Upload
leduong
View
222
Download
0
Embed Size (px)
Citation preview
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
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
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
Experimental Apparatus: PARAT Burner
4
Lower plate
Upper plate
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
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
7
Large Eddy Simulations
Instantaneous Temperature [K]
Mean Temperature [K]
Computational Grid
Region: 5 < y/d < 6
8
Inlet Boundary Conditions LES Comparison with Experiments
Non reacting flow simulation for jet velocity profiles at the burner exit
Flame 1 velocity contour
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′ ′ + ∆
∆ = ∆ = −′
10
LES Mean Temperature Contours on Z=0 Plane
Cent
erlin
e
MeanTemperature (K)
11
Axial Temperature Profiles with CO2 Addition
0% CO2 5% CO2 10% CO2
12
Cent
erlin
e
LES RMS Temperature on Z=0 plane
RMSTemperature (K)
13
0% CO2 5% CO2 10% CO2
T_RMS comparison between CARS and LESCenterline RMS temperature
14
Temperature comparison between CARS and LES
MeanTemperature (K)
CARS measurements
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
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!
17
OH PLIF video for flame with 0% CO2 addition
Hydrogen pilot flame
Φ=0.8, Re=10000
18
OH PLIF video for flame with 5% CO2 addition
Hydrogen pilot flame
Φ=0.84, Re=10000
19
OH PLIF video for flame with 10% CO2 addition
Hydrogen pilot flame
Φ=0.89, Re=10000
20
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
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
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 <x/D<6.5Radial flame brush development Axial flame brush development
23
Global Consumption Speed
�𝒄𝒄 = 𝟎𝟎.𝟐𝟐𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄𝒄
[ ]
2
, 21 2 ( 0.2) /T GC
USx c D
=+ =
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
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
upA Unburned pocket area
t∆ Time step
26
CH PLIF: Wavelength & Signal Strength
Simulation using LIFBASE
CH
OH
27
CH PLIF video for flame with 0% CO2 addition
Hydrogen pilot flame
Φ=1, Re=10000
28
CH PLIF video for flame with 5% CO2 addition Φ=1, Re=10000
Hydrogen pilot flame
29
CH PLIF video for flame with 10% CO2 addition Φ=1, Re=10000
Hydrogen pilot flame
30
CH-OH PLIF video for flame with 0% CO2 addition
Hydrogen pilot flame
Φ=1, Re=10000
31
CH-OH PLIF video for flame with 5% CO2 addition Φ=1, Re=10000
Hydrogen pilot flame
32
CH-OH PLIF video for flame with 10% CO2 addition Φ=1, Re=10000
Hydrogen pilot flame
33
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
34
IR imaging video for CH4/air flame
Φ=0.8, Re=10000
35
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
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 dλ
λ λ λλ λ ττ τ τ
λ λ λ λ λ λλ λα λ α τ τ λ
∗− − −∗ ∗= +∫ ∫ ∫
37
Temperature Deconvolution
Computed temperature vs thin filament thermometry
Computed temperature vs CARS thermometry
38
Re=100,000, Φ=0.80
H2 Pilot, 6% HR
5 bar, Tinlet590 K
High Pressure PARAT Experiments and LES
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
40
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
41
Cold flow Results with RANS based RNG k-Ԑ model
Good Agreement with Hot wire anemometer measurements
Appendix
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
Appendix