On the influence of nozzle geometry on jet diffusion flames under cross-wind

Fuel ◽  
2020 ◽  
Vol 263 ◽  
pp. 116549 ◽  
Author(s):  
Changchun Liu ◽  
Linyuan Huang ◽  
Tiandiao Deng ◽  
Shasha Zhou ◽  
Xinlei Liu ◽  
...  
Keyword(s):  
Diffusion Flames ◽  
Nozzle Geometry ◽  
Jet Diffusion Flames

The Effects of Burner Geometry and Fuel Composition on the Stability of a Jet Diffusion Flame

1997 ◽  
Vol 119 (4) ◽  
pp. 265-270 ◽  
Author(s):  
N. Papanikolaou ◽  
I. Wierzba
Keyword(s):  
Diffusion Flames ◽  
Flame Stabilization ◽  
Nozzle Geometry ◽  
Stream Velocity ◽  
Fuel Composition ◽  
Jet Diffusion Flames ◽  
Aspect Ratios ◽  
Air Stream ◽  
The Stability ◽  
Flowing Stream

The effect of the burner configuration and fuel composition on the stability limits of jet diffusion flames issuing into a co-flowing air stream is presented. Circular and elliptic nozzles of various lip thicknesses and aspect ratios were employed with methane as the primary fuel and hydrogen, carbon dioxide, and nitrogen as additives. It was found that the effects of nozzle geometry, fuel composition, and co-flowing stream velocity on the blowout limits were highly dependent on the type of flame stabilization mechanism, i.e., whether lifted or rim-attached, just prior to blowout. The blowout behavior of lifted flames did not appear to be significantly affected by a change in the nozzle shape as long as the discharge area remained constant, but it was greatly affected by the fuel composition. In contrast, attached flame stability was influenced by both the fuel composition and the nozzle geometry which had the potential to extend the maximum co-flowing stream velocity without causing the flame to blow out. The parameters affecting the limiting stream velocity were studied.

Lift-Off, Reattachment and Blowout Limits of Co-Flow Jet Diffusion Flames

2002 ◽  
Author(s):  
M. Karbasi ◽  
I. Wierzba
Keyword(s):  
Diffusion Flames ◽  
Flame Stabilization ◽  
Nozzle Geometry ◽  
Stream Velocity ◽  
Jet Diffusion Flames ◽  
Air Stream ◽  
Lifted Flames ◽  
Lift Off ◽  
The Stability ◽  
Flowing Stream

The stability behaviour of jet diffusion flames in a co-flowing stream of air was examined. Their lift-off, reattachment and blowout limits were established for methane, propane, ethylene and hydrogen. The co-flowing air stream velocity affected significantly the mechanism of flame stabilization. Different flow regimes where the blowout of lifted flames or attached flames can occur were recognized. A transition region in which both the blowout of lifted flames as well as that of attached flames was observed and identified with respect to the value of the air stream velocity. It was found that the blowout limits for lifted flames in this region were much smaller than for the attached flames. The effects of changes in the nozzle geometry and co-flowing stream composition were also considered.

scholarly journals The Effect of Co-Flowing Stream Velocities on the Flow Characteristics of Jets Issuing From Elliptic Nozzles

1997 ◽  
Author(s):  
N. Papanikolaou ◽  
I. Wierzba
Keyword(s):  
Diffusion Flames ◽  
Flow Characteristics ◽  
Nozzle Geometry ◽  
Laser Doppler Velocimeter ◽  
Circular Nozzle ◽  
Jet Diffusion Flames ◽  
Aspect Ratios ◽  
Air Stream ◽  
Lifted Flames ◽  
Flowing Stream

The flow structure of cold and ignited jets issuing into a co-flowing air stream was experimentally studied using a laser Doppler velocimeter. Methane was employed as the jet fluid discharging from circular and elliptic nozzles with aspect ratios varying from 1.29 to 1.60. The diameter of the circular nozzle was 4.6 mm and the elliptic nozzles had approximately the same exit area as that of the circular nozzle. These non-circular nozzles were employed in order to increase the stability of attached jet diffusion flames. The time-averaged velocity and r.m.s. value of the velocity fluctuation in the streamwise and transverse directions were measured over the range of co-flowing stream velocities corresponding to different modes of flame blowout that are identified as either lifted or attached flames. On the basis of these measurements, attempts were made to explain the existence of an apparent optimum aspect ratio for the blowout of attached flames observed at higher values of co-flowing stream velocities. The insensitivity of the blowout limits of lifted flames to nozzle geometry observed in our previous work at low co-flowing stream velocities was also explained.

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

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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