Thermographic Phosphors Temperature measurements using Laser Induced Phosphorescence (LIP)

Transcription

1 KCFP Södertälje May 8, 2008 Thermographic Phosphors Temperature measurements using Laser Induced Phosphorescence (LIP) Mattias Richter, Johannes Lindén Division of Combustion Physics, Lund University, Sweden Johannes Lindén, Tolvan Division Tolvansson, of Combustion 2007Physics, Lund University KCFP Södertälje May 8, 2008 Outline Introduction to LIP and thermographic phosphors (TP) Applications Temporal 0D, (2D) Spectral 2D, (0D) Fiber measurements Johannes Lindén, Tolvan Division Tolvansson, of Combustion 2007Physics, Lund University 1

2 KCFP Södertälje May 8, 2008 Introduction to thermographic phosphors Terminology Phosphor solid luminescent material or inorganic powder synthesized for purpose of practical application not clearly defined Reasons for misunderstanding: Phosphor (eng.) different from the name Phosphorus (the element) however, Fosfor (sv.) same word as for fosfor (grundämnet) Emits light (phosphorescence) for some time (μs - ms) after exposure of UV or near-uv light (e.g. laser) hence Laser Induced Phosphorescence Johannes Lindén, Tolvan Division Tolvansson, of Combustion 2007Physics, Lund University KCFP Södertälje May 8, 2008 Introduction to thermographic phosphors Thermographic Phosphor Inorganic powder doped with e.g. rare earth ions The dopant material absorbs light at specific wavelengths and emit radiation at longer wavelengths (phosphorescence) Temperature dependence of phosphorescence Lifetime decrease with T Spectral shape changes with T Johannes Lindén, Tolvan Division Tolvansson, of Combustion 2007Physics, Lund University 2

3 KCFP Södertälje May 8, 2008 Introduction to thermographic phosphors Temperature measurements using laser induced phosphorescence Remote and close to non intrusive measurement technique TP can be applied on surfaces using binder TP can be seeded in liquids (and gas flows) Lifetime or spectral intensity ratios used for thermometry 2D-measurements possible Measurement range from cryogenic to 2000 K depending on TP used Johannes Lindén, Tolvan Division Tolvansson, of Combustion 2007Physics, Lund University KCFP Södertälje May 8, 2008 Measurement technique Phosphorescence Phosphorescence: Molecules of the substance gets from the ground state to a triplet state Vibrational relaxation (non-radiative) to a metastable state Slow decay back to the ground state via photon emission Johannes Lindén, Tolvan Division Tolvansson, of Combustion 2007Physics, Lund University 3

4 Schematic experimental setup for the temporal method Thermographic phosphors Lifetime method point measurements Lifetime of phosphorescence decrease with temperature T 1 T 3 > T 2 > T 1 T 2 T 3 4

5 Thermometry using Lifetime method: Decay time Phosphorescence lifetime decreases with increasing temperature Phosphorescence decay of the Mg 3 FGeO 4 :Mn phosphor at different temperatures. IF 657 nm (10 nm FWHM) Typical lifetime: s ms Theoretical lifetime: I 0 t I e Data acquired via photo multiple tube (PMT) and an oscilloscope Fitting measured data to theoretic model gives lifetime Thermographic phosphors Lifetime method Applied in an HCCI Engine Phosphor: La2O2S:Eu Excitation 355 nm Emission: 538 nm Filter: IF 540 ±5 nm Detection: PMT + LeCroy 3 GHz Oscilloscope 5

6 Thermographic phosphors Lifetime method Applied in an HCCI Engine Temperature sensitivity of La 2 O 2 S:Eu at 538 nm 10-4 Calibration curve La2S20:Eu Measurements performed at different locations Lifetime / s Temperature / deg C Thermographic phosphors Lifetime method Applied in an HCCI Engine Temperature / o C , Time resolved measurement Cycle resolved, 10 Hz, 1200 rpm Timing: -60 CAD ATDC 150 consecutive single shots Standard deviation: 0.73 C Time / s (std = ) 6

7 Temperature response to transient Measurements in the after burner of a Volvo Aero, RM 12 turbofan engine Reinforced fan HP compressor Combustor LP turbine Afterburner HP turbine Radial flameholder Exhaust nozzle 7

8 Volvo Aero, RM 12 turbofan engine Harsh environment for performing optical/laser based diagnostics Acoustic vibration due to high levels of noise (several kw/m 2 ) Absorption Interference from background radiation Investigation of the spectral environment 8

9 Resulting Spectrum Flame emission spectrum recorded at maximum afterburner load. Broadband spectral distribution Emission originating from specific molecular transitions in CH and C 2 Atomic transitions from sodium (Na) and potassium (K) are notable Thermometry using Lifetime method: Decay time Temperature sensitivity of Mg 3 FGeO 4 :Mn at 657 nm Calibration data measured over a temperature range corresponding to the sensitivity of the phosphoric material (RT 700 C). 9

10 Surface temperature measurements Temperatures on the back of a flameholder segment equipped with a gasify device Experimental arrangement 10

11 Experimental arrangement Experimental arrangement Nd:Yag laser =266 nm Segment of flameholder coated with phosphor material Lens + Filter IF 657 nm + PMT + Transimpedance amplifier 11

12 Results 1(3) Signals were sampled using a 1 GHz bandwidth oscilloscope (LeCroy). Temperature data (lifetime decays) was recorded at the repetition rate of the excitation laser (10 Hz). Results 2(3) Power Level Angle (PLA) versus time for AMT cycle XX. Temperature data measured for AMT cycle XX. 12

13 Results 4(3) Temperature data measured for a AMT cycle. a) Heating process when going from engine idling (PLA 18) to maximum load without afterburner (PLA 102). b) Cooling process when going from maximum load with the afterburner (PLA 130) to almost engine idling (PLA 24). Thermographic phosphors Spectral method 2D measurements Change of the spectral properties with temperature T 1 T 3 > T 2 > T 1 T 2 T 3 13

14 Thermographic phosphors Spectral method 2D measurements Change of the spectral properties of YAG:Dy with temperature Phosphorescence spectra with respect to temperature. Excitation with 355 nm. Calibration curve for YAG:Dy. Ratio of 455/493 nm vs temperature. Both BaMg 2 Al 16 O 27 :Eu (BAM) and YAG:Dy were tested for the gas phase engine application BaMg 2 Al 16 O 27 :Eu (BAM) Spectral change makes 2D measurements possible Emission in the blue spectral region Short lifetime and very high intensity enables fast measurements without temporal smearing Lifetime / s Temperature / degc 14

15 2D measurement technique IF 400 ± 20nm IF 456 ± 5nm Stereoscope. 5. Calibration for real 2D measurements Stereoscope ICCD IF 400 nm High Pass Oven Thermo couple IF 456 nm Thermo couple Laser, = 355nm 15

16 2D surface temperature / outlet nozzle EBK munstycke ICCD St ereoskop SL Nd: YAG Laser Laser wavelength: Laser rep. rate: Laser energy: Probed area: Camera: Stereoscope: Exposure time: Filter: 355 nm 10 Hz ~100 mj ca 1 dm2 on nozzle CCD 576*384 px 100 ns 458 nm, 493 nm Division of images to get intensity ratio and thus temperature Sample images from surface measurements using YAG:DY 458 nm 493 nm Resulting temperatur image deg C / = 16

17 KCFP Södertälje May 8, 2008 Fiber measurements Johannes Lindén, Tolvan Division Tolvansson, of Combustion 2007Physics, Lund University KCFP Södertälje May 8, 2008 Fiber measurements Multiple point measurements Non optical engine not restricted to low load conditions Verification of theoretical walland cylinder temperature model Johannes Lindén, Tolvan Division Tolvansson, of Combustion 2007Physics, Lund University 17

18 KCFP Södertälje Temperature / C May 8, Mg FGeO :Mn 4 6 Lifetime Ratio Y 2 O 3 :Eu 10 4 La 2 O 2 S:Eu 624 La 2 O 2 S:Eu 538 YVO :Dy CdWO La 2 O 2 S:Eu 512 ZnO:Zn YAG:Tb 10 2 Lifetime / s 10 6 ZnO:Zn 510 ZnO:Ga 10 1 Ratio BAM YAG:Dy 10 7 LuSiO 5 :Ce Y 2 SiO 5 :Ce Y O S:Sm 2 2 YAlO BAM 10 8 ZnS:Ag YAlO 3 1 (Sr,Mg) SiO :Eu Gustaf Särner 2008 Johannes Lindén, Tolvan Division Tolvansson, of Combustion Physics, 200Lund University Temperature / K 10 2 KCFP Södertälje May 8, 2008 Thank you for your attention! Johannes Lindén, Tolvan Division Tolvansson, of Combustion 2007Physics, Lund University 18