Index

Simulation of the BERL 300 kW Natural Gas Flame using FLUENT/UNS

Rajesh Nair Fluent Inc.,

10 Cavendish Ct. Lebanon, NH 03766

Abstract

Results for the swirling , un-staged , 300 kW BERL natural gas flame have been obtained using the CFD code FLUENT fUNS. The solver is based on a fully unstructured finite volume scheme. The predictions have been compared to those obtained using the structured solver FLUENT. Some comparisions with measurements are also made. 'IUrbulence is modeled by means of the standard k - f model. Two different models to describe the turbulence chemistry interaction have been considered : i) a conserved scalar pdf model, ii) the Magnussen-Hjertager eddy breakup model. For the first sub-model, the f3 probability density function is used, while the second uses eit her a single step reaction scheme or a two-step reaction scheme. Radiation is computed using the P-l differential approximation and the WSGGM (Weighted Sum of Gray Gases Model) is used to calculate the radiative properties . Comparison of velocities , temperature and species concentrations for both FLUENT and FLUENT/UNS using the conserved scalar pdf model have been made at three stations downstream of the quarl. Predictions of velocities , t emperature and species using the different schemes (pdf, Magnussen single step, and Magnussen two-step) are also compared to experimental data at some stations.

Introduction

Numerical modeling of natural gas combustion is a complex phenomenon influenced by a large number of interacting processes. Comprehensive testing and validation is necessary to establish the range of applicability and level of confidence in commercial CFD codes that can eventually be used for design of industrial burners. This task is often made difficult by the lack of data from suitable benchmark industrial problems. The present work resulted from validation studies carried out at Fluent Inc. for the experiments conducted at the Burner Engineering Research Laborat.ory (BERL) as part of the "Scaling 400" study, whereby experimental measurements were taken for combust.ors ranging in size from 300 kW to 12 MW. This particular study deals with an unstaged 300 kW, nat.ural gas flame. Data from the experiments were collected by Sayre et al. and are published in [1].The quality of t.he present. benchmark[l] is deemed to be excellent insofar as the geometry and flow boundary conditions are well defined . Besides, the extensive measurements are well suited for code validation .

Objectives

FLUENT/UNS is a general purpose CFD code that was released in June 1996. It offers several advantages over conyent.ional codes t.hat are based on a structured framework, for instance, decreasing time used in setting up the geometry and grid, allowing adaption to evolving solutions to capture high gradients, true dynamic allocation of memory and parallel processing. This paper is part of a two-step internal project: (i) Compare FLUENT/UNS predictions wit.h experimental data and previously obtained predictions for the 2-d axisymmetric case using FL U­ENT (ii) Compare predictions obtained from full 3-d simulations against experimental data. This paper reports t.he progress made toward the first part of the project.

The principal purpose of this study was to validate predictions obtained by using a new unstructured solver , FLUENT/UNS, against predictions made by a structured solver, FLUENT. This was to ensure that the new solver could be used for similar applications with the same reliability that characterized the structured solver. Further , some comparisons were also made with appropriate in-flame measurements at various stations in the furnace. The objective is not to describe any new model of turbulence-chemistry interaction or combustion , but to validate existing models available in the literature and implemented in FLUENT/UNS.

Problem Description

The flame considered is unstaged natural gas fired in a 300 k W swirl-stabilized burner (Figure 1). The furnace is vertically fired and of octagonal cross-section, with a conical furnace hood and cylindrical exhaust duct. The furnace wall may either be lined with refractory material or water-cooled. The burner features 24 radial fuel

1

injection holes and a bluff centerbody. Air is introduced through an annular inlet and moveable swirl blocks are used to impart swirl. A detailed description of the geometry is available in [1].

Two configurations were considered during experiments, one with water cooled furnace walls, and the other with the furnace wall lined with refractory. The current study presents results only for the case with the refractory lining , i.e., the so-called "hot-wall" configuration. The problem was modeled as axi-symmetric, and appropriate area adjustments were made to account for the 2D representation of an inherently 3D problem . A close-up view of the furnace quarl area is shown in Figure 2. Care was taken to ensure that the cross-sectional areas of the modeled furnace and real furnace remained the same. It is worthwhile studying the axisymmetric model before embarking on the more complicated and time consuming 3D modeling effort. The wall thermal conditions for the hot-wall configuration are given in Table 1. [1]

Boundary Temperature (K) Emissivity Walls near the inlet ducts 312 0.6 Bluff body front wall 1173 0.6 Inlet duct insert (oblique) 1173 0.6 Quarl wall (oblique) 1273 0.6 Furnace bottom wall 1100 0.5 Furnace cylinder wall (hot) profile 0.5 Furnace top wall (hood) 1305 0.5 Chimney wall 1370 0.5

Table 1: Wall Thermal Conditions

The profile along the furnace cylinder wall was given by the following equation[l]:

T(x) = ao + al(x + 0.195) + ... + a6(x + 0.195)6 (1)

where 0 ~ x ~ 1.65 m is the position along the wall and the coefficients ai are given in Table 2.

ao 1.257 x 10J

al -2.1777 x10J

a2 9.93349 x 10J

a3 -1.74799 x104

a4 1.46151 x 104

a5 -5.83885 x 103

a6 8.98612 X 102

Table 2: Coefficient.s of the Temperature Profile along the Furnace Cylinder Wall in the "Hot-Wall" Configuration

Formulation

The st.eady-state. Reynolds averaged N avier-Stokes equations for mass, momentum, energy and scalar transport are used to describe the flow physics. The density is obtained using the ideal gas law. The standard k - f turbulence closure model was considered appropriate because of the relatively low inlet swirl (swirl number=0.56). Also, for combusting flows. the swirling inlet flow is accelerated due to combustion and the importance of the centrifugal forces due to swirl decreases vis a vis the inertial forces [2]. The two different models used for turbulent combustion are now described briefly.

2

The Eddy Breakup model

The Magnussen eddy breakup model is an intuitively simple model , where the reaction rate is computed as the minimum of the kinetic reaction rate and the mixing rate. Also, for global reaction modeling , it is computationally tractable. The natural gas composition is as shown in Table 3. Associated species included CO2, N2, O2, and H20. Mass balance equations are solved for each species. To account for the effects of dissociation of combustion products, the average specific heats of CO2, H20, and O2 were modified according to Table 4. Specific heats for other species were taken from J ANN AF tables.

Inlet Flows Air Fuel Mixture Mass Fraction of "fuel" 0 0.97 Mass Fraction of CO2 0 0.008 Mass Fraction of N2 0.7685 0.022 Mass Fraction of O2 0.2315 0

Table 3: Mass Fractions in the Inlet Flows for the Eddy Breakup Model

Species CO2 H2O O2 ao 5.35446e+02 1.9378e+03 8.7632e+02 al 6.39334e-01 -5.90386e-01 6.1414e-02 a2 -1.8225ge-04 1.2145e-03 1.8610e-04 a3 -5.9556e-08 -7.1582e-07 -3.0062e-07 a4 3.78408e-11 1.5191e-10 2.2948e-10 as -8.5396e-14 a6 1.2237e-17

Table 4: Coefficients of the Polynomial Function Defining the Specific Heat Capacities of the Species

The source and the sink terms in the chemical species transport equations are computed according to the Magnussen model. Here, the rates and formation and destruction of the chemical species considered are related to eddy dissipation rate. The reaction rate is computed to be the minimum of the kinetic and the mixing rates as described by Magnussen and Hjertager[3]. No modifications were made to the values of the mixing rate coefficients A and B originally suggested, i.e., A = 4 and B = 0.5. The combustion reaction for the single step scheme was described according to:

fuel + 2.03302 ---4 1.022C02 + 2.022H20

For the two-step scheme, the reaction was described by:

fuel + 1.52202 ---4 1.022CO + 2.022H20

The conserved scalar pdf model

(2)

(3)

(4)

The pdf model is extremely useful when time scales of reaction are much smaller than the mixing time scale. Under these conditions, the entire reaction mechanism can be described by a system of species going to equilibrium. Such

3

a scheme takes into account dissociation into multiple species and the effects of such dissociation on specific heat capacities of the mixture, a phenomenon that is difficult to simulate when using the Magnussen model. Also , unlike the Magnussen model , it does not require adjusting of model constants . The disadvantages primarily rest in the fact that when finite rate chemistry effects are very important (i.e., when the reaction and mixing time scales are of the same order), the scheme does not predict the correct behavior.

In the pdf model, the instantaneous thermochemical state of the fluid is related to a single conserved scalar quantity, namely, the mixture fraction f, defined by

(5)

where Zk is the element mass fraction for some element, k. Subscript 0 refers to the value at the oxidizer stream inlets and subscript F refers to the value at the fuel stream inlets. Then, for any <Pi, where <Pi can represent instantaneously, temperature or concentration of any desired species,

and

<Pi = [P(f)<Pi(f)d/

where p(f) represents the probability density function for the scalar f.

(6)

(7)

For this relationship to hold, the requirements necessary are: (i) the flame must be of the diffusion type, with separate fuel and oxidizer inlets (ii) the system should be adiabatic and incompressible and (iii) the Lewis number must be unity. vVhen the flame is non-adiabatic, the influences of heat loss on turbulent enthalpy fluctuations are ignored, and averaging is done by assuming that <Pi = <Pi(!, Ii), where Ii is the time mean enthalpy. A {3 pdf shape is assumed for the probability distribution function, and equilibrium chemistry is used with a partial equilibrium mL'\."t.ure fraction limit of 0.064, the assumption being that equilibrium exists upto this near-stoichiometric value of the mixture fraction. Chemical equilibrium is computed by means of an algorithm for Gibbs' free energy minimization. Thirteen (13) species and radicals were assumed to exist in the equilibrium mixture, namely, CH4 ,

C2 H6 1 C3 Hg , C4 H lO , CO2 , N2 , O2 , CO, H20, H2 , OH, Hand O. The so-called "look-up" table is computed once, and this allows the solver to interpolate for the desired species concentrations from the table as a function of the mixture fraction, mixture fraction variance, and enthalpy. The adiabatic flame temperature at atmospheric pressure and inlet fuel and air temperatures of 312 K was predicted to be 2200 K at stoichiometry.

Numerical Procedure

FLUENT/UNS uses a general collocated finite volume scheme, where the cells can be arbitrary unstructured convex polyhedra. Quadrilateral, hexahedral, triangular, tetrahedral or prismatic cells may be used. The transport variables are stored at cell centers, thereby ensuring conservation for arbitrary control volumes. The discretization scheme used is second order accurate, the pressure-velocity coupling is handled using the SIMPLE algorithm and the solution procedure uses a variant of the multigrid procedure detailed in Hutchinson and Raithby[4]. Specifications set out in the benchmark experiments for the inlet air velocity profiles and wall temperatures were followed when setting boundary conditions.

The computational grid is a non-orthogonal quadrilateral grid containing 100 by 183 nodes in the radial and axial directions respectively (9784 quadrilateral cells). Appropriate clustering of nodes is observed in the quarl region as well as near the centerline (Figure 3). For the structured solution, a total of 18300 cells were used, thus FL -ENT/UNS allowed the same solution with half the memory usage. A unique feature available in FLUENT/UNS is the capability of solution adaption, whereby one may adapt/refine the grid to gradients of any desired variable. This is extremely useful when resolving high gradients locally, instead of carrying unnecessary baggage in the form of grid points at. places where they may not be necessary as would be the case in a structured solver. (Figure 4)

4

Results and Discussion

The velocity fields obtained from both the eddy-breakup and the conserved scalar models are displayed along with experimental measurements as radial profiles at three different stations, 27 mm downstream of quarl, 109 mm downstream of quarl and 343 mm downstream of quarl (Figures 5-7). The formation of the internal and external recirculation zones can be clearly seen. Predictions obtained from the structured (FLUENT) and the unstructured (FLUENTfUNS) solvers are seen to be in excellent agreement. The unstructured solver is seen to perform just as well as t.he structured solver for predicting flow velocities indicating that it may be used the with the same degree of confidence as the structured solver. Comparing the different modeling schemes used in the unstructured solver (FL UENT fUNS) to the experimental data, both the eddy breakup and the pdf models are seen to overpredict the strengt.h of the reverse flow velocities near the centerline. It is believed that this is because of the 2d axisymmetric represent.ation of the 24 injection holes by an axisymmetric slit. The 2d assumption causes delayed mixing between the fuel and air, hence, the heat release in the near burner zone is smaller. Thereby the effective swirl number is not reduced [2] to the same degree as it would be in the 3D case, where the heat release would be higher. The peak velocities are also overpredicted. Further, the peak velocities do not decay as fast as indicated by the experimental dat.a.

Tangential velocity profiles are shown in the next set of figures (Figures 8-10). The comparisons reveal that at 27 mm downst.ream of quarl, both the structured and the unstructured solvers capture the double peak structure revealed in the experiments , although the magnitude of the inner peak is underpredicted. Comparing different modeling schemes , t.he pdf model predicts the swirl velocities better than the eddy breakup model (single step chemist.ry). At. the station 109 mm downstream of the quarl, all schemes predict a higher decay of the tangential velocit.y as compared to experiments. This is a well known shortcoming of the k - t model that has been used.

Temperat.ure profiles shown in Figures 11-13 show that predictions obtained from both solvers are very similar. However, the predictions indicate a longer and thinner flame than experimentally observed (Figure 14). Again, this is because of t.he axisymmetric assumption, since the gas is assumed to issue from an annular slit rather than 24 discret.e holes. Peak temperatures are predicted to occur further downstream in the combustor as compared to experiment.al dat.a. The pdf model shows the presence of a sharp spike, which is quite possibly an inherent limit.at.ion of t.he model resulting from ignoring finite chemistry effects that are important in this region. The eddy breakup model, on the other hand, does not show the presence of such a peak. Further downstream, the same behaviour is seen with the temperature being underpredicted by approximately 130 K in all models in the outer regions of the combustor, while near the centerline, the temperature is higher than indicated by experiment.

Radial profiles of O2 and CO2 (dry volume per cent) are shown at the three different stations (Figures 15-17). The unst.ruct.ured solver (FLUENT fUNS) predictions are in good agreement with the predictions obtained from the st.ruct.ured solver, FLUENT. This indicates that the unstructured solver can be used with the same degree of confidence as t.he structured solver. Figures 18 and 19 show comparisons of O2 and CO2 (dry mole fraction) concent.rat.ions t.o experimental data at the station 27 mm downstream of the quarl.

Profiles of O2 in t.he near burner region (rich flame) show predictions of mole fraction close to zero, a consequence of t.he equilibrium chemistry assumption inherent in the pdf model. Finite rate chemistry effects, that are important in t.he rich flame region are thought to be responsible for the errors in prediction of species concentrations. Errors in t.he predict.ion of t.urbulent mixing in the Magnussen model owing to variance in the mixing constant A for different flames can be responsible for some of the differences observed. Errors also occur in the PDF model because of the modeling of t.he t.ransport equation for the mixture fraction and its variance. Flow field modeling errors can arise due t.o t.reat.ment. of the 3-dimensional furnace geometry as a 2-dimensional, axisymmetric configuration.

Conclusions and Future Efforts

Validat.ions for a swirling natural gas flame have been carried out for the unstructured solver FLUENT fUNS against a st.ruct.ured solver (FLUENT). Comparisons to experimental data have also been shown. Two combustion models were used the eddy breakup model with both the single step and two-step reaction schemes, and the partial

5

equilibrium, conserved scalar pdf model. This work formed the first part of a two step internal project to validate the new unstructured solver against experimental data. Predictions obtained from the unstructured solver are seen to match those from the structured solver very well. Predictions are also seen to be in relatively good agreement with experimental results. Some of the differences seen in comparisons to experimental results are due to modeling the 3-D problem as axisymmetric. This study provided the first step to comprehensive validation of a new tool. The single step chemistry model was observed to be not as accurate or comprehensive with respect to information as the two-step and the pdf models. Therefore, only the two-step chemistry and the pdf models will be analyzed in the second part of the project. The next step will be to simulate the full 3-D problem along with a comparison of the performance of the different combustion models that are available. A full comparison of predicted species concentrations with experimental data will also be carried out.

Acknowledgements

The author would like to acknowledge the prior work done by Dr. Meriem Makhlouf of Fluent Europe that helped in setting up the current validation problem with ease. The author would also like to thank Andre Peters of Fluent Inc. for helpful discussions.

References

1. Sayre, A., Lallemant, N., Dugue, J., and Weber, R., "Scaling Characteristics of Aerodynamics and Low-NOr properties of Industrial Natural Gas Burners, The SCALING 400 Study, Part, IV: The 300 kW BERL Test Results," IFRF Doc No F40/y/11, International Flame Research Foundation, The Netherlands.

2. Weber, R., Peters, A. A. F., Breithaupt, P. P., and Visser, B. M., Mathematical Modeling of Swirling Pulverized Coal Flames: What can Combustion Engineers expect from Modeling. ASME FACT 17, 71. Book No. H00827-1993.

3. Magnussen, B. F. and Hjertager, B. H., On Mathematical Modeling of Turbulent Combustion with Emphasis on Soot Formation and Combustion, Seventeenth Symposium (International) on combustion, The Combustion Institute, (1976).

4. Hutchinson, B.R., and Raithby, G.D., A Multigrid Method based on the Additive Correction STrategy, Num. Heat Transfer, v. 9, pp. 511-537, (1986).

5. Peters, A.A.F, and Weber. R., Mathematical Modeling of a 2.25 MW Swirling Natural Gas Flame. Part 1: Eddy Breakup Concept for Turbulent Combustion; Probability Density Function Approach for Nitric Oxide Formation, Combustion Science and Technology, vols. 110-111, pp. 67-101. (1995)

6. Wild, P.N., and Faltsi-Saravelou, 0., Mathematical Modeling of a 2.25 MW Swirling Natural Gas Flame. Part 2: Conserved Scalar Approach for Turbulent Combustion, Combustion Science and Technology, vols. 110-111, pp. 103-121. (1995)

7. Kaufman, K.C., and Fiveland, W.A., Pilot Scale Data Collection and Burner Model Numerical Code Validation, topical report for GRI contract 5093-260-2729.

6

761 mm

382mm

1651 mm

insulating board

I 106~.8 mm

water-cooled jacket

optional refractory brick

location of the measurements

Figure 1: Problem geometry and description

7

----_ 195mm

........ .. ........ .J--------.

swirling : -: . :- :- :- :- :- :- :- 1.66 Do combustion air .................. =====rf

natural gas =--------24 hoiSs - Ifo.S6 Dei [)~ 1 ~1: ~~ o 1.8 mm r-------, 100 = 87 mml

1.33 Do

Figure 2: Closeup of burner quarl

Figure 3: Closeup of grid in the vicinity of the quarl

8

~ .1 .1

l"-

I--

~C ~ r-l---~ b:=:~ ~.----Vl,.-- ~t:::: '--~VVVl,.--~ f:::::~ r-r-vV vV l--l..-----~r::: ~~ ~ vV vJ---VVJ..-.--""~V [::::::v- I--r-"'- V V V V ~ vI---~~ ~

_v~1--__ I--vv v-~ ~t::: :::::::::= >--~I--- vf..--' __ VV/ i---"'-_- f..---:::: -

1---'-- V V I--'-i---":"- - - f.-- _ t:::=-- ---- .--v V f.--VV I--i---":..-:"- - - --r::: f..--- _ ---v VV V f.-- r--'-r:: t:::t::t:: ~::::::::::;::v ~:::: ~:::: ---v v'-- f.-- --I--'-~ I--t:::..-::: -::::: --t::::: f..--- _ ~--~,.,.- V --I--'-~I--:..-:"- - --v 1----' ____ >--,-- -- v'-- ...... ---1---1--1--:..-:..-::::::----v- v--,.....-'----i---"V 1---- ,.-1- I-I-~I--::::i.-I--:"-:"-I---~I--v~

,....,....,.... ~v VV I---- I-~ I- r::: f-I-- __ i.-t:::I--~ 1--::::: I-- i:==L-- ~ >--~ ... -'_'-c--'--'---1--1--"""- f 1:=.-~ 1== ---:::::: ;::::::""':::1---1::> c-e-----~ v--~I- ~ 1--1-- I-f- f- "'-1--1- .-1--1--:..-:"-:..-~ 1-1-1-'-I--:"-V -~~ - ~ t: I-~.-~ t:::t::t:: ~ ----- l----~ ~ ~~ I-~ ~ ~~ - ~:: ~~ ::::1--1-- ~ ----- l----~

~ ........ ~ 1:=1== 1==e:1==t::e:t:: ........... l---f---- I----I-I-f-I- f- '-' I- :--~ L---~ I----~ ~t:SL-~~I--~t:=~1---~ f.----

~ I--~ ~ 1---1--- ~ I--I----- f.----~e-- _- ........... 1-- ~ ~

II f..-I--I-- :--1-- l--~ I---~ I--~I--~ :--I--~ ~~~ I---~ H I--~~ 1---1--- ~

~

H -1-1--1--I--I--~~ I---~I---~ ~I---

1-1-1-- I--~I-- ~I---~ I---...--- f-I-- f--I--- 1----1---

f.----I--f--~I--I--1--1---~~ f...--I---!----_ -f- f--I-- '--" ~ --:.---- f..---f---~

_I-f--I--~ I---_f--f--- f..---f----- r--_f--f--I-- ___ ~

_>--I--~- ---<__ -I--

f--r----- i..--

Figure 4: View of grid adapted to mixture fraction gradients

9

I UNS :- - FLUENT

6.00e-.Ol 6 .~01

S.OO$+OI S .~OI

4.00$+01 4 .~01

3.00..01 3.~01

2.~01 2 .~01

Axial Axial veloCi~ 1.00$+01 velocl~ 1.~01

(mts (mts O.OOHOO o.~()()

-1.00$+01 · 1 .~01

·2.00$+01 -2 .~01

-3.00$+01 -3.~01

0.1 0.2 0.3 0.4 05 0.6 0.1 0.2 0.3 0.4 05 0.6

Position (m) Position (m)

Figure 5: Axial velocity profiles at 27 mm downstream of quarl

~~NT 35<1e+{I1 4 .~01

3JX~1 350&+01

3.~01

2..sc..{11 250&+01

2.Q\. ..... {I1 2 .~01

Axial 150. ..... {I1 Axial 150&+01

veloCi~ (mts 1.Q\. ..... {I1

veloCi~ (mts 1 .~01

s .~()()

s.(,_ «\ .. o.~()()

(I.OX ..... «\ -s .~()()

..s.ox ..... «\ - 1 .~01

0 0.1 0.2 0.3 0.4 05 0.6 0 0.1 0.2 0.3 0.4 05 0.6

Position (m) Position (m)

Figure 6: Axial velocity profiles at 109 mm downstream of quarl

~~LENT 3., --':>1 3.~01

25< .... '1 250&+01

2.(.: .... '1 2 .~01

150. ........ '1 150&+01

Axial Axial velOCi~ I _OX ...... '1 veloCI~ 1 .~01

(m's (mts

5.,.: ...... , . s .~()()

\1 \: ~ ........ x· o.~()()

-5..,:,:_ " -S .~()()

0.1 0.2 0.3 0.4 05 0.6 0.1 0.2 0.3 0.4 05 0.6

Position (m) Position (m)

Figure 7: Axial velocity profiles at 343 mm downstream of quarl

10

~ •• ~~NT 1.\0..0\

\ .00..0\

8.00..00

8.00..00

7.00..00

6.00..00 Tangential

5.00..00 velocl~ {m's • . 00..00

3.00..00

2 .00..00

1.00..00

0.00..00

1 .• 0..0\

1.20..0\

1.00..01

Tangential 8.00...00 Velocity

(m's) 6.00...00

• . 00...00

2.00...00

1.20..0\

1.00..0\ ,.

' .00..00

Tangential 6.00..00

velocl~ {m's

4.00..00

2.00..00

0.00..00 0.\ 0.2 0.3 0 .• 0.5 0.6 0.1 0.2 0.3

Position (m) Position (m)

Figure 8: Tangential velocity profiles at 27 mm downstream of quarl

........ __ .. _-_ ... . __ ......... .

1.40..01

1.20..01

1.00..01

8.00..00

Tangential Velocity 6.00..00

(m's)

• . 00..00

2.00..00

0 .• 0.5 0.6

0.00...00 +----,--"""T"--.....----r---...--'---, O.OO"OO+----,--"""T"--.....----r---...----,

Tangential Velocity

(m's)

2.00..00

0. \ 0.2 0.3 0.4 0.5 0.6 0.1 0.2 0.3

Position (m) Position (m)

Figure 9: Tangential velocity profiles at 109 mm downstream of quarl

1.20..01

1.00..0\

8.00..00

Tangential 6.00..00

Velocity (m's)

• . 00..00

2.00..00

0 .• 0.5 0.6

O.IX-"'OO+----,_-"""T"--.....----r--"""T"" ...... --, O.OO"OO+----,--"""T""--.....----r--"""T""---, o 0.1 0.2 0.3 0.4 0.5 0.6 0.\ 0.2 0.3 0 .• 0.5 0.6

Position (m) Position (m)

Figure 10: Tangential velocity profiles at 343 mm downstream of quarl

11

I" ' ~~NT 2.20..CO

1.80..CO

Static 1.40..CO

Temperature (k) 1.20..CO

1.00..CO

... ...... __ ...... ---_ ...... .. .. _ ......... . _--- .... . .. .. .

2.20.. co

2.00..CO

1.80..CO

1.so..CO

Static uo..co

Temperature (k) uo..co

1.00..CO

8.00..02

· ...

6.00..02 +---,.....----.----r---,.....----.---.., 6.00..02 +--...;...,,.....----r---r---,.....----.----.

2~CO

1.8e-CO ••

Static Temperature 1.4c-CO

(k)

l~CO

0.1 0.2 0.3 0.4 0.5 0.6 0.1 0.2 0.3

Position (m) Position (m)

Figure 11: Temperature profiles at 27 mm downstream of quarl

2.2o..CO "

2.00..CO

1.80..CO

1.so..CO

Static Temperature 1.40..CO

(k) -- -_ ... __ ...... _----- .... -.............. _- ..... ...

l.2o..CO

1.00..CO

:\

;. .... .." ...

li I' •• ...:--.:.:.;.: .-.~ .... ----

\i.. : : ~ : :/

•. eoc...."C2 +-----.r-----r---r--......,,.....----r-~ 8.00..02

Static Uil'-"+<O

T~ture (k)

1 .... '"-<0

0.1 0.2 0.3 0.4 0.5 0.6 0.1 0.2 0.3

Position (m) Position (m)

Figure 12: Temperature profiles at 109 mm downstream of quarl

... --- . .... _---_ ........... -........... . .. -.

2.4<»+CO

2.2o..CO

1.80..CO

Static Temperature 1.so..CO

(k)

1.40..CO

l.2o..CO

0.4 0.5 0.6

· ...

0.4 0.5 0.6

· ...

1.l'.'"-<O+---,.....----.----r---...-----..---. 1.00..CO+--_,.....----.-__ -r-__ ...--_--.. __ ....,

(I 0.1 0.2 0.3 0.4 0.5 0.6 0.1 02 0.3 0.4 0.5 0.6

Position (m) Position (m)

Figure 13: Temperature profiles at 343 mm downstream of quarl

12

Figure 14: Contot,rs showing temperature variation in burner

1.61.'oe+(Il

cty-mole-02 U\''oe+(I1 dry-mole-co2

........ .. . .. .

a'~+-~~-----r----T---~----~--~ (I 0.1 0.2 0.3 0.4 0.5 0.6 0.1 0.2 0.3 0.4 0.5 0.6

Position (m) Position (m)

Figure 15: O2 and CO 2 profiles at 27 mm downstream of quarl

13

t " ~NT

1.400>+01 9.0<»+00

1.200>+ 01 8.0<»+00

1.0<»+01 7.0<»+00

dry-mole-02 8.0<»+00 jry-mole-co2 6.0<»+00

5.0<»+00 4.0<»+00

2.00..00 4.0<»+00

0.0<»+00 +-0:::..._..--_--.,........._--.. __ -.-__ ....-_--. 3 .0<»+00 +---.-----.----..---.---........ --... 0.1 0.2 0.3 0.4 0.5 0.6 0.1 0.2 0.3 0.4 0.5 0.6

Position (m) Position (m)

Figure 16: O2 and CO2 profiles at 109 mm downstream of quarl

1.100>+01

1.os...01

1.0<»+01

95 00>+00

9.0<»+00

dry-mole-02 5.(\. ...... ro jry-mole-co2 85 00>+00

8.0<»+00

2.~ ...... ( .... 75 00>+00

7.0<»+00

(\.(\.-..oo +--'--.-----...----..---.---........ ---. 6500>+00 +----":,.----.----..--....,...--........ ---, (\ 0.1 0.2 0.3 0 .4 0.5 0.6 o 0.1 0.2 0.3 0.4 05 0.6

Position (m) Position (m)

Figure 17: O2 and CO2 profiles at 343 mm downstream of quarl

14

- - - UNS-Mag-2ste - ·UNS-Mag-1 ste . Experiment -lldf 2.00e-01

1.75e-01

1.50e-01

1.25e-01

1.00e-01

dry-mole-02 7.50e-02

5.009-02 .... ~ -

.,- ---.-. = .......... -........ ---.............. - ....... - ........ -........ -.. ~.~ .. -. ...... -.-. 2.509-02

O.OOe+OO

·2.50e·02

0 0.1 0.2 0.3 0.4 0.5 0.6

Position (m)

Figure 18: O2 profiles at 27 mm downstream of quarl

_ •• UNS·Mag·2ste - ·UNS-Mag·1ste . experiment -pdf 1.40e·01

1.20e-01

1.00e·01 ........ ----_ ... .. -_ ........ -------_ ..... _--_ ...... .

8.00e-02

dry-mole-co2 6.00e-02

4.00e-02

2.00e-02

O.OOe+OO

0 0.1 0.2 0.3 0.4 0.5 0.6

Position (m)

Figure 19: CO 2 profiles at 27 mm downstream of quarl

15