeng Liu ◽  
Tianpeng Zhao ◽  
Zhijun Li ◽  
Fang Wang ◽  
Shengzhuo Yao ◽  
...  
Keyword(s):  
Diesel Fuel ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Flame Temperature ◽  
Zone Model ◽  
Auto Ignition ◽  
Lift Off ◽  
Ignition Characteristics ◽  
Set Up

To study diesel fuel auto-ignition in an O2–CO2 mixture, a TZ (temperature zone) model is proposed. The effect of O2 and CO2 on reaction rate is considered. The relationship between temperature and ignition delay time is obtained. Different reduced mechanisms based on steady-state assumptions are applied in three temperature zones (T ≤ 800 K, 800 K < T ≤ 1100 K, T > 1100 K). The TZ model is coupled to KIVA-3V code for simulation calculations. To support the simulations, a constant-volume combustion bomb test bench is set up to visualize diesel fuel auto-ignition in air (21%O2–79%N2), a 53%O2–47%CO2 mixture, and a 61%O2–39%CO2 mixture. Ignition delay time and the flame image in these three conditions are compared and analyzed. Then the flame temperature contour and the flame lift-off length in a 53%O2–47%CO2 mixture and a 61%O2–39%CO2 mixture are analyzed. The results show that diesel fuel auto-ignition can be achieved in the tested O2–CO2 mixture. The TZ model can predict the auto-ignition characteristics of diesel fuel in a 53%O2–47%CO2 mixture and a 61%O2–39%CO2, with errors of 12% and 10%, respectively. In these two conditions, the ignition delay time and flame lift-off length are shorter than they are in air.

On the Influence of Fuel Stratification and Its Control on the Efficiency of the Shockless Explosion Combustion Cycle

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Tim S. Rähse ◽  
Panagiotis Stathopoulos ◽  
Jan-Simon Schäpel ◽  
Florian Arnold ◽  
Rudibert King
Keyword(s):  
Thermal Efficiency ◽  
Ignition Delay ◽  
Delay Time ◽  
Gas Turbines ◽  
Pressure Wave ◽  
Ignition Delay Time ◽  
Fuel Injection ◽  
Numerical Code ◽  
Fuel Stratification ◽  
Auto Ignition

Constant volume combustion (CVC) cycles for gas turbines are considered a very promising alternative to the conventional Joule cycle and its variations. The reason is the considerably higher thermal efficiency of these cycles, at least for their ideal versions. Shockless explosion combustion (SEC) is a method to approximate CVC. It is a cyclic process that consists of four stages, namely wave propagation, fuel injection, homogeneous auto-ignition, and exhaust. A pressure wave in the combustion chamber is used to realize the filling and exhaust phases. During the fuel injection stage, the equivalence ratio is controlled in such a way that the ignition delay time of the mixture matches its residence time in the chamber before auto-ignition. This means that the fuel injected first must have the longest ignition delay time, and thus forms the leanest mixture with air. By the same token, fuel injected last must form the richest mixture with air (assuming that a rich mixture leads to a small ignition delay). The total injection time is equal to the time that the wave needs to reach the open combustor end and return as a pressure wave to the closed end. Up to date, fuel stratification has been neglected in thermodynamic simulations of the SEC cycle. The current work presents its effect on the thermal efficiency of the cycle and on the exhaust conditions (pressure, temperature, and Mach number) of shockless explosion combustion chambers. This is done by integrating a fuel injection control algorithm in an existing computational fluid dynamics code. The capability of this algorithm to homogenize the auto-ignition process by improving the injection process has been demonstrated in past experimental studies of the SEC. The numerical code used for the simulation of the combustion process is based on the time-resolved 1D-Euler equations with source terms obtained from a detailed chemistry model.

On the Influence of Fuel Stratification and its Control on the Efficiency of the Shockless Explosion Combustion Cycle

2018 ◽  
Author(s):  
T. S. Rähse ◽  
P. Stathopoulos ◽  
J.-S. Schäpel ◽  
F. Arnold ◽  
R. King
Keyword(s):  
Thermal Efficiency ◽  
Ignition Delay ◽  
Delay Time ◽  
Pressure Wave ◽  
Ignition Delay Time ◽  
Fuel Injection ◽  
Constant Volume ◽  
Fuel Stratification ◽  
Auto Ignition ◽  
Constant Volume Combustion

Constant volume combustion cycles for gas turbines are considered a very promising alternative to the conventional Joule cycle and its variations. The reason is the considerably higher thermal efficiency of theses cycles, at least for their ideal versions. Shockless explosion combustion is a method to approximate constant volume combustion. It is a cyclic process that consists of four stages, namely wave propagation, fuel injection, homogeneous auto-ignition and exhaust. A pressure wave in the combustion chamber is used to realize the filling and exhaust phases. During the fuel injection stage, the equivalence ratio is controlled in such a way that the ignition delay time of the mixture matches its residence time in the chamber before self ignition. This means that the fuel injected first must have the longest ignition delay time and thus forms the leanest mixture with air. By the same token, fuel injected last must form the richest mixture with air (assuming that a rich mixture leads to a small ignition delay). The total injection time is equal to the time that the wave needs to reach the open combustor end and return as a pressure wave to the closed end. Up to date, fuel stratification has been neglected in thermodynamic simulations of the SEC cycle. The current work presents its effect on the thermal efficiency of the cycle and on the exhaust conditions (pressure, temperature and Mach number) of shockless explosion combustion chambers. This is done by integrating a fuel injection control algorithm in an existing CFD code. The capability of this algorithm to homogenize the auto-ignition process by improving the injection process has been demonstrated in past experimental studies of the SEC. The numerical code used for the simulation of the combustion process is based on the time-resolved 1D-Euler equations with source terms obtained from a detailed chemistry model.

Auto-Ignition of Gas Turbine Lubricating Oils in a Shock Tube Using Spray Injection

2020 ◽  
Author(s):  
Sean P. Cooper ◽  
Zachary K. Browne ◽  
Sulaiman A. Alturaifi ◽  
Olivier Mathieu ◽  
Eric L. Petersen
Keyword(s):  
Shock Tube ◽  
Gas Turbine ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Lubricating Oil ◽  
Fuel Injector ◽  
Lubricating Oils ◽  
Reflected Shock ◽  
Auto Ignition

Abstract In choosing the lubricating oil for a gas turbine system, properties such as viscosity, viscosity index, corrosion prevention, and thermal stability are chosen to optimize turbine longevity and efficiency. Another property that needs to be considered is the lubricant’s reactivity, as the lubricant’s ability to resist combustion during turbine operation is highly desirable. In evaluating a method to define reactivity, the extremely low vapor pressure of these lubricants makes conventional vaporization by heating impractical due to the high temperatures and fuel cracking as well as issues with preferential vaporization. To this end, a new experiment was designed and tested to evaluate the reactivity of lubricating oils using an existing shock-tube facility at Texas A&M University equipped with an automotive fuel injector. This experiment disperses a pre-measured amount of lubricant into a region of high-temperature air to study auto-ignition. To ensure proper dispersal, a laser extinction diagnostic was used to measure the lubricant particles behind the reflected shock as they are dispersed and vaporized. An OH* chemiluminescence diagnostic measuring light emitted during combustion at around 306 nm was used to determine ignition delay time. Pressure was also measured at the sidewall and endwall positions for test repeatability and exothermicity of the experiments. The methods were validated by conducting experiments with ethanol and comparing the results to previous heated shock-tube experiments conducted in the same facility. Using this method, various 32-, 36-, and 46-weight lubricants identified as widely used in the gas turbine industry were tested. Experiments were conducted in post-reflected shock conditions around 1370K (2006 °F) and 1.2 atm, where ignition delay time, peak OH* emission and time-to-peak values were recorded and compared. Ignition was observed for all but one of the lubricants at these conditions, and mild to strong ignition was observed for the other lubricants with varying ignition delay times.

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