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Effects of Exhaust Gas Recirculation (EGR) onTurbulent
Combustion Emissions in Advanced Gas Turbine
Combustors with High Hydrogen Content (HHC) Fuels
Jay P. Gore and Robert P. Lucht, Purdue University
Maurice J. Zucrow LaboratoriesSchool of Mechanical
Engineering
Purdue UniversityWest Lafayette, IN
DOE Award No. DE-FE0011822
National Energy Technology LaboratoryUniversity Turbine Systems
Research Program
Project Review Meeting November 1-2, 20171
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Collaborations
Yiguang Ju and Michael Mueller – PrincetonGaurav Kumar and Scott
Drennan – Convergent Sci. Inc. NewBraunfels, TexasJeff Moder – NASA
Glenn Research CenterRelated Sponsors – FAA, ONR, Rolls Royce,
Siemens, GE
PhD students
Dong Han – CARS and PLIFHasti Veeraraghava Raju - CFD
simulationsJupyoung Kim – PIV
Post Doctoral Associate : Aman Satija
DOE Program Manager: Mark Freeman
Acknowledgments
2
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Content1. Piloted Axisymmetric Reactor Assisted Turbulent
(PARAT) burner
development and testing under atmospheric and high-pressure
conditions
2. Effects of CO2 addition on turbulent flame structure and
burning velocity
3. Temperature and velocity measurements in CH4 /air/CO2 flames
with different levels of CO2 addition using CARS and PIV
4. Development and validation of LES model for H2 piloted
CH4/air/CO2 premixed turbulent flames
5. CH PLIF and IR imaging for turbulent premixed flames3
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Experimental Apparatus: PARAT Burner
4
Lower plate
Upper plate
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Flames with varying levels of CO2 addition
10% CO2, Φ=0.89 5% CO2, Φ=0.84 0% CO2, Φ=0.80
Re=10,000, Tad=2030 K, Le=1, P=1 bar
Flames designed to minimize thermal and transport effects on
NOx
5
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Large Eddy Reacting Flow Simulations
• Premixing tube simulated separately and the solutions
patched
• Jet Reynolds number – 10000 • Domain (D= 18 mm): 36D x 64D x
36 D• Detailed chemistry solver with DRM19 mech.
Turbulence – 1 eq. dynamic structure model• Sensitivity study
with base grid : 10 x 8 x 6 mm • 4 Level Adaptive Mesh Refinement
based on
Velocity and Temperature, Max. 15 M cells• Mesh sensitivity
studied with Max. 30 M cells
Burner surface
CH4+Air (Premixed)
Pilot H2Pilot H2
Y
X
Z
• DRM19 Mechanism: (http://combustion.berkeley.edu/drm/)•
Elements : O, H, C, N, AR• Species: H2, H, O, O2, OH, H2O, HO2,
CH2, CH2(S), CH3, CH4,
CO, CO2, HCO, CH2O, CH3O , C2H4, C2H5, C2H6, N2, AR• Number of
Reactions: 84
Z=0 PlaneMesh
Chemistry
CFD Summary
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7
Large Eddy Simulations
Instantaneous Temperature [K]
Mean Temperature [K]
Computational Grid
Region: 5 < y/d < 6
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8
Inlet Boundary Conditions LES Comparison with Experiments
Non reacting flow simulation for jet velocity profiles at the
burner exit
Flame 1 velocity contour
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Boundary Condition & Turbulence Intensity at x/D=0.2
Mean & RMS velocity profiles
Integral length scale &turbulence intensity
9
Turbulence intensity. . rms
mean
uT Iu
=
Integral length scale
0( ) ( , *) *l r r r drρ
∞= ∫ 2
( ) ( )( , ) ; | * |( )
x x
x
u r u r rr r r r ru r
ρ′ ′ + ∆
∆ = ∆ = −′
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10
LES Mean Temperature Contours on Z=0 Plane
Cent
erlin
e
MeanTemperature (K)
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11
Axial Temperature Profiles with CO2 Addition
0% CO2 5% CO2 10% CO2
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12
Cent
erlin
e
LES RMS Temperature on Z=0 plane
RMSTemperature (K)
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13
0% CO2 5% CO2 10% CO2
T_RMS comparison between CARS and LESCenterline RMS
temperature
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14
Temperature comparison between CARS and LES
MeanTemperature (K)
CARS measurements
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15
At y/d =5
At y/d =1.94
0% CO2 10% CO2
At y/d =5
At y/d =1.94
Temperature comparison between CARS and LESRadial mean and RMS
temperature
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Thin or Purely Wrinkled Flame Assumption is not adequate!
CO2levels
Characteristic flame
thickness, λ(μm)
Kolmogorov length scale
η, (μm)
0% 70 50
5% 80 52
10% 90 55
0u
L
DS
λ =1/43νη
ε
=
16
RMS max mean mean minT = (T -T )(T -T )
Effect of CO2 on the chemistry of turbulent flames with EGR are
captured in the present computations!
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17
OH PLIF video for flame with 0% CO2 addition
Hydrogen pilot flame
Φ=0.8, Re=10000
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OH PLIF video for flame with 5% CO2 addition
Hydrogen pilot flame
Φ=0.84, Re=10000
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OH PLIF video for flame with 10% CO2 addition
Hydrogen pilot flame
Φ=0.89, Re=10000
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OH PLIF Images & Data Processing
0% CO2 5% CO2 10% CO2Products𝒄𝒄= 𝟏𝟏
Reactants𝒄𝒄= 𝟎𝟎 1
( )1( )
ni
i i
L cn A c=
Σ = ∑Flame surface density
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21
Mean Reaction Progress
( )1/2
1/2,
'2 ' 1 1 exp'T rl uu l
u lτδ α τ
τ = − − −
Axial direction
Radial direction
Flame brush development & Taylor’s theory
1
1( , ) ( , )n
ii
c x r c x rn =
= ∑Mean progress variable
1, maxT r
dcdr
δ − = Data
Fit
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22
Flame Surface Density
1
( )1( )
ni
i i
L cn A c=
Σ = ∑Mean flame surface density
0 < x/D < 3.6 3.6
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23
Global Consumption Speed
�𝒄𝒄 = 𝟎𝟎.𝟐𝟐𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄
[ ]
2
, 21 2 ( 0.2) /T GC
USx c D
=+ =
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24
Local Consumption Speed
w/o pockets
w/ pockets
• w/o pockets
• w/ pockets
• pockets
, 0 0T
T LC LL
AS S IA
=
, 0 0 maxT LC L TS S I δ= Σ
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25
Fine-scale Unburned Pocket Consumption
Fine-scale pocket size Consumption speed
, 2up
T LCPe
AS
R tπ∆
=∆
upe
AR
π=
Fine-scale pocket: a pocket does not break up into smaller ones
with flame-flame interaction
upAUnburned pocket area
t∆ Time step
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26
CH PLIF: Wavelength & Signal Strength
Simulation using LIFBASE
CH
OH
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27
CH PLIF video for flame with 0% CO2 addition
Hydrogen pilot flame
Φ=1, Re=10000
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CH PLIF video for flame with 5% CO2 addition Φ=1, Re=10000
Hydrogen pilot flame
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29
CH PLIF video for flame with 10% CO2 addition Φ=1, Re=10000
Hydrogen pilot flame
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30
CH-OH PLIF video for flame with 0% CO2 addition
Hydrogen pilot flame
Φ=1, Re=10000
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31
CH-OH PLIF video for flame with 5% CO2 addition Φ=1,
Re=10000
Hydrogen pilot flame
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CH-OH PLIF video for flame with 10% CO2 addition Φ=1,
Re=10000
Hydrogen pilot flame
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CH PLIF & Simultaneous CH and OH PLIF
0% CO2 5% CO2 10% CO2
(a) wrinkled flame front, (b) unburned reactant pocket.
Φ=1, Re=10000 Green: CH Layer Blue: OH Zone
Challenging for lean premixed flames with CO2 dilution due to
low CH signal
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34
IR imaging video for CH4/air flame
Φ=0.8, Re=10000
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Instantaneous IR images
2.58±0.03 μm 2.77 ± 0.1 μm 4.38 ± 0.08 μmH2O H2O+CO2 CO2
0% CO2 10% CO2
Multiple bandpass filters with KC burner Varying CO2 with PARAT
burner
CH4/air Φ=0.80 Re=10000 Re=10000
Φ=0.80 Φ=0.89
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36
Time Averaged Radiation Model Validation
Turbulence radiation interaction (TRI) modeling:
Stochastic time and space series analysis (STASS)
2 2
1 1
( )
0(0) ( )bI I e d I e d d
λλ λ λ
λ λ ττ τ τλ λ λ λ λ λλ λ
α λ α τ τ λ∗− − −∗ ∗= +∫ ∫ ∫
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37
Temperature Deconvolution
Computed temperature vs thin filament thermometry
Computed temperature vs CARS thermometry
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Re=100,000, Φ=0.80
H2 Pilot, 6% HR
5 bar, Tinlet590 K
High Pressure PARAT Experiments and LES
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39
Summary & Conclusions1. Developed a PARAT burner and
demonstrated multiple diagnostic methods including PIV, CARS, OH/CH
PLIF and IR imaging for turbulent premixed combustion
applications.
2. Performed a comprehensive investigation of the non-thermal
effects of CO2 addition on turbulent premixed combustion for the
first time.
3. CO2 addition extends flame length, Modifies flame brush to be
longer and thinner, alters local flame surface area, reduces
burning velocities, and enhances pocket formation with negligible
effects on pocket consumption speed
4. Developed LES simulation tool for CH4/air/CO2 flames and
validated using temperature and velocity measurements
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Flame # 1 2 3
Reynolds number (± 50) 10000
Adiabatic Temperature (± 50 K) 2030
Equivalence ratio (± 0.02) 0.80 0.84 0.89
CO2 % by total mass (± 0.1) 0.0 5.0 10.0
CH4 mass flow rate (± 2 mg/s) 111 110 109
Air mass flow rate (± 20 mg/s) 2440 2300 2150
CO2 mass flow rate (± 4 mg/s) 0.00 124 246
Pilot H2 mass flow rate (± 0.03 mg/s) 2.7
Pilot H2 heat release percent of total (%) 6
Lewis number 1
Laminar flame speed (cm/s) 34 30 25
Laminar flame thermal thickness (µm) 70 80 90
RMS turbulence fluctuation (m/s) 1.7
Integral length scale (mm) 1
Appendix Flame operating conditions
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41
Cold flow Results with RANS based RNG k-Ԑ model
Good Agreement with Hot wire anemometer measurements
Appendix
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42
Davidson et.al, IJHF, 27, 2006
Nozzle Exit: Specified mean velocity profile. Turbulent
Fluctuations: Random Fourier Approach
Burner surface
CH4+Air (Premixed)
Pilot H2Pilot H2
Outflow Boundary
CFD Domain and BCs - Reacting
Premixing Tube Excluded to Reduce Computational Time
36D x 64D x 36D, D= 18 mm
Y
XZ
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