Molecular Sensors Temperature Sensitive Paint John Sullivan Professor – School of Aeronautics and Astronautics Director - Center for Advanced Manufacturing Purdue University Special Government Employee – NASA West Lafayette, IN 47907-2022 Telephone (765)494-1279 Fax       (765)496-1180 john.p.sullivan.1@purdue.edu

Objective Measure temperature distribution and heat transfer distribution on a hydraulic experiment at Beihang University in the next three weeks.

Temperature Sensitive Paint Emission Luminescent Molecule Excitation Quantitative Heat Flux Lamp LED CCD camera Feature Detection -Transition -Vortices -Separation Mach 10 –Tunnel 9 High-mass planetary probes are affected by transition Laminar flow results in 2-8 times less aeroheating

Photo-physical process: -absorb a photon -transition to excited state -Oxygen quenching (PSP) or thermal quenching (TSP) => Pressure and/or temperature dependent luminescent intensity and luminescent lifetime TSP -Temperature Sensitive Paint PSP - Pressure Sensitive Paint

Temperature Sensitive Paint High temperature causes non-radiative decay “thermal quenching” Obeys Arrhenius relation: For limited temp. range Similar molecules to PSP, but in oxygen impermeable binder

Luminescent Paint (TSP/PSP) Data Processing Iref/I P/Pref calibration Acquisition photodetector long-pass filter Iref/I P/Pref Excitation short-pass filter excitation source surface map low cost easy to apply coated model

Current State of the Art of PSP/TSP Temperature Sensitive Paint –T= -196 C to 200 C M=.01 to 10 –Accuracy 1 Degree Centigrade Resolution <. 01 C –Time Response 1 sec Typical (<1 ms demonstrated) Pressure Sensitive Paint –P=.001 to 2 atm M=.05 to 5 –Accuracy 1.0 mbar Resolution .5 mbar –Time response .5 sec Typical ( 1 microsec demonstrated)

Basic Photophysics

Jablonski Diagram

Data Reduction Methods

Data Reduction Methods Intensity Reference Multi-luminophore Paint Time Based Methods

Intensity Reference Wind Off / Wind On Corrects for non-uniform model motion, nonuniform concentration

Multi-luminophore Paint Luminescent molecules with different pressure and temperature sensitivities, overlapping excitations and different emission wavelengths

Time Based Methods Direct Decay Phase Based

Direct Decay Modulated Light Source Point Systems Pulse, Sine wave, square wave Point Systems Camera Systems with image intensifier Time Intensity

Phase Based Lock-in Amplifier FLIM (Fluorescent Lifetime Imaging Method) tan()= 

Temperature Sensitive Paint TSP Same or similar Luminophore as in PSP Oxygen impermeable binder

Global Surface Temperature Measurements Toolbox Temperature Sensitive Paint Thermographic Phosphors Infrared Camera Temperature Sensitive Liquid Crystals Array of Thermocouples

Temperature Sensitive Paint Surface Temperature Correction for Pressure Sensitive Paint Transition Detection Quantitative Heat Transfer Shear Stress - Heat transfer Analogy

Temperature Sensitive Paint Calibrations

TSP Time Response Laser Pulse Heating c specific heat paint thickness  density of polymer c specific heat paint thickness h convection heat transfer coefficient

Ruthenium based TSP tris(2,2’-bipyridyl)ruthenium - Ru(bpy) Excitation and Emission Spectrum of a Ruthenium Based Paint

EuTTA based TSP Europium III Thenoyltrifluoroacetonate EuTTA Emission Spectrum Excitation Spectrum

EuTTA in Model Airplane Dope

Applications Temperature Sensitive Paint (TSP) Transition Detection Low Speed Cryogenic Wind Tunnel Quantitative Heat Transfer Camera Based – M=10 Scanning System Laser Spot Heating

Transition Detection Low Speed TSP –EuTTA in dope Wing heated with photographic spot lamps to ~20 C above ambient 8 bit Camera

Results Low Speed Transition Raw Image (false color)

Quantitative Heat Transfer

Heat Transfer Data Reduction Method 1 Model make out of Thermally Insulating material Measure Match the temperature to analytic solution for a semi-infinite body (Cook-Felderman) Make Model out of a Conductor with a thin insulator on the surface Method 2

Tunnel #9 M=10 Run time ~1.0 sec 1.5 meter Diameter

TSP - EuTTA in dope Metal model Insulating Layer – mylar film (model airplane monokote) 50 microns thick Raw Image

Mach-6 Quiet Tunnel

HIFiRE-5 Model Quiet Flow, α=0 Re = 2.6*106 /ft

TSP Measurements of Material Temperature Temperature profiles from TSP measurement of grinding stainless steel at spark-out condition Temperature profile of machining acquired with TSP sensor (Rubpy)