Temperature Sensitive Paint Research Articles

1502 重ね塗り感圧・感温塗料を用いた低速流れ場における圧力・温度計測技術(OS15-1 先端的熱流体計測法,オーガナイズドセッション)

Recently, measurement method using pressure sensitive paint (PSP) and temperature sensitive paint (TSP) is attractive in measurement of pressure and temperature field on surfaces. However, PSP has temperature dependence as well as pressure sensitivity. Temperature dependence will be the factor which brings an error in pressure measurement using PSP, so temperature correction is needed to obtain the highly precise pressure distribution. So, in this research we apply use the combined method using both PSP and TSP by stacking PSP and TSP layer up. Using the combined method, the temperature distribution obtained by TSP can be used for the temperature compensation of PSP. We call this combined method as "Dual-layer PSP/TSP". In this research, we clarified that the sensitivity of the dual-layer PSP/TSP in low-speed flow fields against pressure and temperature is comparable to that of mono-layer PSP or TSP, showing the feasibility of the dual-layer PSP/TSP for the measurement in low-speed flow fields.

Analytical Method for Determining Heat Flux from Temperature-Sensitive-Paint Measurements in Hypersonic Tunnels

This paper describes the analytical method used for temperature-sensitive-paint measurements to obtain quantitative global heat flux diagnostics in hypersonic tunnels. An exact inverse solution of the one-dimensional unsteady heat conduction equation for a polymer layer (temperature-sensitive paint or temperature-sensitive paint and an insulator layer) on a base of any material is obtained to calculate heat flux into the polymer surface as an explicit function of a time-dependent surface temperature change measured by temperature-sensitive paint. In addition, an analytical solution of the three-dimensional unsteady heat conduction equation is given to consider the effect of the lateral heat conduction. Simulations and experiments are conducted to examine the analytical method and assess the relevant factors regarding the measurement uncertainty.

Luminescent terbium and europium probes for lifetime based sensing of temperature between 0 and 70 °C

Organic europium (III) and terbium (III) complexes (refered to as Eu1, Eu2, and Tb-L1, Tb-L2, respectively) have been synthesized that display bright emission and small bandwidth. Tb-L1 and Tb-L2 show lifetimes in the order of almost 1 ms at room temperature, good color purity, and high relative photoluminescence quantum yields. This makes them excellent probes for sensing temperature via measurement of luminescence lifetime. Probes Eu1, Eu2, Tb-L1 and Tb-L2 were incorporated into various polymer matrices to give sensor films for use as temperature-sensitive paints (TSPs). Eu (III) complexes have the advantage of being effectively excited by purple light-emitting diodes with their peak wavelengths of 405 nm. All TSPs based on these europium and terbium probes display good sensitivities to temperature, in particular, TSP based on Tb-L1 and Tb-L2 can show temperature-lifetime sensitivities of −13.8 μs per °C and − 9.2 μs per °C, respectively. Assuming a precision of ± 1 μs in the determination of lifetime, this will enable temperature to be determined with a precision of around ± 0.1 °C. This temperature dependence is the highest one reported so far for lanthanide complexes.

Effects of Soil Temperature during Fire on Seed Survival in Florida Sand Pine Scrub

Soil temperatures recorded with thermocouples and temperature-sensitive paints were quantified during Florida sand pine scrub prescribed fires at Ocala National Forest and Archbold Biological Station in May 1993. Thermocouples and glass petri dishes painted with temperature-sensitive paints and containing seeds ofEriogonum floridanumwere placed at 0 cm and 2 cm depth, and in vegetated and open microsites. Maximum temperatures were higher and peak temperature durations shorter at 0 cm than at 2 cm depth. Temperatures did not differ between microsites during the Ocala fire, but were higher in open microsites during the Archbold fire, probably due to combustion of well-aerated litter. Maximum temperatures of petri dishes were lower than those of adjacent thermocouples due to time required to melt paints. AllEriogonumseeds recovered from petri dishes after the Archbold fire failed to germinate. Germination was quantified forEriogonum floridanumandGarberia heterophyllaseeds heated to C and C under laboratory conditions. Seeds failed to germinate at C, while germination was similar to controls for seeds exposed to C. Results from this study suggest that small-scale spatial variation temperatures at the soil surface during fires is essential for seed survival and subsequent post-fire recruitment.

Sidewall Effects on Heat Transfer Coefficient in a Narrow Impingement Channel

This paper examines the local and averaged effects of channel height in the presence of sidewalls on heat transfer coefficients, with special attention given to the sidewall behavior. High resolution local heat transfer coefficient distributions on target and sidewall surfaces were computed using temperature sensitive paint, recorded via a scientific-grade charge-coupled device camera, and compared with available literature. This is important, as many of the major correlations related to impingement channels are directly applicable to wide arrays of jets, for which the influence of the presence of sidewalls is minimal. Streamwise pressure distributions were recorded and used to explain heat transfer trends and to determine the thermal effectiveness of each channel. Results are presented for average jet-based Reynolds numbers between 17,000 and 45,000. All experiments were carried out on a large-scale single-row 15-hole impingement channel (with an X/D of 5, a Y/D of 4, and a Z/D of 1, 3 and 5). It was observed that available correlations accurately predict the target surface heat transfer coefficients when the influence of the sidewall is minimal, typically at larger channel heights and lower Reynolds numbers. Smaller channel heights tend to outperform larger channels, when considering thermal effectiveness and channel-averaged heat transfer rates, due to the increased heat transfer on the channel sidewalls.

Using Pressure- and Temperature-Sensitive Paint on the Aftbody of a Capsule Entry Vehicle

Pressure-sensitive and temperature-sensitive paint were used to visualize and quantify the surface interactions of reaction control system jets on the aftbody of capsule reentry vehicle shapes. The first model tested was an Apollo-like configuration and was used to focus primarily on the effects of the forward facing roll and yaw jets. The second model tested was an early Orion crew module configuration blowing only out of its forward-most yaw jet, which was expected to have the most intense aerodynamic heating augmentation on the model surface. This paper will present the results from the experiments, which show that with proper system design, both pressure-sensitive and temperature-sensitive paint are effective tools for studying these types of interaction in hypersonic testing environments.

Global Temperature-Sensitive Paint System for Heat Transfer Measurements in Long-Duration Hypersonic Flows

A quantitative global intensity-based temperature-sensitive paint heat transfer measurement system has been developed at Arnold Engineering Development Center Hypervelocity Wind Tunnel No. 9. The system has been designed for use with metal wind-tunnel models in long-duration (on the order of seconds) hypersonic flows. A numerical finite differencing scheme has been proposed for calculating convective heat flux from the paint's surface emission intensity data. As part of the development effort, surface emission intensity data have been collected on a model of a NASA Orion Crew Exploration Vehicle capsule in Mach 10 flow. The proposed data reduction algorithm has been applied to generate high-resolution quantitative heat transfer maps of the model's heat shield. Good quantitative agreement has been achieved between the heat transfer maps and the baseline conventional instrumentation data on the majority of the heat shield surface.

0604 極超音速流中のエアロスパイク付き鈍頭物体の表面熱流束における3次元効果(OS6-1 超音速流と衝撃波,オーガナイズドセッション)

A blunt body in hypersonic flow is subjected to severe aerodynamic heating and drag. This is one of the most critical problems of designing the hypersonic vehicles such as Reusable Launch Vehicles(RLV). It is well known that the spiked-nose(aerospike)concept is effective to reduce aerodynamic drag on asymmetric blunt bodies in hypersonic flow. In this study, we investigated the heat flux distribution on a blunt-nosed body with an aerospike in hypersonic flow. The flow field around a blunt-nosed body is calculated by the full Navier-Stokes simulations to compare with the experimental data such as Schlieren photographs and TSP(Temperature Sensitive Paint)images. It was found that the heat flux distributions changes widely with the angle of attack. Moreover, the correlation between heat flux and the flow and the flow field exists due to the shock/shock interaction patterns for various angle-of-attacks.

Effect of Freestream Noise on Roughness-Induced Transition for the X-51A Forebody

A 20%-scale X-51A forebody model was tested in the Boeing/AFOSR Mach-6 Quiet Tunnel. Repolishing the nozzle throat has restored quiet flow at high Reynolds numbers. The effect of a smooth blank and two different trip strips on windward-forebody transition was measured using temperature-sensitive paint and hot-wire anemometry. Reducing freestream noise from conventional to quiet levels increased the smooth-wall transition Reynolds number by a factor of at least 2.2. In addition, the transition Reynolds number based on the distance from the trips increased by a factor of 2.4 for the smaller trips and by a factor of 1.7 for the larger trips. Thus, tunnel noise had a substantial effect on roughness-induced transition.

Effect of Temperature-Sensitive-Paint Thickness on Global Heat Transfer Measurement in Hypersonic Flow

Heat flux measurement in a hypersonic wind tunnel is one of the necessary requirements for designing the next-generation reentry vehicle. Heat flux is usually calculated from a temporal change in temperature on a model surface. Temperature-sensitive paint provides a global temperature measurement technique based on photochemical reaction. This technique was applied to a hypersonic shock tunnel test, but there were uncertainties caused by the thickness of the temperature-sensitive-paint layer. In this study, the relationship between the temperature-sensitive-paint layer thickness and the measurement accuracy of heat flux was investigated. The models were tested at Mach 10 in the Japan Aerospace Exploration Agency's 0.44-m hypersonic shock tunnel and the heat flux, caused by aerodynamic heating on the model surface, was measured. A comparison between temperature-sensitive-paint data and conventional thermocouple data showed that the measurement error changed with the paint layer thickness. Then a three-dimensional wing-body model was tested to demonstrate the validity of temperature-sensitive paint of an optimized thickness, and a complicated heat flux pattern caused by the shock wave/shock-wave interaction was observed.

A Dual Luminescent Sensor Material for Simultaneous Imaging of Pressure and Temperature on Surfaces

AbstractA novel kind of composite material for simultaneous luminescent determination of air pressure and temperature is presented. The dual sensor consists of a fluorinated platinum porphyrin complex (PtTFPP) as an oxygen‐sensitive probe, and of the highly temperature‐sensitive europium complex Eu(tta)3(dpbt) as temperature probe. Both are incorporated into different polymer microparticles to control response characteristics and to avoid interferences. Encapsulation of PtTFPP in poly(styrene‐co‐acrylonitrile) (PSAN) results in a broad dynamic range from 0.05 to 2.00 bar for pressure measurements. The europium complex was incorporated into poly(vinyl chloride) to reduce the cross sensitivity towards oxygen. This system represents a new class of luminescent sensor system, where the signals are separated via the different luminescence lifetimes of the indicators. It is possible to monitor the emission of the temperature‐sensitive probe by means of time‐resolved fluorescence imaging without interferences, because the luminescence lifetime of the temperature indicator is tenfold longer than that of the oxygen indicator. The temperature image can then be used to compensate cross sensitivity of the pressure indicator towards temperature. In combination with an appropriate time‐resolved measurement technique, this material enables simultaneous imaging of pressure (or oxygen partial pressure) and temperature distributions on surfaces. It is distinguished from other approaches of dual pressure and temperature sensitive paints because it avoids the need of signal separation by application of different cameras or by use of different optical filters or light sources.

Beyond “fire temperatures”: calibrating thermocouple probes and modeling their response to surface fires in hardwood fuels

The maximum temperatures of thermocouples, temperature-sensitive paints, and calorimeters exposed to flames in wildland fires are often called “fire temperatures” but are determined as much by the properties and deployment of the measurement devices as by the fires themselves. Rather than report device temperatures that are not generally comparable among studies, we show that maximum and time-integrated temperatures of relatively thick (4.8 mm diameter) type-K thermocouple probes (TCPs) can be calibrated to estimate fuel consumption and fire line intensity in surface fires. Although reporting standard fire characteristics is an improvement over reporting device temperatures, TCPs are not ideal instruments for monitoring surface fires, because they provide only point estimates of fire behavior and must be calibrated for different fire environments, TCP characteristics, and deployments. To illustrate how TCPs respond to fires and to point the way towards a more general calibration method, we report results from a numerical model that accurately simulated TCP response to a spreading surface fire.

Pressure-Sensitive Paint measurement of the flow around a simplified car model

In applying Pressure-Sensitive Paint (PSP) to low-speed flow wind tunnel testing, it is important to minimize any measurement uncertainties. There are various error sources such as camera noise, misalignment of images due to model displacement and temperature distribution over the model. Among these factors, the effects of temperature distribution change during tests on pressure measurement accuracies were studied in the present paper. Pressure and temperature distributions over a simplified car model (1/10 scale Ahmed model) were measured using PSP and Temperature-Sensitive Paint (TSP). Sequential images were acquired at the same intervals over the entire test period, including for the conditions before and after the tunnel run. As a result, it was found that the measurement error caused by temperature distribution over the model could be reduced using a single-point temperature measurement. In addition, by measuring surface temperature distributions on the model using TSP, it was proved that the most accurate pressure measurement could be made by rationing the wind-off image acquired immediately after shutting down the tunnel to the wind-on image acquired immediately before shutting down the tunnel. Using the present measurement technique, complicated pressure fields over the Ahmed model were successfully visualized.

Application of temperature-sensitive paint for surface temperature measurement in heat transfer enhancement applications

This paper introduces the use of temperature-sensitive paint (TSP) to obtain the whole-field temperature distributions in heat transfer enhancement applications. Knowing the surface temperatures in such applications is important to quantify the heat transfer, as well as to obtain insight into the flow physics. Applying the TSP to a flat plate with and without a vortex generator showed that the TSP Nusselt number distribution over the flat plate alone matched the Blasius solution with less than 10% error. The TSP temperature distribution of the flat plate with the delta wing vortex generator showed a local heat transfer enhancement of about 30% and the locations of temperature extremes. This paper also provides a detailed guideline for the application, image acquisition, and image processing procedures for TSP along with its calibration surfaces.

Application of pressure and temperature sensitive paints for study of heat transfer to a circular impinging air jet

Experimental and computational studies are performed to study pressure and temperature distributions and flow patterns on impingement target surface subject to a single impinging air jet from a plenum. The experiments cover a range of jet-to-target plate distance, Z / D , from 1.5 to 12 for Reynolds number range from 10 000 to 60 000. The main objective is to investigate the optimal jet-to-target distance ( Z / D ) for stagnation point heat transfer and location of second peak in local heat transfer at small Z / D value under the current jet impingement configuration. Pressure and temperature sensitive paints measurements techniques are implemented to obtain the distribution of pressure and temperature on target surface. The optimal separation distance ( Z / D ) for stagnation region Nu is found to be about 5. The location of the second peak in local Nu for Z / D of 1.5 is at radial location ( r / D ) of about 1.8. The area averaged Nusselt numbers are compared to those calculated using correlation from open literature. The agreement varies with Z / D and jet Reynolds number. Experimental results are also compared to computational (CFD) prediction using realizable k– ε turbulence model.

A109 流体計測のための担持型TSPの開発とPSPへの応用

In this paper, current status of the development of luminophore-pendant temperature-sensitive paint of poly[l-(trimetylsilyl)phenyl-2-phenylacetylene] (PTMST) is discussed. PTMST uses poly(l-trimethylsilyl-l-propyne) (PTMSP) based polymer, which is known as one of the highest gas permeable polymers. Because of its high gas permeability and single luminescent compound, we can expect fast response of PTMST to the change in temperature and pressure of the test gas. We can also create PTMST-based two-color PSP for temperature-compensated pressure sensor by simply mixing pressure-sensitive luminophore in PTMST. In this paper, we mix platinum tetrakis (pentafluorophenyl) porphyrin (PtTFPP) as a pressure-sensitive luminophore to create PTMST-based two-color PSP (PtTFPP-PTMST). Spectral analysis shows that PtTFPP-PTMST provides temperature sensitive peak of PTMST (around 540 nm) and pressure sensitive peak of PtTFPP (around 650 nm), which can be separated by band-pass filters. We have calibrated PTMST from 100 K to 373 K as well as PtTFPP-PTMST from 120 K to 333 K to study the static characteristics of these sensors. PTMST provides the temperature sensitivity over the calibrated range, giving the maximum value of 2.72%/K at 100 K. PTMST itself is almost pressure independent. Pressure sensitivity of PtTFPP-PTMST is 0.26%/kPa at 293 K. PtTFPP-PTMST shows pressure sensitivity of 0.66%/kPa even at cryogenic temperature of 120 K. The unsteady characteristic of PtTFPP-PTMST is determined using a step response to a pressure change caused by a shock tube. The response time of PtTFPP-PTMST is on the order of milliseconds. A demonstration of PTMST at cryogenic measurement is shown by transition detection of PTMST-coated NACA64A012 model in JAXA 0.1m Transonic Cryogenic Wind Tunnel. PTMST detects a natural transition as well as a forced transition induced by a roughness at the leading edge at Mach 0.4, total temperature 200 K, and total pressure 120 kPa.

Sensitivity Analysis of Three-Gate Lifetime Pressure- and Temperature-Sensitive Paint Measurements

Sensitivity Analysis of Three-Gate Lifetime Pressure- and Temperature-Sensitive Paint Measurements

Experimental Study of Underexpanded Supersonic Jet Impingement on an Inclined Flat Plate

Flowfields of the M2.2 jet impinging on an inclined flat plate at various plate angles, nozzle-plate distances, and pressure ratios are experimentally investigated using pressure-sensitive paints and Schlieren flow visualization. The effect of temperature variation on the flat plate is eliminated by the calibration using temperature-sensitive paints. A comparison with the former experiment shows that the current pressure-sensitive paint measurement produces reliable data sufficient for the flowfield discussion under consideration. The pressure-sensitive paints and Schlieren images obtained in the experiment suggest that the flowfields at various flat plate angles, nozzle-plate distances, and pressure ratios can all be classified into three types of flow structure. Within the range of geometrical and flow conditions considered in the present paper, the flowfield patterns can be predicted without experiments if the shock cell length in the freejet for various pressure ratios is known in advance. Extensive studies for a wide range of geometrical and physical parameters became feasible with a new efficient pressure/temperature-sensitive paint measurement technique showing surface pressure map with much less effort compared to conventional pressure tap measurement.

C209 極超音速空力加熱率計測におけるTSP皮膜の影響

Heat flux measurement in a hypersonic wind tunnel is one of indispensable requirements for designing the next generation re-entry vehicle. Heat flux is usually calculated from a temporal change in temperature on the model surface. Temperature-Sensitive Paint (TSP) is a global temperature measurement technique based on photochemical reaction. This technique was applied to a hypersonic shock tunnel test, but there existed uncertainties caused by TSP layer thickness. In this study, the relationship between TSP layer thickness and measurement accuracy in heat flux was investigated by experiment. The models were tested at Mach 10 in the JAXA 0.44-m Hypersonic Shock Tunnel and heat flux caused by aerodynamic heating on the model surface was measured. A comparison between TSP data and conventional thermocouple data showed that the measurement error changed with the layer thickness in nonlinear fashion. To demonstrate the capability of TSP with the optimized thickness, tests using a 3-dimensional wing-body model have been conducted and the complicated heat flux pattern caused by shock-wave/shock-wave interaction has been observed.

Image measurements of unsteady pressure fluctuation by a pressure-sensitive coating on porous anodized aluminium

Pressure-sensitive luminescent coating on porous anodized aluminium (AA-PSP) was applied to measure non-periodic unsteady pressure distribution on a wind-tunnel model. A high-speed digital video camera was used to capture the PSP signal. The pressure-sensitive dye was tris(4,7-diphenylphenanthroline) ruthenium(II) ([Ru(dpp)3]2+). The coating has a short response time of O(10 µs), although it exhibits temperature and humidity sensitivities. A hydrophobic coating was applied on the anodized aluminium surface to suppress the humidity sensitivity. A temperature sensitive paint was used to obtain the temperature distribution instantaneously with the pressure. The temperature data were used to correct the PSP response. An appropriate data acquisition procedure as well as digital image processing algorithm was established to compensate for the error from the temperature and humidity sensitivities. The present system was applied to measure the pressure distribution on a delta wing at a high angle of attack in transonic flow, whose flow is unsteady due to the interaction between shock waves and leading edge vortices. The non-periodic unsteady pressure distribution on the delta wing was successfully measured with the sampling rate of 1 kHz and within a few per cent error in absolute pressure level.