Visualization Research of Nonpremixed Biodiesel/Air Jet Flames Unstable Combustion Process

Fuel Cells ◽  
2020 ◽  
Author(s):  
F. Liu
Keyword(s):  
Combustion Process ◽  
Jet Flames ◽  
Air Jet ◽  
Unstable Combustion

Study of high-pressure air jet controlled compression ignition with compound thermodynamic cycle for combustion and emission formation process

2020 ◽  
pp. 146808742096933
Author(s):  
Xiangyu Meng ◽  
Sicheng Liu ◽  
Jingchen Cui ◽  
Jiangping Tian ◽  
Wuqiang Long ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Low Temperature ◽  
Formation Process ◽  
Combustion Process ◽  
Thermodynamic Cycle ◽  
Compression Ignition ◽  
Temperature Reaction ◽  
Air Jet ◽  
High Temperature Reaction

A novel method called high-pressure air (HPA) jet controlled compression ignition (JCCI) based on the compound thermodynamic cycle was investigated in this work. The combustion process of premixed mixture can be controlled flexibly by the high-pressure air jet compression, and it characterizes the intensified low-temperature reaction and two-stage high-temperature reaction. The three-dimensional (3D) computational fluid dynamics (CFD) numerical simulation was employed to study the emission formation process and mechanism, and the effects of high-pressure air jet temperature and duration on emissions were also investigated. The simulation results showed that the NOx formation is mainly affected by the first-stage high-temperature reaction due to the higher reaction temperature. Overall, this combustion mode can obtain ultra-low NOx emission. The second-stage high-temperature reaction plays an important role in the CO and THC formation caused by the mixing effect of the high-pressure air and original in-cylinder mixture. The increasing air jet temperature leads to a larger high-temperature in-cylinder region and more fuel in the first-stage reaction, and therefore resulting in higher NOx emission. However, the increasing air jet temperature can significantly reduce the CO and THC emissions. For the air jet duration comparisons, both too short and too long air jet durations could induce higher NOx emission. A higher air jet duration would result in higher CO emission due to the more high-pressure air jet with relatively low temperature.

Influence of Burner Material, Tip Temperature, and Geometrical Flame Configuration on Flashback Propensity of H2-Air Jet Flames

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Zhixuan Duan ◽  
Brendan Shaffer ◽  
Vincent McDonell ◽  
Georg Baumgartner ◽  
Thomas Sattelmayer
Keyword(s):  
Jet Flames ◽  
Comprehensive Overview ◽  
High Hydrogen ◽  
Jet Flame ◽  
Practical Applications ◽  
Geometric Configurations ◽  
Air Jet ◽  
Low Emission ◽  
Flame Burner ◽  
Negative Impacts

Flashback is a key operability issue for low emission premixed combustion systems operated on high hydrogen content fuels. Previous work investigated fuel composition impacts on flashback propensity and found that burner tip temperature was important in correlating flashback data in premixed jet flames. An enclosure around the jet flame was found to enhance the flame–burner rim interaction. The present study further addresses these issues using a jet burner with various geometric configurations and interchangeable materials. Systematic studies addressing the quantitative influence of various parameters such as tip temperature, burner material, enclosure size, and burner diameter on flashback propensity were carried out. A comprehensive overview of the flashback limits for all conditions tested in the current study as well as those published previously is given. The collective results indicate that the burner materials, tip temperature, and flame confinement play significant roles for flashback propensity and thus help explain previous scatter in flashback data. Furthermore, the present work indicates that the upstream flame propagation during flashback is affected by the burner material. The material with lower thermal conductivity yields larger flashback propensity but slower flame regression inside the tube. These observations can be potentially exploited to minimize the negative impacts of flashback in practical applications.

Large Eddy Simulation of Pilot Stabilized Turbulent Premixed CH4+Air Jet Flames

2018 ◽  
Author(s):  
Veeraraghava Raju Hasti ◽  
Gaurav Kumar ◽  
Shuaishuai Liu ◽  
Robert P. Lucht ◽  
Jay P. Gore
Keyword(s):  
Large Eddy Simulation ◽  
Jet Flames ◽  
Eddy Simulation ◽  
Air Jet ◽  
Large Eddy ◽  
Turbulent Premixed

Experimental Investigation of Low Emission Liquid Fuelled Reverse Cross Flow Combustor

2017 ◽  
Author(s):  
Preetam Sharma ◽  
Vaibhav Arghode
Keyword(s):  
Experimental Investigation ◽  
Reaction Zone ◽  
Liquid Fuel ◽  
Alternative Fuels ◽  
Reverse Flow ◽  
Hot Spot ◽  
Combustion Process ◽  
Cross Flow ◽  
Air Jet ◽  
Low Emission

This study deals with an experimental investigation of a low emission liquid fuelled (ethanol) reverse cross-flow combustor. This investigation is carried out to cater to the need of burning liquid fuels (including alternative fuels) with minimum emissions in gas turbine engines used for both aircraft and land based power generation applications using modern combustion technologies. In the present combustor design, the air inlet and the exhaust ports are located on the same side (and hence the name reverse-flow) whereas the liquid fuel is injected directly into the strong cross-flow of the air using a small diameter round tube to aid fuel atomization. Hence, a conventional atomization system is absent in the investigated combustor. The reverse-flow configuration allows effective internal product gas recirculation to facilitate the preheating and dilution of the oxidizer stream and stabilization of a distributed reaction zone. This apparently suppresses near stoichiometric reactions and hot spot regions resulting in low pollutant (NOx and CO) emissions. In the present case, the heat load is varied (keeping a constant air flow rate) from 3.125 kW to 6.25 kW which results in the thermal intensity variation from 19 MW/m3-atm to 39 MW/m3-atm. Two different tubes with internal diameters (dfuel) of 0.5 mm and 0.8 mm are used for injection of liquid fuel into the cross flow of air. The combustor was also tested in premixed-prevaporized (PP) mode with ethanol for benchmarking. The combustion process was found to be stable with NOx emissions of 1.6 ppm (premixed-prevaporized), 8 ppm (dfuel = 0.5 mm), 9 ppm (dfuel = 0.8 mm). The CO emissions were 5 ppm (premixed-prevaporized), ∼100 ppm (dfuel = 0.5, 0.8 mm), at atmospheric pressure operation (corrected to 15% O2) and ϕ = 0.7, Tadiabatic ∼1830 K. Reaction zone positioning inside the combustor was investigated using OH* chemiluminescence imaging and global flame pictures, and the same was found to be located in the vicinity of the air jet.

scholarly journals PIV and OH PLIF study of impinging propane-air jet-flames

2016 ◽  
Vol 754 ◽  
pp. 072001 ◽  
Author(s):  
Z D Kravtsov ◽  
Z D Tolstoguzov ◽  
L M Chikishev ◽  
V M Dulin
Keyword(s):  
Jet Flames ◽  
Air Jet

scholarly journals Characterization of Periodic, Quasiperiodic, and Chaotic States in Nonpremixed Biodiesel/Air Jet Flames

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
Jianxin Xu ◽  
Hua Wang ◽  
Hui Fang
Keyword(s):  
Image Analysis ◽  
Maximum Lyapunov Exponent ◽  
Recurrence Plots ◽  
Jet Flames ◽  
Fuel Flow ◽  
Air Jet ◽  
Analysis Technique ◽  
Tip Position ◽  
Relative Change

Characterization for nonpremixed biodiesel/air jet flames instability is investigated by the 0-1 test for chaos and recurrence plots. Test conditions involve biodiesel from Jatropha curcas. L-fueled flames have inlet oil pressure of 0.2–0.6 MPa, fuel flow rates (Q1) of 15–30 kg/h, and combustion air flow rate (Q2) of 150–750 m3/h. This method is based on image analysis and nonlinear dynamics. Structures of flame are analyzed using an image analysis technique to extract position series which are representative of the relative change in temperature of combustion chamber. Compared with the method of maximum Lyapunov exponent, the 0-1 test succeeds in detecting the presence of regular and chaotic components in flame position series. Periodic and quasiperiodic characteristics are obtained by the Poincaré sections. A common characteristic of regular nonpremixed flame tip position series is detected by recurrence plots. Experimental results show that these flame oscillations follow a route to chaos via periodic and quasiperiodic states.

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