A numerical study on flame stability at the transition point of jet diffusion flames

1996 ◽  
Vol 26 (1) ◽  
pp. 27-34 ◽  
Author(s):  
H. Yamashita ◽  
M. Shimada ◽  
T. Takeno
Keyword(s):  
Transition Point ◽  
Diffusion Flames ◽  
Numerical Study ◽  
Flame Stability ◽  
Jet Diffusion Flames

Numerical Study on Merging and Interaction of Jet Diffusion Flames

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
T. C. Ho ◽  
S. C. Fu ◽  
Christopher Y. H. Chao ◽  
Sharad Gupta
Keyword(s):  
High Velocity ◽  
Diffusion Flames ◽  
Numerical Study ◽  
Separation Distance ◽  
Flame Height ◽  
Jet Flame ◽  
Jet Diffusion Flames ◽  
Pressure Relief Valves ◽  
Computational Fluid Dynamics Cfd ◽  
The Individual

A high velocity jet fire can cause catastrophic failure due to flame impingement or radiation. The scenario becomes more complicated when multiple jet fires exist following ignition of release from pressure relief valves (PRV) as the thermal effect not only distorts the individual jet flame but also changes the flame height and temperature profile and such kind of high velocity jet flames have not been studied in the past. Therefore, prediction of the flame shape including the merging and interaction of multiple jet fires is essential in risk analysis. In this paper, fire interaction of two high velocity (>10 m/s) jet fires is investigated using computational fluid dynamics (CFD) techniques. Different radiation models are analyzed and validated by experimental data from the literature. Based on the simulation result, the merging of high velocity jet fires is divided into three stages. An empirical equation considering the fire interaction for the average flame height with different release velocities and separation distance is developed. The flame height increases dramatically when the separation distance decreases resulting in a shortage of oxygen. So, part of the methane is reacted in a higher height, which explains the change in the merging flame height and temperature.

Effects of partial gravity and g-jitter radiation from jet diffusion flames

1997 ◽  
Author(s):  
M. Bahadori ◽  
L. Zhou ◽  
D. Stocker ◽  
M. Bahadori ◽  
L. Zhou ◽  
...  
Keyword(s):  
Diffusion Flames ◽  
Jet Diffusion Flames ◽  
Partial Gravity ◽  
Jitter Radiation

A PIV investigation of weakly buoyant laminar jet diffusion flames

2000 ◽  
Author(s):  
Mark Wernet ◽  
Paul Greenberg ◽  
Peter Sunderland ◽  
William Yanis
Keyword(s):  
Diffusion Flames ◽  
Laminar Jet ◽  
Jet Diffusion Flames

The blowout mechanism of turbulent jet diffusion flames

2006 ◽  
Vol 145 (3) ◽  
pp. 481-494 ◽  
Author(s):  
Chih-Yung Wu ◽  
Yei-Chin Chao ◽  
Tsarng-Sheng Cheng ◽  
Yueh-Heng Li ◽  
Kuo-Yuan Lee ◽  
...  
Keyword(s):  
Diffusion Flames ◽  
Turbulent Jet ◽  
Jet Diffusion Flames

A Numerical Study on the Reactivity of Biogas/Reformed-Gas/Air and Methane/Reformed-Gas/Air Mixtures at Gas Turbine Relevant Conditions

2016 ◽  
Author(s):  
Pablo Diaz Gomez Maqueo ◽  
Philippe Versailles ◽  
Gilles Bourque ◽  
Jeffrey M. Bergthorson
Keyword(s):  
Gas Turbine ◽  
Laminar Flame ◽  
Numerical Study ◽  
Flame Temperature ◽  
Flame Speed ◽  
Flame Stability ◽  
Laminar Flame Speed ◽  
Fuel Reforming ◽  
Numerical Work ◽  
Chemical Effects

This study investigates the increase in methane and biogas flame reactivity enabled by the addition of syngas produced through fuel reforming. To isolate thermodynamic and chemical effects on the reactivity of the mixture, the burner simulations are performed with a constant adiabatic flame temperature of 1800 K. Compositions and temperatures are calculated with the chemical equilibrium solver of CANTERA® and the reactivity of the mixture is quantified using the adiabatic, freely-propagating premixed flame, and perfectly-stirred reactors of the CHEMKIN-Pro® software package. The results show that the produced syngas has a content of up to 30 % H2 with a temperature up to 950 K. When added to the fuel, it increases the laminar flame speed while maintaining a burning temperature of 1800 K. Even when cooled to 300 K, the laminar flame speed increases up to 30 % from the baseline of pure biogas. Hence, a system can be developed that controls and improves biogas flame stability under low reactivity conditions by varying the fraction of added syngas to the mixture. This motivates future experimental work on reforming technologies coupled with gas turbine exhausts to validate this numerical work.

Effects of finite-rate chemistry and detailed transport on the instability of jet diffusion flames

2014 ◽  
Vol 745 ◽  
pp. 647-681 ◽  
Author(s):  
Yee Chee See ◽  
Matthias Ihme
Keyword(s):  
Transport Properties ◽  
Diffusion Flames ◽  
Diffusive Transport ◽  
Mean Flow ◽  
Stability Behaviour ◽  
Jet Diffusion Flames ◽  
One Step ◽  
The Mean ◽  
Modelling Assumptions ◽  
The Stability

AbstractLocal linear stability analysis has been shown to provide valuable information about the response of jet diffusion flames to flow-field perturbations. However, this analysis commonly relies on several modelling assumptions about the mean flow prescription, the thermo-viscous-diffusive transport properties, and the complexity and representation of the chemical reaction mechanisms. In this work, the effects of these modelling assumptions on the stability behaviour of a jet diffusion flame are systematically investigated. A flamelet formulation is combined with linear stability theory to fully account for the effects of complex transport properties and the detailed reaction chemistry on the perturbation dynamics. The model is applied to a methane–air jet diffusion flame that was experimentally investigated by Füriet al.(Proc. Combust. Inst., vol. 29, 2002, pp. 1653–1661). Detailed simulations are performed to obtain mean flow quantities, about which the stability analysis is performed. Simulation results show that the growth rate of the inviscid instability mode is insensitive to the representation of the transport properties at low frequencies, and exhibits a stronger dependence on the mean flow representation. The effects of the complexity of the reaction chemistry on the stability behaviour are investigated in the context of an adiabatic jet flame configuration. Comparisons with a detailed chemical-kinetics model show that the use of a one-step chemistry representation in combination with a simplified viscous-diffusive transport model can affect the mean flow representation and heat release location, thereby modifying the instability behaviour. This is attributed to the shift in the flame structure predicted by the one-step chemistry model, and is further exacerbated by the representation of the transport properties. A pinch-point analysis is performed to investigate the stability behaviour; it is shown that the shear-layer instability is convectively unstable, while the outer buoyancy-driven instability mode transitions from absolutely to convectively unstable in the nozzle near field, and this transition point is dependent on the Froude number.

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