Nonequilibrium Thermodynamics Laboratories The Ohio State University Nonequilibrium Gas Dynamics: Understanding of High-Speed Flows at Strong Energy Mode Disequilibrium Igor V. Adamovich Seminar at the Department of Aeronautical Engineering January 28, 2008
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Nonequilibrium Thermodynamics Laboratories The Ohio State University
Nonequilibrium Gas Dynamics: Understanding of High-Speed Flows
at Strong Energy Mode Disequilibrium
Igor V. Adamovich
Seminar at the Department of Aeronautical Engineering
January 28, 2008
Nonequilibrium Thermodynamics Laboratories The Ohio State University
NETL Group
Faculty:
Igor Adamovich, Walter Lempert, Bill Rich, Vish Subramaniam
Post-docs:
Naibo Jiang, Evgeny Mintusov, Munetake Nishihara, Anna Serdyuchenko
Students:
Sherrie Bowman, John Bruzzese, Inchul Choi, Ashim Dutta, Saurabh Keshav, Mruthunjaya Uddi, Matt Webster, Yvette Zuzeek
Nonequilibrium Thermodynamics Laboratories The Ohio State University
• Generation and sustaining of stable high-pressure weakly ionized plasmas
• High-speed flow control by nonequilibrium plasmas / MHD
• Ignition, combustion, and flameholding by nonequilibrium plasmas
• Molecular gas lasers
• Kinetics of gases, plasmas, and liquids at extreme thermodynamicdisequilibrium
• Molecular energy transfer processes: excitation and relaxation of vibrationaland electronic levels, chemical reactions among excited species, plasmaradiation
• Electron and ion kinetics: ionization, recombination, electron attachmentand detachment, charge transfer, inelastic electron-molecule collisions
• Flow visualization and optical diagnostics
Scope of Research
Nonequilibrium Thermodynamics Laboratories The Ohio State University
NETL: Major Research Projects ($11M since 1997)
“Air Plasma Ramparts Using Metastable Molecules” (AFOSR MURI ′97-′02)
“Anomalous Shock Wave Propagation and Dispersion in Weakly Ionized Plasmas”(AFOSR ′99-′01, NASA ′99-′00)
“Effect of Vibrational Nonequilibrium on Electron Kinetics in High Pressure Molecular Plasmas” (NSF/DOE, ′00-′06)
(AFRL/DAGSI, ′01-′03) “Non-Thermal Ignition Phenomena for Aerospace Applications”
“Generation and Characterization of Stable, Weakly Ionized Air Plasmas in Hypersonic Flows” (AFRL/DAGSI, ′01-′03)
“Energy Transfer Rates and Mechanisms for Hypervelocity Vehicle Radiation” (AFOSR, ′01-′07)
“Effect of MHD Forces on Stability and Separation of Nonequilibrium Ionized Supersonic Flow” (AFOSR, ′02-′04)
“Plasma Flow Control Technology for Hypersonic Boundary Layer Transition Control” (AFRL, ′02-′05)
“Instrumentation for Generation and Optical Diagnostics of Repetitively Pulsed Fast Ionization Wave Plasmas in Supersonic Flows” (AFOSR DURIP, ′05-′06)
“Active Control of Jet Noise Using Plasma Actuators” (NASA ′02, ′05-′06, with GDTL)
“Electric Discharge Oxygen-Iodine Laser Operating at High Pressure” (JTO, ′06-′08)
“Kinetic Studies of Plasma Assisted Combustion By Non-Equilibrium Discharges” (AFOSR, ′07-′09)
“Nonequilibrium Ignition and Flameholding in High-Speed Reacting Flows” (NASA, ′07-′09)
“Supersonic Jet Noise Suppression Using Plasma Actuators” (NASA ′07-′09, with GDTL)
“Nonequilibrium Gas Dynamics” (AFOSR ′08-′10)
Nonequilibrium Thermodynamics Laboratories The Ohio State University
NETL Research in Broader Context:National Hypersonic Basic Research Plan (AFOSR, NASA, SNL)
Thrust Areas
• Boundary Layer Physics
• Nonequilibrium Flows*
• Shock-Dominated Flows
• Environment-Material Interactions
• High-Temperature Materials
• Supersonic Combustion*
* studied in NETL
Nonequilibrium Thermodynamics Laboratories The Ohio State University
• TPS Design: Current uncertainties for reacting air (andother gases) at re-entry and cruise create estimated factor oftwo errors in predicting heat load and designing leadingedges, TPS
• Aerodynamic Control: High-altitude aerodynamicsincluding pitching moments and reaction controlsystems/surfaces not predictable. Wake heating and largeangle-of-attack flows not predictable
Critical System Impact of Nonequilibrium Hypersonic Flows
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Temperature behind a 12 km/sec shockpredicted by SOA model is not even closeto experiment (in pure nitrogen!)
Matsuda et al, JTHT, 2004
Basic research vision for the next 30 years must include development andvalidation of design tools that simulate hypersonic vehicleaerothermodynamics and propulsion
Static temperature and NO fractionpredicted by SOA model in a M=15expansion “air” flow are off.
Experiment: LENS, M=15, run time~1 msec
Candler et al, AIAA Paper, 2007
How Good is the Current State of the Art (SOA)?
Experiment ModelFlow velocity, m/s 4517 4354Temperature, K 250-300 620NO fraction, % 1.5 5.4
We have a problem (might be both with experiment and modeling)
Nonequilibrium Thermodynamics Laboratories The Ohio State University
• Due to shock waves, boundary layers, or rarefaction, concept of singletemperature breaks down, fluid dynamic equations break down,chemistry is not well understood
• Understanding / predicting these flows requires insight into molecular /surface / radiation / plasma interactions
• Four interacting research areas:
Key Challenges
Need to predict nonequlibrium hypersonic flows based on sound physics, not extrapolations of measurements or empirical correlations
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Foster development of both technical and human resources for theexploration, characterization and control of flows at high Machnumbers with significant thermochemical nonequilibrium.
• Development of validated physics-based tools for prediction ofheating, aerodynamics, etc of hypersonic system
• Transfer of proven, physics-based models and simulation methodsand complementary technical expertise to industry and appliedresearch
• Development and maintenance of essential human resources tocapitalize on and continue progress in this area.
Strategic (Long Term) Goals
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Near term (<5 years):• Measure key air reaction rates and mechanisms at higher temperatures• Develop improved catalytic wall-boundary condition for hypersonic flow with
typical surface• Plan, design, fund facilities for well-characterized reacting hypersonic flow data• Obtain ground and/or flight data with spectral, species, or spatially-resolved
reacting hypersonic flow. Utilize/coordinate with NATO RTO results
Mid-term (5-10 years):• Measure / accurately calculate all important atmospheric (earth/other) gas
reactions at ultra-high temperatures• Validate advanced ultra-high temperature models for excited states, relaxation,
surface collisions, catalysis, ablation• Complete integrated radiation transport models; accurate ultra-high
temperature gas transport properties• Well-characterized reacting hypersonic flow data using advanced diagnostics• Fast CFD and kinetic simulation tools with integrated physics models
Objectives Defined by Nonequilibrium Thrust Panel at NASA / Air Force Workshop, June 2007
Nonequilibrium Thermodynamics Laboratories The Ohio State University
NETL Contribution: Outline
I. Ability to generate and sustain steady-state supersonic flows withstrong energy mode disequilibrium and targeted energy loading
II. In-depth flow characterization using advanced optical diagnostics
III. Physics-based, validated molecular energy transfer andnonequilibrium chemical reaction models
IV. New research program: characterization of nonequilibriumsupersonic flows, developing instrumentation for use at a nationalhypersonic facility (LENS)
V. Future research thrusts
Nonequilibrium Thermodynamics Laboratories The Ohio State University
A Bit of History: Shock Weakening by Weakly Ionized Plasmas
Ballistic range / glow discharge experiments
(Russia, 1980’s; U.S., 1990’s)
• shock stand-off distance increases
• wave drag reduction up to 50%
Suggested Interpretations
• vibrational relaxation
• ion-acoustic wave
• nonuniform heatingBow shock around a sphere. Air, P=9.5 torr, u=1600 m/s (AEDC, 1999)
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Case 1: Steady State Plasma Shock Experiment
Aerodynamically Stabilized DC Glow Discharge
Transverse RF discharge electrodes
Nonequilibrium Thermodynamics Laboratories The Ohio State University
P0=250 torr,N2/He=50/50 mixture,
Ptest=48 torr
RF discharge offne~109 cm-3
RF discharge onne=(1-3)⋅1011 cm-3
M=2 plasma flows with and without RF ionization
Stable, uniform, and diffuse plasmas in both cases
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Shock weakening by the plasma
Shock weakening by the RF plasma: ∆α=150, ∆M=-0.2
1 2 3 4 5 6 7 8 9 10 11 12 1396
100
104
108
112
116
Frame number
Shock angle
Time, sec
RF on
RF off
Slow shock weakening and recovery: thermal effect
Nonequilibrium Thermodynamics Laboratories The Ohio State University
0 100 200 300 400-10.0
-8.0
-6.0
-4.0
J'(J'+1)
ln[Iem/(J'+J"+1)]
230 W DC
T=190 K (J'=1-12)
T=221 K (J'=12-19)
Almost no core flow heating by the dischargeNoticeable boundary layer heating
2140 2160 2180 2200 2220
Wavenumbers
Intensity
DC discharge on (230 W)
RF discharge on (200 W)
Flow temperature measurements(CO FT infrared emission spectroscopy – with 4% CO added)
0 100 200 300 400-10.0
-8.0
-6.0
-4.0
J'(J'+1)
ln[Iem/(J'+J"+1)]
230 W DC, 200 W RF
T=200 K (J'=1-12)
T=271 K (J'=12-19)
with RF
no RF
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Temperature measurements summary
0 40 80 120 160 200180
200
220
240
260
280
300
RF power, W
Rotational temperature, K
Low J' fit (J'=1-12)
High J' fit (J'=12-19)
Fit to all data (J'=1-19)
∆T=15 K (low J′ fit)
∆T=50 K (high J′ fit)
∆T=35 K
(all available data fit)
Temperature rise consistent with shock angle change (∆M=-0.2 for both)Thermal effect
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Flow
DC electrode block
Pulsed electrode block
Optical access window
Static pressure port
Optical access window
Static pressure port
MTV pump laser beam
B
Magnet pole
Flow
east
west
down
up
Sustainer current
Decelerating force Accelerating force
Case 2: Supersonic Flow Control by Low-Temperature MHD
• Pulsed electric field perpendicular to the flow, parallel to magnetic field
• DC sustainer field perpendicular both to flow and pulsed electric field
• Optical access along vertical and horizontal line-of-sight
• Four combinations of current and magnetic field directions: Accelerating or decelerating Lorentz force, j x B
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Low-temperature MHD test sections (M=3, M=4)
• Contoured nozzle• 12 cm long, 4 cm x 2 cm test section• Equipped with pressure ports and Pitot ports• Ceramic/copper pulsed and DC electrode blocks• Stagnation pressure P0=0.2-1.0 atm• Ionization: repetitively pulsed discharge
Static pressure port
Plenum M=4 nozzle insert M=4 test section Diffuser insert
Flow
Nonequilibrium Thermodynamics Laboratories The Ohio State University
To vacuum
Mirror Magnet coil
Flow
He-Ne laser
Magnet pole
Photodiode
Laser Differential Interferometry (LDI) diagnostics: BL density fluctuation spectra measurements
Flow
Reference beam Probe
beam
Nonequilibrium Thermodynamics Laboratories The Ohio State University
P0=150 torr, 2 mm from the wall
Boundary layer visualization by laser sheet scattering:comparison with a 3-D compressible Navier-Stokes flow code
P0=250 torr, 2 mm from the wall
0
5
1
5
2
0
5
1
5
2
0
5
1
5
2
0
5
1
5
2
Laser
λ/4 plate
Cylindrical lens
Cylindrical lens
ICCD camera
Laser sheet
Mirror
Optical window
Flow
Distance to wall
Test section
Scattering signal
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Time resolution ~0.1 µsec, spatialresolution ~100 µm
Rates of vibration-vibration energyexchange for N2-N2 inferred fromlevel populations
Nonequilibrium Thermodynamics Laboratories The Ohio State University
v=2
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0 2 4 6µs
frac
tiona
l pop
ulat
ion
v=4
0.E+00
1.E-03
2.E-03
3.E-03
4.E-03
5.E-03
6.E-03
7.E-03
0 2 4 6µs
frac
tiona
l pop
ulat
ion
Pulsed Raman pumping: time-resolved vibrational level populations of O2
0 5 10 15 20 25 301E-15
1E-14
1E-13
1E-12
Vibrational Quantum Number
Relaxation Rate Constant, cm3/s
Price et al.
Park & Slanger
Klatt et al.
FHO-FR (analytic)
DIDIAV (semiclassical)
Quantum calculations
Kalogerakis et al.
Rates of vibration-vibrationenergy exchange for O2-O2inferred from level populations
Nonequilibrium Thermodynamics Laboratories The Ohio State University
O atom concentration measurements:Two-Photon Absorption Laser Induced Fluorescence (TALIF)
with Xenon Calibration
Measuring ratio of spectrally integratedO atom TALIF signal to that of xenonwith identical laser beams, signalcollection optics, spectral filtering andPMT gain
Relative signal converted to absolute Oatom number density
Estimated combined uncertainty of absolute O atom density about 40%
Nonequilibrium Thermodynamics Laboratories The Ohio State University
0.0E+0 1.0E-3 2.0E-3 3.0E-3 4.0E-30.0E+0
1.0E-5
2.0E-5
3.0E-5
4.0E-5
5.0E-5
Time, seconds
O atom mole fraction
Air
Air-methane, Φ=1.0
1.0E-7 1.0E-6 1.0E-5 1.0E-4 1.0E-3 1.0E-20.0E+0
1.0E-5
2.0E-5
3.0E-5
4.0E-5
5.0E-5
Time, seconds
O atom mole fractionAir
Air-ethylene, Φ=0.5
O atom number density after a single high-voltage nanosecond discharge pulse: TALIF measurements
Air and methane-air mixture
P=60 torr, Φ=1.0
Air and ethylene-air mixture
P=60 torr, Φ=0.5
Peak O atom density in air: 0.9∙1014 cm-3 / pulse, decay time: 2 msec
Kinetic model correctly predicts O atom densities and decay rates in all three cases
Nonequilibrium Thermodynamics Laboratories The Ohio State University
TALIF O atom number density measurements after a burst of high-voltage pulses
Air, methane-air, and ethylene-air mixtures, P=60 torr, Φ=1.0, pulse burst (up to 100 pulses/msec)
Significant O atom accumulation after 100 pulses in air: 0.2%
Half of input pulse energy goes to oxygen dissociation
0.0 0.2 0.4 0.6 0.8 1.01E+13
1E+14
1E+15
1E+16
Time, msec
O atom concentration, cm-3
P=60 torrair
air/CH4, Φ=0.5
air/C2H4, Φ=0.5
Nonequilibrium Thermodynamics Laboratories The Ohio State University
How are we going to predict effect of these species on the flow?
• Applicable for non-collinear collisions of rotating molecules
• Applicable in a wide range of gas temperatures (T~300-10,000 K)
• Excellent agreement with 3-D computer calculations
• Fully analytic
0 5 10 15 20 25 301E-15
1E-14
1E-13
1E-12
Vibrational Quantum Number
Relaxation Rate Constant, cm3/s
Price et al.
Park & Slanger
Klatt et al.
FHO-FR (analytic)
DIDIAV (semiclassical)
Quantum calculations
Vibrational energy transfer and molecular dissociation rate models
Nonequilibrium Thermodynamics Laboratories The Ohio State University
0 2000 4000 6000 8000 100001E-17
1E-16
1E-15
1E-14
1E-13
1E-12
1E-11
1E-10
1E-9
Temperature, K
V-T Rate constant, cm3/s
(1,0→
0,0)
(40,0→
39,0)
(10,0→
9,0)
Rate models applicable up to very high temperatures
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Model validation: NO IR and UV emission behind strong shocks
NO emission profiles behind the normal shock in air. Po=2.25 torr
IR emission, us=3.85 km/sec
UV emission, us=3.78 km/sec
0 20 40 60 800.0
0.2
0.4
0.6
Laboratory time, µsec
NO(A2Σ), 1010 cm3/sec
Experiment
Revised model
0 20 40 60 800.0
0.3
0.6
0.9
1.2
1.5
Laboratory time, µsec
NO IR emission, mW/cm3.sr
Experiment
Model
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Effect of vibrational relaxation on shock standoff distance: quite noticeable
Nitrogen, M=4, T=300 K, Tv=3000 K, P=10 torr, nose radius 5 mmWith and without 1% of water vapor
Stand-off distances increases from 0.9 to 1.3 mm
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Flow
New Research Program: Effect of Excited Species (N2(v), O2(v), O atoms, and O2(a1Δ)) on M=5 Flow Field
Stagnation enthalpy: 0.3-0.6 MJ/kg
Steady-state flow (~ 10 sec)
LENS: 10-15 MJ/kg
Run time ~ 1 msec
Nonequilibrium Thermodynamics Laboratories The Ohio State University
• Stable, high-pressure, nanosecond pulser – DC sustainer discharge in nozzle plenum (P 0 ~ 1 atm)
• Flows: air, N2/He, O2/He, N2/Ar, and O2/Ar
• Varying DC voltage (E/N): targeted energy loading into O2(a1Δ)(E/N=5-10 Td), N2(v), O2(v) (10-50 Td), and O atoms (100-200 Td, no DC)
• M=5 flow in supersonic test section (P ~ 1 torr)
• Blunt body in test section (D~5 mm), shock stand-off distance ~ 1 mm
• Schlieren and plasma shock visualization; shock stand-off distance measurements with and without excited species present
• First spatially resolved measurements of rotational temperature, O2(a1Δ), N2(v), O2(v), and O atoms behind the M=5 bow shock: IR emission, spontaneous Raman, CARS, TALIF (~100 µm resolution)
Objectives
Nonequilibrium Thermodynamics Laboratories The Ohio State University
• Strong vibrational excitation of N2, O2, and H2 using a pulse-burst laser for Raman pumping (20-30 pulses at 1 pulse/µsec rep rate). Measuring vibrationally induced dissociation at high energy loading (several vibrational quanta per molecule) using TALIF
• Comparison with coupled compressible Navier-Stokes / master equation modeling and rate model validation: state-specific vibrational energy transfer and dissociation rates, rates of NO production, O2(a1Δ) quenching rates
• Developing instrumentation for using at LENS hypersonic flow facility
• Demonstrating scaling potential of DOIL laser power to makeThe Application feasible: tens to hundreds of W in a laboratoryscale setup
• MHD: electrical power generation in reentry flows, opening up“transmission windows” through reentry plasma using B field,power generation in scramjets (stagnation temperature too highfor a turbine)
Nonequilibrium Thermodynamics Laboratories The Ohio State University
Plasma assisted ignition / flameholding in high-speed flows
Fuel injectioncavity filledwith plasma
High voltagepulse electrode
Straight channelor nozzle inserts
Optical accesswindows
Flow
Nonequilibrium Thermodynamics Laboratories The Ohio State University