NUMERICAL ANALYSIS OF HOT JET INJECTION AND PREMIXED FLAME PROPAGATION IN A CHANNEL Dhruv Baronia...
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Transcript of NUMERICAL ANALYSIS OF HOT JET INJECTION AND PREMIXED FLAME PROPAGATION IN A CHANNEL Dhruv Baronia...
NUMERICAL ANALYSIS OF HOT JET INJECTION NUMERICAL ANALYSIS OF HOT JET INJECTION AND PREMIXED FLAME PROPAGATION IN A AND PREMIXED FLAME PROPAGATION IN A
CHANNELCHANNEL
Dhruv BaroniaDhruv BaroniaGraduate Research AssistantGraduate Research Assistant
Department of Mechanical EngineeringDepartment of Mechanical EngineeringPurdue School of Engineering and Technology, IUPUIPurdue School of Engineering and Technology, IUPUI
Graphics: Rolls RoyceGraphics: Rolls Royce Source: ABBSource: ABB
Source: NASASource: NASA
Purdue School of Engineering and Technology, Indianapolis, IN
● Design of Experiment (DOE)
● Numerical Simulations Using Star-CD
OutlineOutline
●Single Channel Test Rig
● Conclusions and Recommendation
● Motivation
Purdue School of Engineering and Technology, Indianapolis, IN
MotivationMotivation
High cost of experiments
Guide future experiments on Single Channel Rig for efficient data collection
Optimize wave rotor performance
Purdue School of Engineering and Technology, Indianapolis, IN
IUPUI Single-Channel Internal Combustion Wave Rotor
Premixed
Chamber
Supersonic Injection Nozzle
Pyrex Window
Purdue School of Engineering and Technology, Indianapolis, IN
Previous Experimental ResultsPrevious Experimental Results
Purdue School of Engineering and Technology, Indianapolis, IN
Numerical Simulation in Single Channel Numerical Simulation in Single Channel Test Rig With Star-CDTest Rig With Star-CD
Star-CD is a commercial Computational Fluid Dynamics (CFD) code
It is a finite-volume solver and is selected because of relatively advanced modeling of transient and propagating combustion phenomena
It is a pressure-based solver hence it is not expected to capture shock waves sharply
Used extensively in IC engine and gas turbine combustion simulations
Purdue School of Engineering and Technology, Indianapolis, IN
Combustion ModelingCombustion Modeling
Hundreds of elementary reactions
Simplified models to predict overall temperature, pressure and enthalpy changes
Reaction rates determined by both mixing and kinetics
Purdue School of Engineering and Technology, Indianapolis, IN
Numerical Combustion ModelingNumerical Combustion Modeling
Computation Cellflame front
averaged thermodynamic, species and turbulence values
turbulent flame thickness ~ 0.3mm
burnedunburned
minimum cell size 0.5mm
Purdue School of Engineering and Technology, Indianapolis, IN
Single Channel Test Rig Simulation: Single Channel Test Rig Simulation: Geometry And Grid For NumericalGeometry And Grid For Numerical
A 2D geometry is created to preserve the volume ratio to maintain realism of mass, energy and pressure history
Purdue School of Engineering and Technology, Indianapolis, IN
Body fitted grid with refinement near the boundary and in the shear layer
Single Channel Test Rig Simulation: Single Channel Test Rig Simulation: Geometry And Grid For NumericalGeometry And Grid For Numerical
Purdue School of Engineering and Technology, Indianapolis, IN
Initial ConditionsInitial ConditionsThermodynamic Properties and
Mass FractionTest Cell Prechamber
Equivalence Ratio (prior to burn) 1.34 1.5
Propane 0.079096 0.0219
Oxygen 0.214663 0.0
Carbon Dioxide 0.0 0.1759
Water Vapor 0.0 0.0957
Nitrogen 0.706241 0.6994
Pressure (abs, Pa) 1.0E05 8.4E05
Temperature (K) 298 1950
Turbulence Kinetic Energy (m2/s2) 0.0 0.0
Eddy Dissipation (m2/s3) 0.0 0.0
Purdue School of Engineering and Technology, Indianapolis, IN
Combustion ModelsCombustion Models
One-step combustion reaction with combined (kinetic & turbulent) time scale model
Four-step combustion reaction [Glassman] based on pure kinetics
Four-step combustion reaction [Glassman] with hybrid reaction modeling
Purdue School of Engineering and Technology, Indianapolis, IN
One-Step Reaction With Combined Time One-Step Reaction With Combined Time ScaleScale
Reaction time scale is a sum of turbulence time and kinetic time
Activation energy, pre-exponent factor, etc. are calculated by Westbrook and validated for laminar flames
Model will not predict ignition delay time
Purdue School of Engineering and Technology, Indianapolis, IN
Baroclinic EffectBaroclinic Effect
grad p
Incident shock wave
ρ2 ρ1 ρ2 > ρ1
grad ρ
grad ρ
Interface
vorticity
I
II
III
Initial configuration
Vorticity generation
Deformation
Purdue School of Engineering and Technology, Indianapolis, IN
Results for One-Step Reaction With Combined Results for One-Step Reaction With Combined TimeTime
Acceleration and stretching of the flame front on interaction with shock wave
Some amount of fuel/air mixture is left unburned at the left end of the channel
Purdue School of Engineering and Technology, Indianapolis, IN
Comparison With Non-reacting CaseComparison With Non-reacting Case
Pressure wave moving ahead
Stretching of the flame front due to baroclinic effect
No Combustion
Combustion
Purdue School of Engineering and Technology, Indianapolis, IN
Baroclinic Effect on Reacting and Non-Baroclinic Effect on Reacting and Non-Reacting CasesReacting Cases
Combustion No combustionexp(grad ρ)
exp(grad p)
Density gradient
Pressure gradient
combustion front
shock wave
Purdue School of Engineering and Technology, Indianapolis, IN
Combustion EffectsCombustion Effects
higher mass injection in no combustion case
Purdue School of Engineering and Technology, Indianapolis, IN
Four-Step Reaction Four-Step Reaction
OHOH
COOCO
HCOOHC
HHCHC
222
22
2242
24283
2
12
1
222
3
OHOH
COOCO
HCOOHC
HHCHC
222
22
2242
24283
2
12
1
222
3
OHOH
COOCO
HCOOHC
HHCHC
222
22
2242
24283
2
12
1
222
3
OHOH
COOCO
HCOOHC
HHCHC
222
22
2242
24283
2
12
1
222
3
Initiation
Propagation
Oxidation
Oxidation
Purdue School of Engineering and Technology, Indianapolis, IN
Four Step ReactionFour Step Reaction
4444
3333
1222
1111
][][])[/exp(10][
)48.2exp(93.7][][])[/exp(10][
][][])[/exp(10][
][][])[/exp(10][
422242
223
83242242
42283183
cbax
cbax
cbax
cbax
HCOHRTEdt
Hd
OHOCORTEdt
COd
HCOHCRTEdt
HCd
HCOHCRTEdt
HCd
1 2 3 4
x 17.32 14.7 14.6 13.52
Ea/R (K) 24962 25164 20131 20634
a 0.5 0.9 1.0 0.85
b 1.07 1.18 0.25 1.42
c 0.4 -0.37 0.50 -0.56
Note: negative exponent
Purdue School of Engineering and Technology, Indianapolis, IN
Validation of Four-Step ReactionValidation of Four-Step Reaction
Geometry: 5X5X5 cells with symmetry boundary on all sides
Initial Conditions: p=1 atm, T=1200 K, φ=1.34
Purdue School of Engineering and Technology, Indianapolis, IN
ResultsResults
0
0.02
0.04
0.06
0.08
0.1
0.12
0 1 2 3 4 5 6 7 8
Time(ms)
Mas
s F
ract
ion
C3H8 C2H4 H2 CO CO2 H2O O2/3 Temperature/20000
Purdue School of Engineering and Technology, Indianapolis, IN
ObservationsObservations
Ignition delay time of 6.2 ms which is in good agreement with experimental data
Dissociation of propane is endothermic
Oxidation of hydrogen takes place at all temperatures
All propane is dissociated in ethylene
Purdue School of Engineering and Technology, Indianapolis, IN
ResultsResults
Geometry, BCs and ICs (expect for φ=1.34 in test cell) are similar to the previous one step reaction
Reflected shock wave initiates autoignition resulting in further compression waves to complete the combustion
Purdue School of Engineering and Technology, Indianapolis, IN
Key IssuesKey Issues
One-step global reaction is too coarse assumption Four-step reaction (pure kinetics) is able to simulate low
temperature chemistry before ignition, which is purely based on kinetics
Four-step reaction (kinetics + turbulence mixing) includes the influence of turbulence and can model the
turbulent flame propagation after auto-ignition
These inferences call for a hybrid reaction model that can switch between pure kinetics and
combined time (kinetics + turbulence mixing)
Purdue School of Engineering and Technology, Indianapolis, IN
Hybrid Reaction ModelHybrid Reaction Model
For (T < Tign) Use reaction rates (for all four reactions) based on kinetics
For (T > Tign) Reaction time scale is a sum of kinetic time scale and turbulent
mixing time scaletlc f
Where ‘ f ’ (0.0 < f < 1.0) is a delay constant that simulates the influence of turbulence on combustion after ignition [Kong]
632.0
1 ref
species reactive total
products ofamount r
The choice of Tign is arbitrary and some experimentation will be required
Purdue School of Engineering and Technology, Indianapolis, IN
Hybrid Reaction Model: Initial ConditionsHybrid Reaction Model: Initial Conditions Hybrid model I : Tign=1200 K
Hybrid model II : Tign=1500 K Initial conditions inside the prechamber is calculated using mole balance and water
gas shift reaction
Thermodynamic Properties and Mass Fractions Test Cell Prechamber
Equivalence Ratio (prior to burn) 1.0 1.5
Propane 0.0624 0.0
Oxygen 0.219 0.0
Carbon Dioxide 0.0 0.0834
Water Vapor 0.0 0.0973
Nitrogen 0.7186 0.69965
Ethylene 0.0 1.0E-18
Hydrogen 0.0 0.00515
Carbon Monoxide 0.0 0.1145
Pressure (abs, Pa) 1.0E+05 8.4E+05
Initial Turbulence Kinetic Energy (m2/s2) 0.0 0.0
Purdue School of Engineering and Technology, Indianapolis, IN
Propane Mass Fraction ContoursPropane Mass Fraction Contours
Tign = 1200 K Tign = 1500 K
Stretching of flame front
Purdue School of Engineering and Technology, Indianapolis, IN
Temperature ContoursTemperature Contours
Tign = 1200 K Tign = 1500 K
Purdue School of Engineering and Technology, Indianapolis, IN
Ethylene Mass Fraction ContoursEthylene Mass Fraction Contours
No oxygen in this region
Purdue School of Engineering and Technology, Indianapolis, IN
Propane Consumption PlotsPropane Consumption Plots
0.00E+00
5.00E-08
1.00E-07
1.50E-07
2.00E-07
2.50E-07
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Time (ms)
Rat
e o
f p
rop
ane
con
sum
pti
on
(kg
/ms)
Tign = 1200K
Tign = 1500K
5.00E-07
5.50E-07
6.00E-07
6.50E-07
7.00E-07
7.50E-07
8.00E-07
8.50E-07
9.00E-07
9.50E-07
1.00E-06
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Time (ms)
Pro
pan
e M
ass
(kg
)
Tign = 1200K
Tign = 1500K
Purdue School of Engineering and Technology, Indianapolis, IN
Hybrid Reaction Model: ResultsHybrid Reaction Model: Results
With the 1500K threshold temperature ignition occurs as soon as the hot gas jet mixes with cold gas whereas with 1200K threshold temperature it happens upon second compression by the reflected shock wave
Hybrid model II shows the stretching of the flame front due to baroclinic effect
In hybrid model II, the peak pressure inside the test channel is about 2 atmospheres higher and average pressure is about 1.5 atmospheres higher
Purdue School of Engineering and Technology, Indianapolis, IN
Key IssuesKey Issues
Two model options predicted different combustion behavior
Effects of equivalence ratio and initial turbulence are not evaluated
Purdue School of Engineering and Technology, Indianapolis, IN
Design of Experiment (DOE)Design of Experiment (DOE)
DOE is a statistical method to do the numerical experiments
DOE provides information about the interactions of parameters and shows how parameters affect the combustion model
Box Behnken Model: Individual and Combined effect of design parameters
Purdue School of Engineering and Technology, Indianapolis, IN
DOE :Design and model parametersDOE :Design and model parameters
Design Parameter Low Value Mid Value High Value
Equivalence Ratio 1.0 1.17 1.34
Initial Turbulence Kinetic Energy (m2/s2) 0.0 1125 2250
Threshold Temperature (Tign , K) 1200 1350 1500
Purdue School of Engineering and Technology, Indianapolis, IN
Propane Consumption PlotsPropane Consumption Plots
Different Ignition delay
Purdue School of Engineering and Technology, Indianapolis, IN
DOE : ResultsDOE : Results
Purdue School of Engineering and Technology, Indianapolis, IN
DOE: ResultsDOE: Results
t = 0.5ms
t = 1.0ms
t = 2.0ms
Purdue School of Engineering and Technology, Indianapolis, IN
Conclusion and RecommendationsConclusion and Recommendations
Combustion regimes inside the channel is studied numerically using available combustion models
Hybrid model is proposed which was able to predict autoignition and subsequent turbulent flame propagation
Hybrid model was found to be more sensitive to model parameter Tign
Purdue School of Engineering and Technology, Indianapolis, IN
Conclusion and RecommendationsConclusion and Recommendations
Hybrid model needs further development to be predictive of combustion effects
Suggested model parameter: entropy
Purdue School of Engineering and Technology, Indianapolis, IN
PublicationsPublications
Akbari P., Baronia D., Nalim M. R., 2006, “Single-Tube Simulation of a Semi-Intermittent Pressure-Gain Combustor”, appears in ASME Turbo-Expo 2006, GT-2006_91061
Purdue School of Engineering and Technology, Indianapolis, IN
AcknowledgementAcknowledgement
Department of Mechanical Engineering, IUPUI
Computer Network Center
CD-Adapco
Colleagues and friends
Purdue School of Engineering and Technology, Indianapolis, IN
Thank you …Thank you …
Questions?Questions?