The effect of swirl and nozzle geometry on the structure of flames and NO(x) emission

Gupta, Ashwani K.; Ramavajjala, M. S.; Taha, Marwa

doi:10.2514/6.1992-766

Cited by 7 publications

(6 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…18 There are several features about the ows of interest that lead to simpli cations in the in uence coef cient analysis compared to the full set of equations[Eqs. (3)(4)(5)(6)(7)(8)(9)(10)(11)]. First, as is the case in gas turbine combustors,the Mach numbers are low enough that changes in pressure have no signi cant effect on density, and the state equation is,…”

Section: In Uence Coef Cientsmentioning

confidence: 99%

“…(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)] in uence coefcients for two streams with area change, heat release, and mixing have been derived following the method developed by Shapiro and Hawthorne 17 and popularized by Shapiro. 18 There are several features about the ows of interest that lead to simpli cations in the in uence coef cient analysis compared to the full set of equations[Eqs.…”

Section: In Uence Coef Cientsmentioning

confidence: 99%

“…IV. Equations (3)(4)(5)(6)(7)(8)(9)(10)(11) are solved by specifying inlet conditions, duct geometry, heat release pro les, and mixing rate and then integrating along the duct in the axial direction. The equations are, thus, parabolic and downstream in uences are not felt.…”

Section: B Conservation Equationsmentioning

confidence: 99%

See 2 more Smart Citations

Confined Swirling Flows with Heat Release and Mixing

Underwood

Waitz

Greitzer

2000

Journal of Propulsion and Power

View full text Add to dashboard Cite

A simpli ed model is used to illustrate global features and ow regimes encountered in swirling ows with combustion, as an approach to providing an overall interpretation of the behavior of primary zone ows in leanpremixed-prevaporized gas turbine combustors. As one example of this, the physical mechanisms that characterize the interactions between swirl and heat addition are described, including the differing effects on recirculation zone formation for low and high values of swirl. The model, which is based on a quasi-one-dimensional control volume formulation, contains many approximations for the relevant ow processes. Nevertheless, comparisons of this simpli ed model with results from an axisymmetric Navier-Stokes code support the utility of the approach for gaining physical insight into the overall behavior of these parametrically complex ows. Nomenclature A= control volume area b 0 = planar shear layer growth rate C p = speci c heat of air at constant pressure E = Eckert number, (u 1 ¡ u 2 ) 2 / C p t T 1 h = enthalpy L = duct length M = Mach number = momentum, Çmu Çm = mass ow Pr t = turbulent Prandtl number p = static pressure R = radius of duct Re b = Reynolds number based on shear layer thickness, D U b/ m t r = velocity ratio, u 1 / u 2 s = density ratio, q 1 / q 2 T = static temperaturē U = average axial velocity of core and outer streams u = velocity in axial direction v = velocity in circumferential direction w = velocity in radial direction z = coordinate in axial direction a = area ratio, A D / A 1 C = circulation D U = velocity difference, u 1 ¡ u 2 d = radius of vortex core g = ratio of speci c heats at constant pressure, C p1 / C p2 m t = effective turbulent viscosity N = mixing coef cient q = density s = temperature ratio, T 1 / T 2 u = equivalence ratio X = swirl ratio, C / 2p d u 1 Subscripts c = centerline D = duct m = mixing pr = product formation due to chemical reaction

show abstract

Section: In Uence Coef Cientsmentioning

confidence: 99%

Section: In Uence Coef Cientsmentioning

confidence: 99%

See 1 more Smart Citation

Confined Swirling Flows with Heat Release and Mixing

Underwood

Waitz

Greitzer

2000

Journal of Propulsion and Power

View full text Add to dashboard Cite

show abstract

“…The effect of mixing and flame attachment on pollutant formation, specifically NO x emissions has been widely reported (3)(4)(5)(6)(7). Researchers have shown that the resultant NO x emissions are highly dependent on flame attachment or the extent of pre-mixedness for detached flames, both of which are dependent on burner geometry (4)(5)(6)(7)(8).…”

Section: Introductionmentioning

confidence: 99%

“…Researchers have shown that the resultant NO x emissions are highly dependent on flame attachment or the extent of pre-mixedness for detached flames, both of which are dependent on burner geometry (4)(5)(6)(7)(8). The resulting pollutant emissions greatly depend on flame position.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Coal Particle Flow Patterns in Low Nox Burners

Yurteri¹,

Ogden

Sinclair

et al. 2001

View full text Add to dashboard Cite

It is well understood that the stability of axial diffusion flames is dependent on the mixing behavior of the fuel and combustion air streams. Combustion aerodynamic texts typically describe flame stability and transitions from laminar diffusion flames to fully developed turbulent flames as a function of increasing jet velocity. Turbulent diffusion flame stability is greatly influenced by recirculation eddies that transport hot combustion gases back to the burner nozzle. This recirculation enhances mixing and heats the incoming gas streams. Models describing these recirculation eddies utilize conservation of momentum and mass assumptions. Increasing the mass flow rate of either fuel or combustion air increases both the jet velocity and momentum for a fixed burner configuration. Thus, differentiating between gas velocity and momentum is important when evaluating flame stability under various operating conditions. The research efforts described herein are part of an ongoing project directed at evaluating the effect of flame aerodynamics on NO x emissions from coal fired burners in a systematic manner. This research includes both experimental and modeling efforts being performed at the University of Arizona in collaboration with Purdue University. The objective of this effort is to develop rational design tools for optimizing low NO x burners. Experimental studies include both coldand hot-flow evaluations of the following parameters: primary and secondary inlet air velocity, coal concentration in the primary air, coal particle size distribution and flame holder geometry. Hot-flow experiments will also evaluate the effect of wall temperature on burner performance.Cold-flow experiments were conducted at Purdue University using a 0.45 meter square Plexiglas down-flow flow visualization chamber. The 1 meter tall chamber was equipped with X-Y-Z traversing laser doppler velocimetry/phase doppler particle analyzer (LDV/PDPA). The overall purpose of the cold-flow research is to investigate the gas-solid interactions and particle motion in an isothermal coaxial jet as a function of various inlet parameters including velocity ratio and of particle properties: particle size and the particle size distribution. By utilizing a bimodal mixture of large and small particles, we can more closely approximate the flow characteristics of pulverized coal streams, and enables us to study the possible changes in the particle behavior of different sizes in the presence one another. Lagrangian particle tracking was employed to help verify the proposed mechanism for particle motion and gas-solid interaction for different velocity ratios.A computational study using the Fluent 4.5 CFD package was performed to evaluate the predictive capability of the standard k-ε turbulent model for the coaxial jet flow behavior and to calculate particle trajectories and compare these to the cold-flow results. The standard k-ε model relates the Reynolds stress using the Boussinesq eddy viscosity assumption. While, the Boussinesq eddy-viscosity model de...

show abstract

Combustion enhancement using induced swirl

Guillaume

LaRue

1995

Experiments in Fluids

View full text Add to dashboard Cite

The effect of swirl and nozzle geometry on the structure of flames and NO(x) emission

Cited by 7 publications

References 2 publications

Confined Swirling Flows with Heat Release and Mixing

Confined Swirling Flows with Heat Release and Mixing

Optimization of Coal Particle Flow Patterns in Low Nox Burners

Combustion enhancement using induced swirl

Contact Info

Product

Resources

About