Experimental studies of the effects of global equivalence ratio and CO2 dilution level on the OH* and CH* chemiluminescence in CH4/O2 diffusion flames

Fuel ◽  
2020 ◽  
Vol 278 ◽  
pp. 118307 ◽  
Author(s):  
Jiabao Yang ◽  
Yan Gong ◽  
Qinghua Guo ◽  
Huiwen Zhu ◽  
Fuchen Wang ◽  
...  
Keyword(s):  
Equivalence Ratio ◽  
Diffusion Flames ◽  
Experimental Studies ◽  
O2 Diffusion ◽  
Dilution Level

Investigation of Ducted Inverse Nonpremixed Flame Using Dynamic Systems Approach

2016 ◽  
Author(s):  
Uddalok Sen ◽  
Tryambak Gangopadhyay ◽  
Chandrachur Bhattacharya ◽  
Arpan Misra ◽  
Suman Karmakar ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Diffusion Flame ◽  
Equivalence Ratio ◽  
Systems Approach ◽  
Diffusion Flames ◽  
Duct Acoustics ◽  
Practical Applications ◽  
Inverse Diffusion ◽  
Inverse Diffusion Flame

Gas turbine combustion has a number of practical applications, including aviation engines, ocean vessels, and tanks. The various advantages of normal diffusion flames, such as increased flame stability and reduced susceptibility to dynamic instabilities, has made it the de facto industrial standard. However, high NOx emission and sooting from such flames is a major problem, particularly for heavier hydrocarbons fuels. In that regard, the inverse diffusion flame offers a feasible alternative; but the dynamic response of such a flame, particularly in ducted conditions — where the unsteady heat release interacts with the duct acoustics — is relatively less researched. In the present work, an experimental investigation of a laboratory-scale inverse diffusion flame has been carried out. The inverse diffusion flame is found in applications like rocket motors, gas turbine combustors, and furnaces. In the present study, inverse diffusion flame from a coaxial burner inside a quartz tube was studied. The position of the duct with respect to the flame was kept fixed, while the global equivalence ratio was varied by keeping the air flow rate constant and changing the fuel flow rate. Various tools of nonlinear dynamics such as phase space reconstruction and recurrence quantification have also been used for dynamic characterization of such flames. The results show that the dynamics of the flame strongly depends on the global equivalence ratio.

Numerical and experimental studies of the NO formation in laminar coflow diffusion flames on their transition to MILD combustion regime

2013 ◽  
Vol 160 (8) ◽  
pp. 1364-1372 ◽  
Author(s):  
A.V. Sepman ◽  
S.E. Abtahizadeh ◽  
A.V. Mokhov ◽  
J.A. van Oijen ◽  
H.B. Levinsky ◽  
...  
Keyword(s):  
Diffusion Flames ◽  
Experimental Studies ◽  
Combustion Regime ◽  
No Formation ◽  
Mild Combustion

Experimental Studies of the Micro-Structures of Opposed Flow Diffusion Flames: Methane

1997 ◽  
Vol 130 (1-6) ◽  
pp. 233-246 ◽  
Author(s):  
ANTONIO M. VINCITORE ◽  
SELIM M. SENKAN
Keyword(s):  
Diffusion Flames ◽  
Experimental Studies ◽  
Opposed Flow ◽  
Micro Structures

scholarly journals The effects of ring-shaped porous inert media on equivalence ratio oscillations in a self-excited thermoacoustic instability

2021 ◽  
pp. 175682772199177
Author(s):  
Cody Dowd ◽  
Joseph Meadows
Keyword(s):  
Equivalence Ratio ◽  
Fuel Injection ◽  
Dynamic Pressure ◽  
Experimental Studies ◽  
Feedback Mechanism ◽  
Abel Transformation ◽  
Thermoacoustic Instability ◽  
Thermoacoustic Instabilities ◽  
Spatially Resolved ◽  
Porous Inert Media

Gas turbine operation increasingly relies on lean premixed (LPM) combustion to reduce harmful emissions, which is susceptible to thermoacoustic instabilities. Most combustion systems are technically premixed and exhibit a degree of equivalence ratio inhomogeneity. Thermoacoustic pressure oscillations can couple with the heat release oscillations through the generation of equivalence ratio fluctuations at fuel injection sites, which are then convected to the flame front. Previous experimental studies have shown that porous inert media (PIM) can passively mitigate these instabilities by adding acoustic damping and by reducing the thermoacoustic feedback mechanism. To understand the role of PIM on these equivalence ratio oscillations, spatially resolved, phased averaged equivalence ratio fluctuations are measured using the ratio of OH*/CH* chemiluminescence. Spatial imaging of OH* or CH* radicals produce integrated line of sight intensity values and an Abel transformation is used to obtain spatially resolved values. Phase averaged images are synced with dynamic pressure measurements, and an axisymmetric atmospheric burner is used to study the effects of ring-shaped PIM on the spatially resolved equivalence ratio field with self-excited thermoacoustic instabilities. The results show that PIM significantly reduces these fluctuations, and the effects on the stability of the system are discussed.

Experimental studies of bluff-body stabilized LPG diffusion flames

Fuel ◽  
2009 ◽  
Vol 88 (3) ◽  
pp. 573-578 ◽  
Author(s):  
D.P. Mishra ◽  
D.Y. Kiran
Keyword(s):  
Bluff Body ◽  
Diffusion Flames ◽  
Experimental Studies

scholarly journals A bifurcation analysis of high-temperature ignition of H2−O2 diffusion flames

1994 ◽  
Vol 25 (1) ◽  
pp. 1529-1537 ◽  
Author(s):  
Antonio L. Sánchez ◽  
Amable Liñán ◽  
Forman A. Williams
Keyword(s):  
High Temperature ◽  
Bifurcation Analysis ◽  
Diffusion Flames ◽  
O2 Diffusion

Investigation on chemiluminescence and structure characteristics in CH4/O2 diffusion flames

2019 ◽  
Vol 102 ◽  
pp. 595-602 ◽  
Author(s):  
Huiwen Zhu ◽  
Chonghe Hu ◽  
Qinghua Guo ◽  
Yan Gong ◽  
Guangsuo Yu
Keyword(s):  
Diffusion Flames ◽  
Structure Characteristics ◽  
O2 Diffusion

The effect of global equivalence ratio and postflame temperature on the composition of emissions from laminar ethylene/air diffusion flames

1999 ◽  
Vol 118 (4) ◽  
pp. 521-536 ◽  
Author(s):  
Michael P. Tolocka ◽  
Peter B. Richardson ◽  
J. Houston Miller
Keyword(s):  
Equivalence Ratio ◽  
Diffusion Flames ◽  
Air Diffusion

scholarly journals Inlet Pressure Effects on Subatmospheric Flame Stabilization with an Optimum Size of a Cavity-Based Combustor

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Yakun Huang ◽  
Xiaomin He ◽  
Zhixin Zhu ◽  
Huanyu Zhu
Keyword(s):  
Equivalence Ratio ◽  
Experimental Studies ◽  
Flame Stabilization ◽  
Combined Cycle ◽  
Pressure Effects ◽  
Inlet Pressure ◽  
Flame Stability ◽  
Characteristic Time Scale ◽  
Optimum Size ◽  
Lean Blowout

Experimental studies are conducted to find an optimum size of the cavity flameholder, which is a new combustion concept of a turbine-based combined-cycle (TBCC) engine with an excellent flame stabilization. Besides, the effect of inlet pressure on the subatmospheric performance is investigated. The experimental results indicate that the increase of the cavity length improves the flame stability with an enlarged fuel/air mixture residence time, which suggests that the big length-height ratio in a proper range of the cavity with a stable dual-vortex should be chosen when designing the cavity-based combustor. In addition, the decrease in lean ignition and the lean blowout equivalence ratios can be attributed by either increase in the inlet pressure and temperature or decrease in the Mach number. The increase in inlet pressure will lead to a linear decrease in the lean blowout equivalence ratio with a slope of 0.66 per 0.1 MPa, whereas the lean ignition equivalence ratio has a rapid drop with the increase of pressure from 0.06 MPa to 0.08 MPa and reduces slowly with the growth of pressure in the range of 0.08 MPa to 0.1 MPa. The detailed analysis of the flow field indicates that the characteristic time-scale theory can ideally explain and predict the change of flame stability in the trapped vortex cavity.

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