Effect of Switching Methane/Oxygen Reactants in a Coaxial Injector on the Stability of Non-Premixed Flames

2008 ◽  
Vol 180 (3) ◽  
pp. 401-417 ◽  
Author(s):  
Jeffrey D. Moore ◽  
Kenneth K. Kuo
Keyword(s):  
Premixed Flames ◽  
The Stability ◽  
Coaxial Injector

Investigation of Subcritical Instability in Ducted Premixed Flames

2011 ◽  
Author(s):  
Lipika Kabiraj ◽  
R. I. Sujith
Keyword(s):  
Experimental Investigation ◽  
Dynamical Behavior ◽  
Premixed Flames ◽  
Stability Diagram ◽  
Laminar Flames ◽  
Subcritical Instability ◽  
Bistable Region ◽  
Acoustic Forcing ◽  
The Stability

An experimental investigation of the bistable region of instability in a thermoacoustic system comprising of ducted, pre-mixed laminar flames has been performed. The stability diagram of the system is obtained and the bistable region for a range of flame locations at different fuel-air mixture equivalence ratios is identified. Subsequently, threshold amplitudes for triggering instability in the system using sinusoidal acoustic forcing, introduced externally, is obtained. It is observed that depending on how close the system is to the Hopf point and the nature of oscillations at the Hopf point, the triggered oscillations can exhibit different dynamical behavior.

Experimental Study of Non-Premixed Flames of Liquefied Petroleum Gas and Air in Cross-Flow and the Effects of Fuel Properties on Flame Stability

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
S. Muthu Kumaran ◽  
Vasudevan Raghavan
Keyword(s):  
Premixed Flames ◽  
Cross Flow ◽  
Operating Conditions ◽  
Fuel Properties ◽  
Jet Flows ◽  
Flame Stability ◽  
Bluff Bodies ◽  
Liquefied Petroleum Gas ◽  
Air Jet ◽  
The Stability

Abstract Stability of flames are affected by fuel properties, geometry of the burner and operating conditions. In this experimental work, first the characteristics of non-premixed flames of Liquefied Petroleum Gas (LPG) and air in cross-flow configuration, where air jet flows perpendicular to the fuel stream, are studied experimentally. Flame transition and stability regimes of non-premixed flames of LPG and air, in a cross-flow burner without and with obstacles, are determined by systematically varying the fuel and air flow rates. Obstacles such as backward facing step and cylindrical bluff bodies are considered. Subsequently, the effects of fuel properties on the stability of flames are analyzed, Flame stability regimes of natural gas (methane) and biogas (methane and carbon-dioxide), measured from a similar burner are available in literature. These have been compared with the stability of LPG flames in terms of power rating of the burner and global equivalence ratio (defined for non-premixed flames).

On the Stability of Near-Equidiffusional Strained Premixed Flames

1990 ◽  
Vol 69 (4-6) ◽  
pp. 85-97 ◽  
Author(s):  
YEONGDAE KIM ◽  
MOSHE MATALON
Keyword(s):  
Premixed Flames ◽  
The Stability

Effect of Equivalence Ratio and Burner Geometry on the Characteristics of Laminar Premixed Flames at Moderate Coflow

2004 ◽  
Author(s):  
P. Hariharan ◽  
S. R. Gollahalli
Keyword(s):  
Aspect Ratio ◽  
Equivalence Ratio ◽  
Premixed Flames ◽  
Combustion Efficiency ◽  
Flame Height ◽  
No Production ◽  
Air Velocity ◽  
Burner Flame ◽  
Jet Velocity ◽  
The Stability

The importance of studying laminar premixed flames lies in applications such as gas ranges and ovens, heating appliances and Bunsen burners. With the current demand for large amounts of economical, clean power, there is a need for research in increasing the combustion efficiency. Laminar premixed Propane/Hydrogen/Air flames with 3 m/s coflow and without coflow, with a variation of jet equivalence ratio (JEQ) from 0.5 to 4 for 20 m/s jet velocity, have been studied experimentally to determine the interactions of burner geometry of premixed flames and coflow. Two different burner geometries (circular burner, and 3:1 aspect ratio (AR) burners) were used in the experiments. The stability tests indicated that for 20 m/s jet velocity both at quiescent and coflow conditions the circular burner was more stable than the 3:1AR elliptical burner. Flame height studies indicated that circular burner flames were taller than the 3:1AR elliptical burner flames. However, there was a reduction in flame height when coflow air velocity of 3 m/s was introduced. Temperature profile indicated a higher peak temperature for circular burners followed by elliptical burner, both at quiescent and coflow conditions. The introduction of moderate coflow showed a decrease in NO production rate. In order to explain the structure of the flame in detail and various mechanisms that lead to the explanation of global flame characteristics, inflame concentration measurements were taken in near burner (25% of flame height), mid burner (50% of flame height) and far burner (75% of flame height) regions of the flame.

Thermal-Diffusive Stability of Counterflow Premixed Flames at Low Lewis Numbers

2014 ◽  
Vol 1040 ◽  
pp. 608-613 ◽  
Author(s):  
Sergey Mokrin ◽  
R.V. Fursenko ◽  
S.S. Minaev
Keyword(s):  
Growth Rate ◽  
Flame Front ◽  
Dispersion Equation ◽  
Premixed Flames ◽  
Stability Diagram ◽  
Material Synthesis ◽  
Lean Burn ◽  
The Stability ◽  
Low Nox Emission ◽  
First Time

Dynamics of radiative, near-limit, stretched premixed flames is investigated analytically and numerically. Investigation of counterflow premixed flames stability is important for the development of new combustion technologies such as those associated with low-NOx emission, lean burn and material synthesis. Emphasis is paid on the linear stability of multiple flame regimes. The present analysis, for the first time, gives out a dispersion equation describing growth rate of small spatial perturbations of the flame front. The stability diagram is obtained and the region of instability is distinguished.

Effect of the mixing fields on the stability and structure of turbulent partially premixed flames in a concentric flow conical nozzle burner

2017 ◽  
Vol 175 ◽  
pp. 180-200 ◽  
Author(s):  
Mohy S. Mansour ◽  
Ayman M. Elbaz ◽  
William L. Roberts ◽  
Mohamed S. Senosy ◽  
Mohamed F. Zayed ◽  
...  
Keyword(s):  
Premixed Flames ◽  
Conical Nozzle ◽  
Partially Premixed Flames ◽  
Partially Premixed ◽  
The Stability ◽  
Concentric Flow
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