Chapter 6: Surface Thermometry – Thermographic Phosphors TU Darmstadt, Germany Dept. of Mechanical Engineering Institute for Reactive Flows and Diagnostics
A. Dreizler
Andreas Dreizler | 1 Outline phosphor thermometry
• Introduction & Motivation • “Decay-Time Method” versus “Ratio Method”: comparing precision and accuracy • Error treatment for decay-time method • Application examples
Andreas Dreizler | 2 Surface temperature: diagnostics
Thermocouples - Invasive, limited spatial and temporal resolution, only point measurements Pyrometry (Infrared thermometry) - Emission coefficient generally unknown - Sensitive against chemiluminescence and stray light Temperature sensitive paints (TSP - coated), thermoliquid crystals (TLC) - Temperature range < 380 K Heat sensitive paints (HSP - coated) - No temporal resolution
Thermographic phosphors (TGP – coated) + Broad temperature sensitive range (7 K -1870 K) + Insensitive against blackbody radiation, stray light and chemiluminescence + High spatial and temporal resolution, 2D diagnostics
Andreas Dreizler | 3 Thermographic Phosphors
Thermographic phosphors: • Rare-earth or transition metal doped ceramic materials • Exploit temperature dependent spectroscopic properties following electronic excitation
Andreas Dreizler | 4 Introduction & Motivation I
Principle of Phosphor Thermometry: • Coat surface with thermographic phosphor • Excite coating with UV-light source • Detect emission with appropriate device either • time-resolved (fixed spectral range) or • Time-integrated and spectrally resolved (fixed temporal range)
Andreas Dreizler | 5 Introduction & Motivation II
Approaches of Phosphor Thermometry
R Intensity WavelengthTime
Andreas Dreizler | 6 Fuhrmann et int. Dreizler. Proc. Combust. Inst. (2013) 34:3611 – 3618 Introduction & Motivation III
• Comparison of the two most popular approaches: • Luminescence Lifetime (Decay-time) • Intensity Ratio (Two-line) • Motivation: • Decision support required for users • Comparison to highlight pros vs cons • Investigation of sensitivities, precision, accuracy and application • Procedure • Use two CMOS high-speed cameras (same data-set) • Exemplified for phosphor which exhibits sensitivities in both
approaches: Mg4FGeO6: Mn Andreas Dreizler | 7 Experimental Setup
1 cm²
Andreas Dreizler | 8 Data evaluation
• Nonlinearity intensity-correction of the CMOS Chip • Image matching by pinhole model (Software: Davis 7) Lifetime Intensity ratio - Pixelwise fitting of waveforms - Pixelwise temporal integration: - Brübach Algorithm + Linear Regression of the Sum (LRS)
- Two ratios R1 and R2 used: - R1: LRS
(corresponds to 1 image @50kHz) - R2:
Brübach, J. et al., Opt. Laser Eng., 47 (1), 2009 Everest, M. A. et al., Rev. Sci. Instrum., 79, 2008 (corresponds to 50 images @50kHz) Andreas Dreizler | 9 Fuhrmann et int. Dreizler. Appl. Phys. B (2014) 116:359 – 369 Results: Temperature dependent characteristics
• Temperature-Lifetime / Temperature-Ratio characteristics
-2 10 0.26 • Temperature-Lifetime characteristics of both spectral bands similar
-3 10 0.2 • Temperature-Ratio characteristics for both ratios similar as
Ratio ( - ) Ratio well
Lifetime ( s ) Lifetime -4 10 0.14 Lifetime ( 660 nm ) • Very different Lifetime ( 633 nm ) Ratio 1 sensitivities for lifetime approach and -5 Ratio 2 10 0.08 300 400 500 600 700 800 900 only slightly differing Temperature ( K ) sensitivities for ratio approach Andreas Dreizler | 10 Results: Precision I
• Shot-to-Shot (temporal) standard deviations
Lifetime ( 660 nm ) • Comparable precision -1 Lifetime ( 633 nm ) of both techniques at 10 Ratio 1 lower temperatures Ratio 2 • Lifetime method ~2
-2 orders of magnitude 10 better at higher temperatures
-3 10
Normalized temporal standard deviation ( - ) deviation standard temporal Normalized 300 400 500 600 700 800 900 Temperature ( K )
Andreas Dreizler | 11 Results: Precision II
• Pixel-to-pixel (spatial) standard deviations
• Huge difference in
-1 spatial precision 10 between the two techniques
-2 • Spatial precision of 10 lifetime method superior over the entire temperature Lifetime ( 660 nm ) -3 range 10 Lifetime ( 633 nm ) Ratio 1 Ratio 2
Normalized spatial standard deviation ( - ) deviation standard spatial Normalized 300 400 500 600 700 800 900 Temperature ( K )
Andreas Dreizler | 12 Results: Accuracy I
• Evaluation of systematic errors
-2 T = 515 K T = 780 K 10 0.26 • Evaluated at two different temperatures corresponding to two
-3 different sensitivities 10 0.2 in the temperature lifetime characteristic
Ratio ( - ) Ratio • Calibration at fixed
Lifetime ( s ) Lifetime -4 10 0.14 conditions and then Lifetime ( 660 nm ) parametric variation: Lifetime ( 633 nm ) Ratio 1 • Energy variation • Changing -5 Ratio 2 10 0.08 300 400 500 600 700 800 900 settings in optical Temperature ( K ) setup
Andreas Dreizler | 13 Results: Accuracy II
• Dependency on excitation energy at T = 515K
T = 515 K 600 Lifetime 660nm • Inaccuracy for too low Ratio 1 excitations energies 550 Ratio 2 of lifetime approach True value well known (i.e. Brübach et al. 2008) 500
Temperature ( K ) Temperature • Ratio 2 rather robust 450 against energy 0 10 variations, but inaccuracy over whole -2 10 energy range
-4 10 0 1 10 10
Normalized temporal Normalized standard deviation ( - ) deviation standard Excitation energy ( mJ )
Andreas Dreizler | 14 Results: Accuracy III
• Dependency on excitation energy at T = 780K
T = 780 K 1000 Lifetime 660nm • Lifetime approach Ratio 1 very accurate due to 900 Ratio 2 high sensitivity True value • Ratio 1 & 2 show 800 overestimation of Temperature ( K ) Temperature more than 100 K at 700 lower energies 0 10
-2 10
-4 10 0 1 10 10
Normalized temporal Normalized standard deviation ( - ) deviation standard Excitation energy ( mJ )
Andreas Dreizler | 15 Results: Accuracy IV
• Accuracy due to changes of settings in the optical setup
T = 515 K T = 780 K 55 30 LifetimeLifetime ( 660 ( nm660 ) nm ) Lifetime ( 660 nm ) RatioRatio 1 1 Ratio 1 00 25 RatioRatio 2 2 Ratio 2 -5 20 -5 Index -10 1 – Filter rotation 15 -10 2 – Increase distance -15 (1cm) 10 -15 3 – Increase distance -20 (2cm) 5 4 – Increase distance
-20 (4cm) Temperature difference ( K ) difference Temperature Temperature difference ( K ) difference Temperature -25 0 5 – Change camera
Temperature difference ( K ) difference Temperature -25 angle -30 -5 1 2 3 4 5 1 2 3 4 5 Index Index -30 Andreas Dreizler1 | 16 2 3 4 5 Index Results: Cooling device I
• Stainless steel block with cooling channel placed inside oven • When block is at designated temperature, cold water is pumped through cooling channel • For image mapping purposes target dots have been transferred to device
Tube furnace Cooling channel
Stainless steel block Target dots
Phosphor coating
Kissel, T., PhD Thesis, TU Darmstadt, 2011
Andreas Dreizler | 17 Results: Cooling device II
• Transient Experiment • Same set of data for all three methods
Andreas Dreizler | 18
8
4
y ( mm ) Lifetime (660nm) Temperature in K 0 Results300 400 : 500Cooling0 4 device8 12 III Temperature in K x ( mm ) 300 400 500
8 Temperature in KTemperature in K • 300Stationary400 500 T-distribution 5over last 16 frames Lifetime ( 660 nm ) 300 400 500 Lifetime ( 660 nm ) 8 Ratio 1 •4 Statistics for these temperature maps: Ratio 1 y ( mm ) 0 Ratio 2 8 Lifetime (660nm) Ratio 2 4 Temperature in K 0 y ( mm ) 0 4 8 12 Lifetimex ( mm (660nm) ) 300 400-5 500 4 0 y ( mm ) 0 4 8 12 8 Lifetimex ( mm 8(660nm) ) -10 500 0 0 4 8 12 8 4 x ( mm ) 450 y ( mm ) -15 8 Ratio 1 4 Vertical 0 y ( mm ) 400 0 4 8 12 binning Ratiox 1( mm4 ) 4 -20 0
y ( mm ) 0 4 y ( mm ) 8 12 350
8 Ratiox (1 mm ) Temperature difference ( K ) difference Temperature
0 -25 temperatureK) (
0 4 8 12 Lifetime (660nm) Verticallyaveraged 8 300 4 x ( mm )
y ( mm ) 0 -30 8 Ratio 2 4 0 4 8 121 2 3 4 5 0 4 8 12 0 y ( mm ) 0 4 8 12 Index x ( mm ) Ratiox 2( mm ) x ( mm ) 4 -3 0Andreas Dreizler | 19 y ( mm ) 0 4 8 12 x 10 Ratiox (2 mm ) 12 0 0 4 8 12 x ( mm ) 10
8
4 6 y ( mm )
Ratio 1 4
Normalizedtemporal standarddeviation ) - ( 0 2 0 4 8 12 300 400 500 x ( mm ) Vertically averaged temperature ( K )
0.08 8 0.06
0.04 4
y ( mm ) 0.02
Ratio 2 Normalizedspatial standarddeviation ) - ( 0 0 0 4 8 12 300 400 500 x ( mm ) Vertically averaged temperature ( K ) Temperature in K Lifetime ( 660 nm ) 300 400 500 Ratio 1 Ratio 2
8 500 8 450 4
y ( mm ) Lifetime (660nm) 400 Temperature4 in K 0 Results300 400 : 500Cooling0 4 device8 12 III
Temperaturey ( mm ) in K x ( mm ) 350 300 400 500
temperatureK) ( 8 Temperature in LifetimeK (660nm) Verticallyaveraged 300 • 300Stationary400 500 T-distribution 5over last 16 frames Lifetime ( 660 nm ) 8 0 •4 Statistics0 for these4 temperature8 12 maps: 0 4 Ratio 18 12 y ( mm ) 0 8 Lifetime (660nm) Ratiox ( mm 2 ) 4 xTemperature ( mm ) in K 0 -3 y ( mm ) 0 4 8 12 x 10 Lifetimex ( mm (660nm) ) 300 400-5 500 4 12 0 y ( mm ) 0 4 8 12 8 Lifetime8 (660nm) x ( mm ) -10 0 10 0 4 8 12 8 4 x ( mm )
y ( mm ) -15 8 8 Ratio 1 4 Vertical 0 y ( mm ) 0 4 48 12 binning Ratiox 1( mm ) 6 4 -20 0 y ( mm ) y ( mm ) 0 4 8 12 8 Ratiox (1 mm )
Temperature difference ( K ) difference Temperature 4 0 Ratio 1 -25 0 4 8 12 Normalizedtemporal 8 standarddeviation ) - ( 4 x ( mm0 ) 2 y ( mm ) -30 300 400 500 8 Ratio 2 0 4 8 12 4 1 2 3 4 5 0 Vertically averaged temperature ( K ) y ( mm ) 0 4 8 12 x ( mm ) Index Ratio 2 4 x ( mm ) 0Andreas Dreizler | 20 y ( mm ) 0 4 8 12 0.08 Ratiox (2 mm ) 0 0 4 88 12 x ( mm ) 0.06
0.04 4
y ( mm ) 0.02
Ratio 2 Normalizedspatial standarddeviation ) - ( 0 0 0 4 8 12 300 400 500 x ( mm ) Vertically averaged temperature ( K ) Temperature in K Lifetime ( 660 nm ) 300 400 500 Ratio 1 Ratio 2
8 500 450
400 4
y ( mm ) 350 temperatureK) ( Lifetime (660nm) Verticallyaveraged 300 0 0 4 8 12 0 4 8 12 x ( mm ) x ( mm ) -3 x 10 12 8 8 10
4 8
y ( mm ) Lifetime (660nm) Temperature in K 0 Results300 4400 : 500Cooling0 4 device8 12 III 6
Temperaturey ( mm ) in K x ( mm ) 300 400 500 4 8 Temperature inRatio K 1 Normalizedtemporal • 300Stationary400 500 T-distribution 5over last 16 framesstandarddeviation ) - ( Lifetime ( 660 nm ) 8 0 2 •4 Statistics0 for 4these temperature8 12 maps: 300 Ratio400 1 500 y ( mm ) 0 8 Lifetime (660nm) Vertically averagedRatio 2temperature ( K ) 4 xTemperature ( mm ) in K 0 y ( mm ) 0 4 8 12 Lifetimex ( mm (660nm) ) 300 400-5 500 4 0.08 0 y ( mm ) 0 4 8 12 8 Lifetimex (8 mm (660nm) ) -10 0 0 4 8 12 8 0.06 4 x ( mm )
y ( mm ) -15 8 Ratio 1 4 Vertical 0 0.04 y ( mm ) 0 4 48 12 binning Ratiox 1( mm ) 4 -20
0 y ( mm ) y ( mm ) 0 4 8 12
8 Ratiox (1 mm ) 0.02 Temperature difference ( K ) difference Temperature
0 -25 Normalizedspatial 0 4 8 12Ratio 2
8 standarddeviation ) - ( 4 x ( mm )
y ( mm ) 0 0 -30 8 Ratio 2 300 400 500 4 0 4 8 121 2 3 4 5 0 y ( mm ) 0 4 8 12 x ( mm ) Index Vertically averaged temperature ( K ) Ratio 2 4 x ( mm ) 0Andreas Dreizler | 21 y ( mm ) 0 4 8 12 Ratiox (2 mm ) 0 0 4 8 12 x ( mm ) Summary & Conclusions
Comparison of Mg4FGeO6: Mn for the lifetime and the intensity ratio method in terms of • Precision • Accuracy • Application (cooling device)
Main results • High temperature range (>650K): Lifetime method is superior in all aspects • Low temperature range: Lifetime method superior for spatial standard deviation and for accuracy, similar temporal standard deviations • Only valid for the phosphor under consideration • For other phosphors similar investigations required Fuhrmann et al. PCI 34, 2013
Andreas Dreizler | 22 Error treatment for the decay-time method
1. Introduction
2. Measurement chain / Error sources
3. Applications
4. Summary
For details see: Brübach, Pflitsch, Dreizler, Atakan. Prog. Energy Combust. Sci. 39, 37 – 60 (2013)
Andreas Dreizler / TU Darmstadt 25 1. Introduction
2. Measurement chain / Error sources
3. Applications
4. Summary
Andreas Dreizler / TU Darmstadt 26 Combustion applications: mostly used approaches
• Most often used approaches are decay-time and two-spectral-band- method • As discussed: Decay-time method does have the potential for superior precision and accuracy (especially in 2D application); see Fuhrmann, Brübach and Dreizler, PCI 33, 2013 • Decay-time varies with temperature due to varying energy transfer processes
Andreas Dreizler / TU Darmstadt 27 Thermographic Phosphors: materials showing temperature dependent decay times
Approx. 100 different phosphors documented in literature See Brübach et al. PECS 2013
Magnesium-Fluorogermanate doped with manganese:
Mg4FGeO6:Mn
Allison and Gillies, Rev. Sci. Instr., 68:2615-2650, 1997.
Andreas Dreizler / TU Darmstadt 28 Spectra
Mg4FGeO6:Mn
Excitation Emission Possible by standard laser wavelength may interfere with luminous combustion
Andreas Dreizler / TU Darmstadt 29 Experimental Setup – 0D
Andreas Dreizler / TU Darmstadt 30 Experimental Setup – 2D
CMOS Kamera LaVision HSS6: • Dynamic Range: 12 bit • max. frame rate of 675 kHz at a resolution of 64 x 16 Pixels
Andreas Dreizler / TU Darmstadt 31 Calibration in well-controlled environments (oven)
. Phosphor: Mg4FGeO6:Mn . Substrate: Stainless Steel (1.4301) Low sens. . Gas phase pressure: 1 bar (air) . Detection: PMT at 500 Ω High sens.
Cut-off due to terminator
Andreas Dreizler / TU Darmstadt 32 1. Introduction
2. Measurement chain / Error sources
3. Applications
4. Summary
Andreas Dreizler / TU Darmstadt 33 Measurement chain
Actual Calibration Measurement
Brübach, J.; ISA 55th Int. Instrumentation Symposium, 2009 Andreas Dreizler / TU Darmstadt 34 Measurement chain
Actual Calibration Measurement
Brübach, J.; ISA 55th Int. Instrumentation Symposium, 2009 Andreas Dreizler / TU Darmstadt 35 Error class 1: Thermal interactions
Andreas Dreizler / TU Darmstadt 36 Error class 1: Thermal interactions
. Device under test (DUT) and phosphor or phosphor and calibration thermometer are not in thermal equilibrium
. Impact of the presence of the phosphor on the thermal state of the DUT (e.g. heat insulation) → “semi-invasive” method
. Excitation induced heating of the phosphor → check by power scan
Andreas Dreizler / TU Darmstadt 37 Error class 2: Photophysical properties of the phosphor
Andreas Dreizler / TU Darmstadt 38 Error class 2: Photophysical properties of the phosphor
. Impact of the transfer function of the phosphor Temperature sensitivity, varies with temperature Temporal low pass character due to finite decay time (thermal inertia versus decy time)
. Parameters that manipulate the transfer function of the phosphor Diffusion processes between the phosphor material and the substrate due to heat treatments Chemical and physical environment (oxygen quenching) Laser excitation (variations with intensity)
Andreas Dreizler / TU Darmstadt 39 Error class 2:
Excitation irradiance
signal intensitysignal Normalised Fixed temperature Identical TGP-coating
Time ( ms )
. Decay behaviour “more multi-exponential” at higher laser intensities . Significant influence of the position of the fitting window
Brübach, J.; Feist, J. P.; Dreizler, A.: Meas. Sci. Technol., 19(2):025602, 2008.
Andreas Dreizler / TU Darmstadt 40 Error class 2: Decay time @ 294 K after heat treatment
Stainless steel Powder
Mg4FGeO6:Mn coating on a stainless steel substrate Pure powder Mg4FGeO6:Mn T = 294 K T = 294 K
Dependency on: . Substrate material . Duration of the heat treatment . Heat treatment temperature Diffusion process between phosphor und substrate
Brübach, J.; Feist, J. P.; Dreizler, A.: Meas. Sci. Technol., 19(2):025602, 2008.
Andreas Dreizler / TU Darmstadt 41 Error class 2: Surrounding gas phase
Mg4FGeO6:Mn No significant dependency on the composition and pressure of the gas phase
Brübach, J.; Dreizler, A.; Janicka, J.: Meas. Sci. Technol., 18(3):764–770, 2007.
Andreas Dreizler / TU Darmstadt 42 Error class 2: Surrounding gas phase
O2 concentration
Y2O3:Eu Dependency on the oxygen concentration
Brübach, J.; Dreizler, A.; Janicka, J.: Meas. Sci. Technol., 18(3):764–770, 2007.
Andreas Dreizler / TU Darmstadt 43 Error class 3: Signal detection
Andreas Dreizler / TU Darmstadt 44 Error class 3: Signal detection – overview
. Impact of the transfer function of the detection system limited spatial, temporal and spectral resolution nonlinear behaviour of the detector (CMOS camera)
. Parameters that manipulate the transfer function of the detection system small changes in the alignment (intensity ratio, see PCI 33-paper 2013) terminating resistor, BNC length, amplifier (PMT, decay time)
. Optical and electrical interferences optical interf. (e.g. background radiation, CL, fluorescence of substrate,…) most often temporally not correlated (worse precision) electrical interf. (e.g. high voltage Q-switch electronics) might be temporally correlated (worse accuracy)
. Dynamic DUTs (e.g. moving surfaces) signal decay might be superimposed by spatial variations of the absolute luminescence intensity; depending on the homogeneity of the excitation irradiance and the phosphor coating as well as on spatial temperature variation
Andreas Dreizler / TU Darmstadt 45 Error class 3: Signal detection – PMT versus CMOS
. Photomultiplier unproblematic . CMOS camera shows problems regarding Linearity Pixel-to-pixel homogeneity Offset stability
Kissel, T.; Baum, E.; Dreizler, A.; Brübach, J.: Appl. Phys. B, 96:731–734, 2009.
Andreas Dreizler / TU Darmstadt 46 Error class 3: Non-linear detector behaviour
Correction function for each pixel fixes the problem Temporal std. dev.
Spatial std. dev.
Kissel, T.; Baum, E.; Dreizler, A.; Brübach, J.: Appl. Phys. B, 96:731–734, 2009.
Andreas Dreizler / TU Darmstadt 47 Error class 3: Coating thickness and CMOS frame rate
Variation of coating thickness Variation of frame rate: and luminescence intensity 304 Increasing Thickness 302 ~70 values
300
400 600 800 1000 1200 1400 1600 1800 2000 2200 298 counts 296
Resulting Temperature: 294
TemperatureK) ( 299,4 K 298,0 K 297,4 K 292 ±3,0 K ±3,3 K ±5,7 K 290 ~7 values probing the decay 288 1 2 3 10 10 10 Framerate ( kHz ) 280 285 290 295 300 305 310 315 Temperature ( K ) Minimum of standard deviation at No significant influence! high temporal discretisation.
Andreas Dreizler / TU Darmstadt 48 Error Class 3: Parameters impacting the transfer function
Modified low pass character of the detection system (PMT) due to terminating resisitor might strongly change the calibration curve, especially at low decay times
Andreas Dreizler / TU Darmstadt 49 Error class 4: Algorithm for the data reduction
Andreas Dreizler / TU Darmstadt 50 Error class 4: Algorithm for the data reduction
Problem: Decay characteristics are not single-exp. Predefined
fitting window: Decay time ( ms ) ms( time Decay
Temperature ( K )
Iterative Normalized intensityNormalized
fitting window: Decay time ( ms ) ms( time Decay
Time ( ms ) Temperature ( K ) Brübach, J.; Janicka, J.; Dreizler, A.: Opt. Laser Eng., 47(1):75–79, 2009.
Andreas Dreizler / TU Darmstadt 51 Error class 5: Comparison of the scalar values
Andreas Dreizler / TU Darmstadt 52 Error class 5: Comparison of the scalar values
. Error depending on the calibration temperature intervals and the quality of the interpolation in between the calibration points. . High error potential in strongly curved regimes of the calibration curve
. Calibration intervals of at least ΔT = 20K or even ΔT = 10K are recommended.
Andreas Dreizler / TU Darmstadt 53 Error class 6: Uncertainty of the calibration thermometer
Andreas Dreizler / TU Darmstadt 54 Error class 6: Uncertainty of the calibration thermometer
. Most often, thermocouples are employed
. High quality thermocouples offer an accuracy of better than 0.4 % of the absolute temperature.
Andreas Dreizler / TU Darmstadt 55 Error Review Provided a careful practice: Systematic Error: → Systematic Error < 1 %
Error class max. error 1. Heat transfer ? 2. Photophysics Excitation O (101 K) Dopant concentration O (102 K) Heat treatments O (101 K) Surrounding gas phase O (102 K)
3. Detection system O (102 K) 4. Algorithm for data reduction O (101 K) 5. Comparison of calibration and measurement O (101 K) 6. Accuracy of the calibration thermocouple O (100 K)
Statistical Error:
Shot-to-shot standard devitation: approx. 2 K Brübach, J.; ISA 55th Int. Instrumentation Symposium, 2009 Andreas Dreizler / TU Darmstadt 56 1. Introduction
2. Measurement chain / Error sources
3. Applications
4. Summary
Andreas Dreizler / TU Darmstadt 57 RSM Combustor
Combustor operation Limits
T3 300 K – 680 K
P3 0.2 MPa – 1.0 MPa
m3 25 g/s – 150 g/s
φLeanPremixed >0.65 for S=0.7-1.3
φLeanPremixed+Pilot >0.60 for S=0.7-1.3 S 0.0 -1.6
Herrmann et int. Dreizler. Flow Turb. Combust. (2019) https://doi.org/10.1007/s10494-018-9999-y
Andreas Dreizler / TU Darmstadt 58 RSM Combustor
. Standard operation point
Operation conditions
T3 623K
P3 0.25 MPa
m 3 0.030kg/s
FLeanPremixed 0.65/0% Pilot
FLeanPremixed+Pilot 0.65/10% Pilot S 0.7
m 5 0.0125 kg/s
T5 623 K
Low-pass (490nm ) filtered Chemiluminescence images from piloted and premixed flames
Andreas Dreizler / TU Darmstadt 59 Selected results: wall thermometry
. 2d wall temperature fields
Magnified view of the coated liner. Coating thickness t 10um Coated area Uncoated• Temperature area measurement in flameFlow -wallDirection contact zone at 20mm < x < 45mm • Influence of cooling film visible in wakes behind single holes Greifenstein et int. Dreizler. Experiments in Fluids (2019) 60 (1):10 Andreas Dreizler / TU Darmstadt 60 Optically accessible combustion engine CMOS Fuhrmann, N. ; Kissel, T. ; Dreizler, A. ; Brübach, J. : Meas. Sci. Technol., Meas. Sci. Technol.22 045301 (2011) Brübach, J. ; Kissel, T. ; Frotscher, M. ; Euler, M. ; Albert, M. ; Dreizler, A. : J. Lumin., 131, 559 – 564 (2011) Andreas Dreizler / TU Darmstadt 61 Optically accessible combustion engine See Appl. Phys. B 2011, Fuhramnn et al. Temperatur at exhaust valve: • DI-ICE @ 2000 min-1 • Coating: Gd3Ga5O12:Cr + Ulfalux Ofenlack • Spatial resolution: 188 µm/Pixel @ 64x64 Pixel (360 kHz framerate) FOV Exhaust gas valves coating Intake valves Andreas Dreizler / TU Darmstadt 62 Optically accessible combustion engine Fired engine operation: • Temperature measurement at selected CAD Intake Compr. Expa. exhaust N. Fuhrmann, M. Schild, D. Bensing, S.A. Kaiser, C. Schulz, J. Brübach, A. Dreizler: Two-dimensional cycle-resolved exhaust valve temperature measurements in an optically accessible internal combustion engine using thermographic phosphors; Applied Physics B, DOI 10.1007/s00340-011-4819-2. Andreas Dreizler / TU Darmstadt 63 Extension to high speed phosphor thermometry in ICE • Former measurements use 10Hz laser-systems for phosphor thermometry • Temperatures originate from different cycles → averaging of uncorrelated single shots [2] High speed phosphor thermometry Use laser at high repetition rate to resolve temperatures within cycles Andreas Dreizler / TU Darmstadt 64 Resolving singly cycles by high speed TGP . High speed phosphor thermometry • Very fast decaying phosphors • Well below 167µs (1°CA at 1000 rpm) Steep increase due to detection system Can be optimized -4 10 6 4+ Mg2TiO4:Mn 5 -5 10 4 ( s ) s) ( 3 -6 10 2 Lifetime 1 -7 10 0 300 320 340 360 380 400 420 440 Temporalstandard deviation K) ( 300 320 340 360 380 400 420 440 Temperature ( K ) Temperature ( K ) [3] Andreas Dreizler / TU Darmstadt 65 Influence of laser-induced heating . Challenges when using High Speed Phosphor Thermometry: . → Laser-induced heating effects 340 • Due to high power delivered by 335 laser 330 • Quantify by energy-scan 325 • Trade-off between precision TemperatureK) ( 320 and accuracy 315 -3 -2 -1 10 10 10 [3] Optimum at E = 13µJ : Energy ( mJ ) Standard deviation below 1K Systematic error of 2.5K Andreas Dreizler / TU Darmstadt 66 Set-up and realization . Experimental Setup Coating Spark plug dummy • Coated via airbrush Inlet valves Outlet valves • Dispersion of binder and phosphor Quartz glass Photomultiplier- Engine ring and tube piston disc • Motored at 1000rpm • No injection and Broadband ignition mirror High-speed UV-laser, • Compression ratio 266nm, 6kHz 8.5:1 Andreas Dreizler / TU Darmstadt 67 Results for motored engine (no combustion) . Temperature progression of the spark plug dummy 344 Intake Compr. Expansion Exhaust Mean values and 342 • temporal standard 340 deviations of 100 338 cylces 336 TemperatureK) ( • Resolution of 1 ° CA 334 • Precision of about 1-2 K 332 -360 -270 -180 -90 0 90 180 270 360 Crank angle ( ° ) [3] Andreas Dreizler / TU Darmstadt 68 Wall temperature measurements during flame wall interactions in IC engine flame position OH-PLIF (3 pulse burst) LOH-LIF LTGP Temperature 2D-phosphor thermometry at piston surface (crank-angle resolved) Ding et int. Dreizler, Böhm. Appl. Phys. B (2017) 123:110 Dreizler | 69 Phosphor thermometry . Decay-time method . Ex-situ calibration . Engine requirements . Fast temperature measurements (~ 10µs) . High sensitivity, high SNR (~ 5K) . Suitable thermographic phosphor: Gd3Ga5O12:Cr,Cer Dreizler | 70 Experimental setup for studying flame-induced heating Dreizler | 71 Engine operational conditions Heating up the engine for several runs multiple runs recorded 300 cycles 100 motored fired 100 cycles, every second is recorded HS-TPT 15 Images from -6.5 to 14.5 CAD aTDC OH-PLIF 3 Images at -2, -0.5 and 1.0 CAD aTDC Dreizler | 72 Engine operational conditions Operating Point fuel CH4 pin 950 mbar Tin 32°C Speed 800 rpm Imep 5.3 bar lambda 1.0 and 1.3 tignition -11 and -16 CAD aTDC Dreizler | 73 Flame position and wall temperature . coherence of flame impingement and wall temperature increase . reproducible temperature evolution Dreizler | 74 Temperature rise during flame-wall interaction Phase averaged Conditional averaged . Maximum heating rates of up to 20,000 K/s Dreizler | 75 1. Introduction 2. Measurement chain / Error sources 3. Applications 4. Summary Andreas Dreizler / TU Darmstadt 76 Summary . Systems for 0D und 2D phosphor thermometry . Decay-time method superior compared to ratio method with respect to precision and accuracy . Quantification of systematic and statistic error . Application (relatively) straight forward, even to complex systems . High potential for further applications Andreas Dreizler / TU Darmstadt 77