Journal articles: 'Dynamic IR thermography'

1

Wei, Wei, Jian Wei Yu, Tao You, Xiao Fen Yu, and Yong Hong Wang. "Evaluation of the Transient Temperature Distribution of End-Face Sliding Friction Pair Using Infrared Thermometry." Key Engineering Materials 613 (May 2014): 213–18. http://dx.doi.org/10.4028/www.scientific.net/kem.613.213.

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A real-time temperature measurement system was designed for end-face sliding friction pairs with an infrared (IR) probe and IR thermography installed on it. The approximate temperature of contact surface was measured by the probe while non-contact surface’s temperature distribution was determined with the IR thermography. Two experiments with constant load but varied rotational speeds were carried out, and a preliminary study was made to analyze the variation of temperature in the friction process. Furthermore, the probe data was used as thermal load to calculate the temperature field by the FEM model and the result was verified using IR images. The experimental results showed that the infrared measurement system can detect and record the interface-temperature variation accurately. The probe data showed a good dynamic performance with the variation of friction coefficient. In addition, the calculated temperature field showed good accordance with the IR thermography data.

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Mutschler, Robin, and Emanuele Moioli. "Infrared Thermography as an Operando Tool for the Analysis of Catalytic Processes: How to Use it?" Catalysts 11, no. 3 (February 26, 2021): 311. http://dx.doi.org/10.3390/catal11030311.

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Infrared (IR) thermography is a powerful tool to measure temperature with high space and time resolution. A particularly interesting application of this technology is in the field of catalysis, where the method can provide new insights into dynamic surface reactions. This paper presents guidelines for the development of a reactor cell that can aid in the efficient exploitation of infrared thermography for the investigation of catalytic and other surface reactions. Firstly, the necessary properties of the catalytic reactor are described. Secondly, we analyze the requirements towards the catalytic system to be directly observable by IR thermography. This includes the need for a catalyst that provides a sufficiently high heat production (or absorption) rate. To achieve true operando investigation conditions, some dedicated equipment must be developed. Here, we provide the guidelines to assemble a chemical reactor with an IR transmitting window through which the reaction can be studied with the infrared camera along with other best practice tips to achieve results. Furthermore, we present selected examples of catalytic reactions that can be monitored by IR thermography, showing the potential of the technology in revealing transient and steady state chemical phenomena.

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Stankovičová, Zuzana, Vladimír Dekýš, Milan Uhríčik, Pavol Novák, and Bohumír Strnadel. "Fatigue limit estimation using IR camera." MATEC Web of Conferences 157 (2018): 05021. http://dx.doi.org/10.1051/matecconf/201815705021.

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Determination of fatigue limit by traditional method is associated with testing of large number of specimens. This is caused by more scatter in test results and therefore a higher amount of tests are needed to generate a statistically reliable trend. The paper presents rapid and reliable estimation of fatigue limit using infrared thermography. By analysing the temperature of the material surface during cyclic loading it is possible to evaluate the dynamic behaviour of a structure and determine the fatigue limit. The method provides reliable results using a very little number of specimens in a very short time compared with traditional method.

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Kashyap, Uddip, Subhasish Sarkar, and Sandip K. Saha. "Study of hot stress dynamic IR thermography for detecting surface cancerous tissue." Journal of Medical Engineering & Technology 44, no. 6 (June 16, 2020): 284–98. http://dx.doi.org/10.1080/03091902.2020.1772390.

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Steenackers, Verstockt, Cloostermans, Thiessen, Ribbens, and Tjalma. "Infrared Thermography for DIEP Flap Breast Reconstruction Part I: Measurements †." Proceedings 27, no. 1 (December 3, 2019): 48. http://dx.doi.org/10.3390/proceedings2019027048.

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In order to identify the exact location of a useful perforator for DIEP flap breast reconstruction, CT images are made in the pre-operative phase. The aim of this research is to evaluate if dynamic infrared thermography is a helpful tool to check and visualize the blood flow in the flap during the pre- and peroperative phase. The results will be used in order to pinpoint the usefulness of IR thermography as an alternative method for perforator mapping and flapdesign. By means of infrared thermography the blood vessel distribution and its vascularisation of the abdominal wall will be visualized. The thermal images can help to detect the correct perforator and can help to decide which parts of the flap are best perfused and can be used for the DIEP flap reconstruction.

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Chevalier, Florian, Javier Leon, X. Perpiña, Dominique Tournier, Xavier Jordá, Josep Montserrat, and Phillippe Godignon. "IR Lock-In Thermography Analysis to Evidence Dynamic Mis-Behavior of SiC Device Prototypes." Materials Science Forum 821-823 (June 2015): 801–5. http://dx.doi.org/10.4028/www.scientific.net/msf.821-823.801.

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This paper deals with the geometry of a high voltage (1200 V) vertical JFET made with 4H silicon carbide, inspired by SIT or commercial solutions like Semisouth's one (principle exposed in Fig. 1). A first layout was designed allowing an easy integration of a free-wheeling diode. Indeed with the maturity of SiC JFET fabrication process, nowadays' trend is the high integration level of a complete power electronics system. This paper will focus on the distribution of the gate potential or the source current across the device and the relation that could be done with the switching delay. The measurements start with the classical I–V static characterization from room temperature till 225°C. After packaging the best dies, the switching behavior is studied. Gate bias and temperature dependence is also investigated. In order to fully understand the conducting/blocking or switching mechanisms, some further measurements using lock-in infrared thermography (LIRT) technique was led. Thus, with this complete characterization methodology the device layout can be improved.

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Chernov, G., J. L. Ibarra-Valdez, R. C. Carrillo-Torres, T. C. Medrano-Pesqueira, V. Chernov, and M. Barboza-Flores. "Improved Method of Study on the Photothermal Effect of Plasmonic Nanoparticles by Dynamic IR Thermography." Plasmonics 14, no. 4 (November 21, 2018): 935–44. http://dx.doi.org/10.1007/s11468-018-0877-1.

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Sadeghi, Maryam, Axel Boese, Ivan Maldonado, Michael Friebe, Joerg Sauerhering, Simon Schlosser, Heinrich Wehberg, and Konrad Wehberg. "Feasibility test of Dynamic Cooling for detection of small tumors in IR thermographic breast imaging." Current Directions in Biomedical Engineering 5, no. 1 (September 1, 2019): 397–99. http://dx.doi.org/10.1515/cdbme-2019-0100.

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AbstractThermographic imaging is a known technology to detect temperature differences. For medical applications, the patterns of heat distribution are used for diagnosis. It is already tested to visualize blood supply, inflammatory processes, and superficial or more extensive tumors, e.g. in the breast tissue. This method was promoted for breast screening purposes and as a substitute for mammography for mid aged women, but the results were not convincing for younger women, where tissue density is higher, tumor growth is often connected to local temperature increase and radiation-based mammography is not an option. Infrared (IR) thermography can support tumor screening. The screening should allow the early detection of small lesions even in the depth. Therefor we evaluated the feasibility of dynamic cooling in combination with IR imaging in a phantom study. A temperature-controllable gel phantom including a heating plate, a depth-adjustable heat source mimicking a tumor, and three sensors for temperature monitoring was built up. A raspberry pi device serves as a control unit to create a stable temperature balance comparable to a human breast. For the experiments, the tumor was placed in various depth. After cooling, the thermal recovery phase of the phantom was imaged using an IR camera and a webcam. A pixel-wise analysis of the IR data detects a higher gradient of temperature change in the tumor region. The experiments demonstrated the feasibility of tumor detection based on dynamic cooling and IR imaging.

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Forcellese, Archimede, Milena Martarelli, Giuseppe Pandarese, and Michela Simoncini. "Similar and Dissimilar FSWed Joints in Lightweight Alloys: Heating Distribution Assessment and IR Thermography Monitoring for On-Line Quality Control." Key Engineering Materials 554-557 (June 2013): 1055–64. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.1055.

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The heating distribution assessment on similar and dissimilar friction stir welded joints in AA6082 and AA5754 aluminium alloy sheets was investigated. The FSW experiments were carried out using constant rotational and welding speeds of 1500 rpm and 60 mm/min, respectively. Temperature was locally measured by means of K-type thermocouples inserted into thin grooves located on the bottom side of the sheets, in fixed positions, very close to the welding line. It was observed that the mechanical properties of joints are related to the heat distribution. In order to obtain a completely non intrusive temperature monitoring, that was able to follow the process dynamic, a non-contact measurement system based on infrared thermography was also developed. Such system, used for the experimental evaluation of temperature on the upper surface of the joints, is also able to detect the presence of flow defects with a non-destructive method, demonstrating its effectiveness as a diagnostic instrument for the on-line quality control of welded joints.

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Sigal, V. I., and T. E. Shumakova. "Unsteady-state thermophysical models for detection of physiological and pathological conditions of the kidney by methods of active dynamic IR thermography." Journal of Engineering Physics and Thermophysics 71, no. 3 (May 1998): 519–24. http://dx.doi.org/10.1007/bf02682537.

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11

Delaney, Kara M., Alexander Gorbach, Nitin Malik, Jordan Maivelett, Yuen Yi Hon, Dihua Xu, Enrico M. Novelli, et al. "Blood Flow Is Increased in Wounds and Peri-Wound Area by Laser Speckle Contrast Imaging and Infrared Thermography in Adults with Sickle Cell Leg Ulcers." Blood 120, no. 21 (November 16, 2012): 1009. http://dx.doi.org/10.1182/blood.v120.21.1009.1009.

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Abstract Abstract 1009 Background: Leg ulcerations are a serious and debilitating complication of sickle cell disease (SCD) and other hemolytic anemias, whose etiology is not completely understood. Wound healing involves an ordered progression of vasoconstriction (hemostatic phase), followed by vasodilatation (inflammatory and proliferative phase) and epithelialization. Little is known about the changes in the microcirculation of chronic wounds in patients with sickle cell disease. Endothelial function affects microcirculation and regulates blood flow. Endothelial dysfunction is a recognized pathway to end organ dysfunction in SCD. Laser speckle contrast imaging (LSCI) and Infrared Thermography (IR) are non-invasive technique used to assess dynamic changes in blood flow in response to vaso-reactive and other insults in both health and disease, while peripheral arterial tonometry is utilized for early detection of cardiovascular disease. The aim of this study was to evaluate skin's microvasculature response and endothelial function in adults with HbSS and chronic leg ulceration. Methods: Twelve adults with HbSS and chronic leg ulcers (> 1 month duration) were evaluated at steady state with a detailed medical and ulcer history, physical examination, and clinical labs. Clinical and laboratory data were compared to 269 adults with Hb SS, without active leg ulcers, enrolled in a Pulmonary Hypertension screening protocol (Clin trial no. NCT00011648). Blood flow (LCSI) and IR measurements of the ulcer bed, the peri-ulcer area and of a distant, unaffected area (baseline) were obtained and compared. Peripheral arterial tonometry (PAT) was obtained to calculate the ratio of post-occlusion dilatation to baseline reactive hyperemia index: RHI. An RHI>1.67 is indication of normal endothelial function. Results: Mean age for the 12 subjects with chronic active leg ulcer: 31 years ± 11yrs, 5 male, 5 had a history of trauma. When compared to SS patients without active leg ulcers: mean MAP 82 vs 103 mmHg (p <0.0001), Hb 7.6 vs 9.0 g/dL (p=0.001), and LDH 533 vs. 375 (p=0.023). CRP was higher, 9.4 vs 0.81(p<0.0001), Arginine/ornithine ratio was lower (0.66 vs. 1.06) in patients with active leg ulcers (p=0.005). Thrombophila w/u was negative in 11, but half of patients were on anticoagulation for previous PE/DVT's. A third of the patients had been admitted for VOC in the previous 12 months and 11/12 were taking daily opioids. Blood flow was highest in the ulcer center: 731+421, with progressively lesser flow measurements in the periwound: 370+157 and in the distal region(or baseline) 165+89. Temperature, as measured by IR, was higher (34.9 C°) in the periwound area than in the distant, or baseline area (34.5 C°) (p <0.03). Blunted RHI on PAT was seen in 5/12 subjects, with values <1.67. Conclusions: With this study we confirm that patients with HbSS and leg ulcers represent a subgroup with severe disease, as demonstrated by the high use of HU and/or transfusion, and number of complications at a relatively young age. We report high blood flow in the ulcer bed and immediate surrounding regions, compared to unaffected areas, never prior demonstrated. It is probable that the increase in blood flow observed in the wound and peri-wound regions reflect s a high vasodilated state, resulting from severe anemia, relative hypotension, and chronic inflammation. Laboratory and clinical data supports the presence of a persistent inflammatory and hemolytic state, as well as low arginine bioavailabitlity. Laser Speckle Contrast Imaging, Infrared Thermography and Peripheral Arterial Tonometry are effective, non invasive novel techniques useful for studying microvascular and endothelial function in patients with SCD and leg ulcers. Disclosures: No relevant conflicts of interest to declare.

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Singh, Jaspreet, Sachin Kumar, and Ajat Shatru Arora. "Thermographic evaluation of mindfulness meditation using dynamic IR imaging." Infrared Physics & Technology 95 (December 2018): 81–87. http://dx.doi.org/10.1016/j.infrared.2018.10.029.

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Mormile, P., L. Petti, M. Rippa, B. Immirzi, M. Malinconico, and G. Santagata. "Monitoring of the degradation dynamics of agricultural films by IR thermography." Polymer Degradation and Stability 92, no. 5 (May 2007): 777–84. http://dx.doi.org/10.1016/j.polymdegradstab.2007.02.015.

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Nizovtsev, Mikhail, Alexey Sterlyagov, and Viktor Terekhov. "Dynamics of thermal and moistening fronts in porous material under capillary moistening." Thermal Science 17, no. 4 (2013): 1071–78. http://dx.doi.org/10.2298/tsci121218060n.

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IR thermography and gamma-ray method were used to experimentally study motion of thermal and moistening fronts in a porous material under capillary moistening. It is shown that at capillary moistening propagation of the moistening front may be accompanied by the thermal front due to sorption processes. On the basis of obtained experimental data the relation between propagation of two fronts has been established.

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Fabien, Girard, Mickaël Antoni, and Khellil Sefiane. "Use of IR Thermography To Investigate Heated Droplet Evaporation and Contact Line Dynamics." Langmuir 27, no. 11 (June 7, 2011): 6744–52. http://dx.doi.org/10.1021/la104962m.

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Kellow, J., and E. E. Wolf. "In-situ IR thermography studies of reaction dynamics during CO oxidation on Rh-SiO2 catalysts." Catalysis Today 9, no. 1-2 (March 1991): 47–51. http://dx.doi.org/10.1016/0920-5861(91)85006-t.

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Figueiredo, Miguel, Guido Marseglia, Ana S. Moita, Miguel R. O. Panão, Ana P. C. Ribeiro, Carlo M. Medaglia, and António L. N. Moreira. "Thermofluid Characterization of Nanofluid Spray Cooling Combining Phase Doppler Interferometry with High-Speed Visualization and Time-Resolved IR Thermography." Energies 13, no. 22 (November 10, 2020): 5864. http://dx.doi.org/10.3390/en13225864.

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Spray impingement on smooth and heated surfaces is a highly complex thermofluid phenomenon present in several engineering applications. The combination of phase Doppler interferometry, high-speed visualization, and time-resolved infrared thermography allows characterizing the heat transfer and fluid dynamics involved. Particular emphasis is given to the use of nanofluids in sprays due to their potential to enhance the heat transfer mechanisms. The results for low nanoparticle concentrations (up to 1 wt.%) show that the surfactant added to water, required to stabilize the nanofluids and minimize particle clustering, affects the spray’s main characteristics. Namely, the surfactant decreases the liquid surface tension leading to a larger wetted area and wettability, promoting heat transfer between the surface and the liquid film. However, since lower surface tension also tends to enhance splash near the edges of the wetted area, the gold nanospheres act to lessen such disturbances due to an increase of the solutions’ viscosity, thus increasing the heat flux removed from the spray slightly. The experimental results obtained from this work demonstrate that the maximum heat convection coefficients evaluated for the nanofluids can be 9.8% to 21.9% higher than those obtained with the base fluid and 11.5% to 38.8% higher when compared with those obtained with DI water.

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Gerasimova, E. I., O. A. Plekhov, O. B. Naĭmark, and I. A. Panteleev. "Methods of analyzing the temperature dynamics of the human body from the data of IR thermography and their use in diagnosing breast cancer." Journal of Optical Technology 80, no. 6 (June 1, 2013): 400. http://dx.doi.org/10.1364/jot.80.000400.

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Larciprete, Maria Cristina, Stefano Paoloni, Gianmario Cesarini, Concita Sibilia, Vitalija Rubežienė, and Audrone Sankauskaitė. "Thermo-regulating properties of textiles with incorporated microencapsulated Phase Change Materials." MRS Advances 5, no. 18-19 (2020): 1023–28. http://dx.doi.org/10.1557/adv.2020.106.

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ABSTRACTPhase change materials (PCMs) are getting increasing interest due to their capacity to absorb, store and release heat energy. Their effectiveness is characterized by quantities of absorbed/released heat energy, expressed as enthalpy. Specifically, the larger is the enthalpy, the more efficient thermoregulation effect is achieved. With this in mind, PCMs can be used in the manufacture of thermally regulated clothing in order to minimize heat strain and simultaneously improve thermal comfort. Moreover, such materials also modify their infrared radiation emission during phase transition, thus they can be envisioned to exploit thermal shielding applications. The aim of the present research was to investigate the infrared emissivity of textiles composed by cotton yarns with dispersed PCMs. The organic microcapsules of phase change materials, having different binding to the fibre mechanisms, were padded onto the fabric surface by pad-dry-cure method. The thermal properties and stabilities were measured using differential scanning calorimetry, while infrared emissivity was characterized using infrared thermographic technique. The obtained experimental results show a dynamic tuning of IR emissivity during heating/cooling process which can be correlated to the type and properties (enthalpy of fusion) of the corresponding PCM.

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Volovik, M. G., G. E. Sheiko, and A. N. Kuznetsov. "Thermographic signs of spastic type cerebral palsy in 4–7 years old children: protocol and data analysis." Medical alphabet 3, no. 24 (November 20, 2019): 28–38. http://dx.doi.org/10.33667/2078-5631-2019-3-24(399)-28-38.

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31 children at the age of 4–7 years with two spastic forms of cerebral palsy (G80.1 and G80.2) with the degree of motor dysfunction of levels 1 and 2 according to GMFCS were examined using IR thermal imaging. For the first time, the temperature distribution on the limbs and its dynamics in response to the dosed motor load on the spastic muscle groups are described in detail. For the group of patients with hemiparesis characterized by asymmetry of temperature on the limbs associated with the side of the lesion, and for the group with diplegia — the inversion of the normal proximal-distal gradient, most pronounced in the segments of the shin / foot and shoulder / forearm and less in the forearm / wrist, and abnormally high temperature difference on the back between the thoracic and lumbar regions. Moderate physical activity leads to the enhancement of thermal anomalies due to the additional reduction of the temperature in the projection of the affected muscles and strengthen the pathological symptoms. Knowledge of the skin thermal reactions in the projection of these muscles in response to motor tests opens up a potential opportunity to use the method in assessing the results of treatment and rehabilitation of patients with cerebral palsy.

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Frodella, William, Giacomo Lazzeri, Sandro Moretti, Jacob Keizer, and Frank G. A. Verheijen. "Applying Infrared Thermography to Soil Surface Temperature Monitoring: Case Study of a High-Resolution 48 h Survey in a Vineyard (Anadia, Portugal)." Sensors 20, no. 9 (April 25, 2020): 2444. http://dx.doi.org/10.3390/s20092444.

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The soil surface albedo decreases with an increasing biochar application rate as a power decay function, but the net impact of biochar application on soil temperature dynamics remains to be clarified. The objective of this study was to assess the potential of infrared thermography (IRT) sensing by monitoring soil surface temperature (SST) with a high spatiotemporal and thermal resolution in a scalable agricultural application. We monitored soil surface temperature (SST) variations over a 48 h period for three treatments in a vineyard: bare soil (plot S), 100% biochar cover (plot B), and biochar-amended topsoil (plot SB). The SST of all plots was monitored at 30 min intervals with a tripod-mounted IR thermal camera. The soil temperature at 10 cm depth in the S and SB plots was monitored continuously with a 5 min resolution probe. Plot B had greater daily SST variations, reached a higher daily temperature peak relative to the other plots, and showed a faster rate of T increase during the day. However, on both days, the SST of plot B dipped below that of the control treatment (plot S) and biochar-amended soil (plot SB) from about 18:00 onward and throughout the night. The diurnal patterns/variations in the IRT-measured SSTs were closely related to those in the soil temperature at a 10 cm depth, confirming that biochar-amended soils showed lower thermal inertia than the unamended soil. The experiment provided interesting insights into SST variations at a local scale. The case study may be further developed using fully automated SST monitoring protocols at a larger scale for a range of environmental and agricultural applications.

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Granero-Belinchon, Carlos, Aurelie Michel, Veronique Achard, and Xavier Briottet. "Spectral Unmixing for Thermal Infrared Multi-Spectral Airborne Imagery over Urban Environments: Day and Night Synergy." Remote Sensing 12, no. 11 (June 9, 2020): 1871. http://dx.doi.org/10.3390/rs12111871.

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TRUST (Thermal Remote sensing Unmixing for Subpixel Temperature) is a spectral unmixing method developed to provide subpixel abundances and temperatures from radiance images in the thermal domain. By now, this method has been studied in simple study cases, with a low number of endmembers, high spatial resolutions (1 m) and more than 30 spectral bands in the thermal domain. Thus, this article aims to show the applicability of TRUST on a highly challenging study case: the analysis of a heterogeneous urban environment with airborne multispectral (eight thermal bands) images at 8-m resolution. Thus, this study is necessary to generalize the use of TRUST in the analysis of urban thermography. Since TRUST allows linking intrapixel temperatures to specific materials, it appears as a very useful tool to characterize Surface Urban Heat Islands and its dynamics at high spatial resolutions. Moreover, this article presents an improved version of TRUST, called TRUST-DNS (Day and Night Synergy), which takes advantage of daytime and nighttime acquisitions to improve the unmixing performances. In this study, both TRUST and TRUST-DNS were applied on daytime and nighttime airborne thermal images acquired over the center of Madrid during the DESIREX (Dual-use European Security IR Experiment) campaign in 2008. The processed images were obtained with the Aircraft Hyperspectral Scanner (AHS) sensor at 4-m spatial resolution on 4 July. TRUST-DNS appears to be more stable and slightly outperforms TRUST on both day and night images. In addition, TRUST applied on daytime outperforms TRUST on nighttime, illustrating the importance of the temperature contrasts during day for thermal unmixing.

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Simon, Bernhard, Adrian Filius, Cameron Tropea, and Sven Grundmann. "IR thermography for dynamic detection of laminar-turbulent transition." Experiments in Fluids 57, no. 5 (May 2016). http://dx.doi.org/10.1007/s00348-016-2178-9.

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Rokita, E., T. Rok, and G. Tatoń. "Evaluation of allergic response using dynamic thermography." Opto-Electronics Review 23, no. 1 (January 1, 2015). http://dx.doi.org/10.1515/oere-2015-0007.

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AbstractSkin dynamic termography supplemented by a mathematical model is presented as an objective and sensitive indicator of the skin prick test result. Termographic measurements were performed simultaneously with routine skin prick tests. The IR images were acquired every 70 s up to 910 s after skin prick. In the model histamine is treated as the principal mediator of the allergic reaction. Histamine produces vasolidation and the engorged vessels are responsible for an increase in skin temperature. The model parameters were determined by fitting the analytical solutions to the spatio-temporal distributions of the differences between measured and baseline temperatures. The model reproduces experimental data very well (coefficient of determination = 0.805÷0.995). The method offers a set of parameters to describe separately skin allergic reaction and skin reactivity. The release of histamine after allergen injection is the best indicator of allergic response. The diagnostic parameter better correlates with the standard evaluation of a skin prick test (correlation coefficient = 0.98) than the result of the thermographic planimetric method based on temperature and heated area determination (0.81). The high sensitivity of the method allows for determination of the allergic response in patients with the reduced skin reactivity.

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Villasmil, W., A. Meier, and A. Steinfeld. "Dynamic Modeling of a Solar Reactor for Zinc Oxide Thermal Dissociation and Experimental Validation Using IR Thermography." Journal of Solar Energy Engineering 136, no. 1 (October 24, 2013). http://dx.doi.org/10.1115/1.4025511.

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A dynamic numerical model of a solar cavity-type reactor for the thermal dissociation of ZnO is formulated based on a detailed radiative heat transfer analysis combining the Monte Carlo ray-tracing technique and the radiosity enclosure theory. The quartz window is treated as a semitransparent glass layer with spectrally and directionally dependent optical properties. Model validation is accomplished by comparison with experimental results obtained with a 10-kW solar reactor prototype in terms of cavity temperatures, reaction extents, and quartz window temperature distribution measured by IR thermography. The solar-to-fuel energy conversion efficiencies obtained experimentally are reported, and the various energy flows are quantified.

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Jonsson, Isak, Srikanth Deshpande, Valery Chernoray, Oskar Thulin, and Jonas Larsson. "Experimental and Numerical Study of Laminar-Turbulent Transition on a Low-Pressure Turbine Outlet Guide Vane." Journal of Turbomachinery 143, no. 10 (May 19, 2021). http://dx.doi.org/10.1115/1.4050629.

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Abstract This work presents an experimental and numerical investigation of the laminar-turbulent transition and secondary flow structures in a turbine rear structure (TRS). The study was executed at engine representative Reynolds number and inlet conditions at three different turbine load cases. Experiments were performed in an annular rotating rig with a shrouded low-pressure turbine upstream of the TRS test section. The numerical results were obtained using the shear stress transport k − ω turbulence model and the Langtry–Menter γ − θ transition model. The boundary layer transition location at the entire vane suction side is investigated. The location of the onset and the transition length are measured using IR-thermography along the entire vane span. The IR-thermography approach was validated using hot-wire boundary layer measurements. Both experiments and computational fluid dynamics (CFD) show large variations of transition location along the vane span with strong influences from endwalls and turbine outlet conditions. Both agree well with traditional transition onset correlations near midspan and show that the transition onset Reynolds number is independent of the acceleration parameter. However, CFD tends to predict an early transition onset in the midspan vane region and a late transition is present in the hub region. Furthermore, in the hub region, CFD is shown to overpredict the transverse flow and related losses.

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El-Gabry, Lamyaa A., Douglas R. Thurman, Philip E. Poinsatte, and James D. Heidmann. "Detailed Velocity and Turbulence Measurements in an Inclined Large-Scale Film Cooling Array." Journal of Turbomachinery 135, no. 6 (September 13, 2013). http://dx.doi.org/10.1115/1.4023347.

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A large-scale model of an inclined row of film cooling holes is used to obtain detailed surface and flow field measurements that will enable future computational fluid dynamics code development and validation. The model consists of three holes of 1.9-cm diameter that are spaced three hole diameters apart and inclined 30 deg from the surface. The length to diameter ratio of the coolant holes is about 18. Measurements include film effectiveness using IR thermography and near wall thermocouples, heat transfer using liquid crystal thermography, flow field temperatures using a thermocouple, and velocity and turbulence quantities using hotwire anemometry. Results are obtained for blowing ratios of up to 2 in order to capture severe conditions in which the jet is lifted. For purposes of comparison with prior art, measurements of the velocity and turbulence field along the jet centerline are made and compare favorably with two data sets in the open literature thereby verifying the test apparatus and methodology are able to replicate existing data sets. In addition, a computational fluid dynamics model using a two-equation turbulence model is developed, and the results for velocity, turbulent kinetic energy and turbulent dissipation rate are compared with experimentally derived quantities.

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Lu, Yi, Hui Fang, Jiming Bao, and Dong Liu. "Dynamics of a Leidenfrost Droplet Modulated by Electrowetting." Journal of Heat Transfer 139, no. 8 (June 5, 2017). http://dx.doi.org/10.1115/1.4036876.

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Leidenfrost phenomenon is closely related to film boiling and the critical heat flux (CHF) limit of boiling heat transfer. Understanding the mechanisms of Leidenfrost phenomenon and devising effective ways to suppress it is of great interest to the heat transfer enhancement community. In this work, a synchronized high-speed optical imaging and infrared (IR) thermography approach was employed to investigate the dynamics of a Leidenfrost droplet under the influence of electrowetting (EW). The Leidenfrost droplet was produced by dispensing a water drop on a Teflon-coated silicon wafer maintained at a wall temperature of Twall = 200 °C. Both direct-current (DC) and alternating-current (AC) electric fields were applied to induce EW effect to suppress the Leidenfrost state. The interfacial instabilities of the Leidenfrost droplet were observed, and the instantaneous temperature and heat flux distributions on the heating surface were measured. The results suggest that the electrical forces destabilize the liquid-vapor interface and cause the vapor film that insulates the heating surface from the droplet to collapse. Re-establishment of the liquid-solid contact helps to drastically improve the heat transfer, as evidenced by the reduced surface temperature and the enhanced heat flux.

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29

Ornano, Francesco, and Thomas Povey. "Experimental and Computational Study of the Effect of Momentum-Flux Ratio on High-Pressure Nozzle Guide Vane Endwall Cooling Systems." Journal of Turbomachinery 139, no. 12 (September 26, 2017). http://dx.doi.org/10.1115/1.4037756.

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High-pressure (HP) nozzle guide vane (NGV) endwalls are often characterized by highly three-dimensional (3D) flows. The flow structure depends on the incoming boundary layer state (inlet total pressure profile) and the (static) pressure gradients within the vane passage. In many engine applications, this can lead to strong secondary flows. The prediction and design of optimized endwall film cooling systems is therefore challenging and is a topic of current research interest. A detailed experimental investigation of the film effectiveness distribution on an engine-realistic endwall geometry is presented in this paper. The film cooling system was a fairly conventional axisymmetric double-row configuration. The study was performed on a large-scale, low-speed wind tunnel using infrared (IR) thermography. Adiabatic film effectiveness distributions were measured using IR cameras, and tests were performed across a wide range of coolant-to-mainstream momentum-flux and mass flow ratios (MFRs). Complex interactions between coolant film and vane secondary flows are presented and discussed. A particular feature of interest is the suppression of secondary flows (and associated improved adiabatic film effectiveness) beyond a critical momentum flux ratio. Jet liftoff effects are also observed and discussed in the context of sensitivity to local momentum flux ratio. Full coverage experimental results are also compared to 3D, steady-state computational fluid dynamics (CFD) simulations. This paper provides insights into the effects of momentum flux ratio in establishing similarity between cascade conditions and engine conditions and gives design guidelines for engine designers in relation to minimum endwall cooling momentum flux requirements to suppress endwall secondary flows.

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Lu, Yiping, Alok Dhungel, Srinath V. Ekkad, and Ronald S. Bunker. "Film Cooling Measurements for Cratered Cylindrical Inclined Holes." Journal of Turbomachinery 131, no. 1 (October 2, 2008). http://dx.doi.org/10.1115/1.2950055.

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Film cooling performance is studied for cylindrical holes embedded in craters. Different crater geometries are considered for a typical crater depth. Cratered holes may occur when blades are coated with thermal barrier coating layers by masking the hole area during thermal barrier coating (TBC) spraying, resulting in a hole surrounded by a TBC layer. The film performance and behavior is expected to be different for the cratered holes compared to standard cylindrical holes. Detailed heat transfer coefficient and film effectiveness measurements are obtained simultaneously using a single test transient IR thermography technique. The study is performed at a single mainstream Reynolds number based on freestream velocity and film-hole diameter of 11,000 at four different coolant-to-mainstream blowing ratios of 0.5, 1.0, 1.5, and 2.0. The results show that film cooling effectiveness is slightly enhanced by cratering of holes, but a substantial increase in heat transfer enhancement negates the benefits of higher film effectiveness. Three different crater geometries are studied and compared to a base line flush cylindrical hole, a trenched hole, and a typical diffuser shaped hole. Computational fluid dynamics simulation using FLUENT was also performed to determine the jet-mainstream interactions associated with the experimental surface measurements.

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Lu, Yiping, Alok Dhungel, Srinath V. Ekkad, and Ronald S. Bunker. "Effect of Trench Width and Depth on Film Cooling From Cylindrical Holes Embedded in Trenches." Journal of Turbomachinery 131, no. 1 (September 25, 2008). http://dx.doi.org/10.1115/1.2950057.

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The present study is an experimental investigation of film cooling from cylindrical holes embedded in transverse trenches. Different trench depths are considered with two trench widths. Trench holes can occur when blades are coated with thermal barrier coating (TBC) layers. The film-hole performance and behavior will be different for the trench holes compared to standard cylindrical holes that are flush with the surface. The trench width and depth depend on the mask region and the thickness of the TBC layer. Detailed heat transfer coefficient and film effectiveness measurements are obtained simultaneously using a single test transient IR thermography technique. The study is performed at a single mainstream Reynolds number based on freestream velocity and film-hole diameter of 11,000 at four different coolant-to-mainstream blowing ratios of 0.5, 1.0, 1.5, and 2.0. The results show that film effectiveness is greatly enhanced by the trenching due to the improved two-dimensional nature of the film and lateral spreading. The detailed heat transfer coefficient and film effectiveness contours provide a clear understanding of the jet-mainstream interactions for different hole orientations. Computational fluid dynamics simulation using FLUENT was also performed to determine the jet-mainstream interactions to better understand the surface heat transfer coefficient and film effectiveness distributions.

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32

Bacci, Tommaso, Alessio Picchi, Tommaso Lenzi, Bruno Facchini, and Luca Innocenti. "Effect of Surface Roughness and Inlet Turbulence Intensity on a Turbine Nozzle Guide Vane External Heat Transfer: Experimental Investigation on a Literature Test Case." Journal of Turbomachinery 143, no. 4 (March 22, 2021). http://dx.doi.org/10.1115/1.4049917.

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Abstract Surface roughness is well known to significantly influence turbine aerodynamics and heat transfer; different studies have been undertaken in the last decades, in order to precisely characterize its effects and pursue a reliable and unified computational fluid dynamics modeling approach. Despite the effort, further research is still required to completely fulfill the goal, due to the complexity of the considered environment, with many other aspects and flow characteristics factoring into the final behavior. In this work, an experimental campaign was carried out to evaluate the heat transfer coefficient on a linear nozzle guide vane geometry. The adopted geometry has been developed and tested, at different inlet turbulence intensity, Reynolds and Mach number, at Von Kármán Institute. The results achieved on a test article with smooth surface were made available. In the present work, the effect of increased turbulence level and surface roughness was taken into account, respectively, using passive grids and conditioning the test sample surface finishing. Experiments were conducted using a transient technique by measuring the surface temperature evolution by IR thermography. The collected results integrate the existing database available in the open literature in order to support development and benchmarking of numerical approaches aimed at a reliable characterization of these aspects.

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Hossain, Mohammad A., Ali Ameri, James W. Gregory, and Jeffrey P. Bons. "Experimental Investigation of Innovative Cooling Schemes on an Additively Manufactured Engine Scale Turbine Nozzle Guide Vane." Journal of Turbomachinery 143, no. 5 (April 5, 2021). http://dx.doi.org/10.1115/1.4049618.

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Abstract This study includes the design, validation, and fabrication via direct metal laser sintering (DMLS) of a gas turbine nozzle guide vanes (NGV) that incorporates three innovative cooling schemes specifically enabled by additive manufacturing. The novel NGV design is the culmination of an extensive research and development effort over a period of 4 years that included low- and high-speed cascade testing coupled with unsteady computational fluid dynamics for numerous candidate innovative cooling architectures. The final vane design (SJ-vane) consists of sweeping jet (SJ) film cooling holes on the suction surface (SS), sweeping jet impingement holes at the leading edge and double-wall partial length triangular pin-fin with impinging jet at the trailing edge. For comparison purposes, a second DMLS enabled vane (777-vane) was designed and fabricated with prototypical cooling circuits to serve as a baseline. This vane consists of a shaped film cooling holes on the suction surface, circular impingement holes at the leading edge, and full-length cylindrical pin-fins at the trailing edge. Experiments with the two DMLS enabled vanes were performed at the Ohio State University Turbine Reacting Flow Rig (TuRFR) at engine-relevant temperature (1375 K) and Mach number conditions. Infrared (IR) thermography was utilized to measure the wall temperature of the pressure and suction surface at several coolant mass flowrates to estimate the overall cooling effectiveness (ϕ). Results showed improved cooling performance for the advanced cooling schemes (sweeping jet film cooling, impingement cooling, and triangular pin-fin cooling) compared with the baseline cooling schemes.

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34

Straußwald, Michael, Christopher Abram, Tobias Sander, Frank Beyrau, and Michael Pfitzner. "Time-resolved temperature and velocity field measurements in gas turbine film cooling flows with mainstream turbulence." Experiments in Fluids 62, no. 1 (December 17, 2020). http://dx.doi.org/10.1007/s00348-020-03087-2.

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Abstract Gas turbine film cooling strategies must provide adequate cooling performance under high levels of mainstream turbulence. Detailed information about the structure, dynamics and transport of the cooling films is needed to understand the flow physics and develop suitable numerical simulation tools. Here, we study film cooling flows in a wind tunnel with mainstream turbulence generated by an active turbulence grid. Gas temperature and velocity fields are measured using a laser-imaging method based on thermographic phosphor tracer particles. By replacing the previously used tracer BaMgAl10O17:Eu2+ with ZnO, significant gains in accuracy and precision could be achieved. The increased sensitivity (~ 1%/K) of ZnO led to a threefold improvement in the single-shot, single-pixel temperature precision to ± 5 K. The smaller particle size (dp,v ~ 600 nm) and agglomerated nanoparticle structure also reduced the tracing response time to ~ 5 µs allowing accurate tracking of turbulent fluctuations approaching 10 kHz. Moreover, no uncertainty arising from multiple scattering effects were observed using ZnO particles in this enclosed wind tunnel geometry at an estimated average seeding density of 2 × 1011 particles/m3. Time-average, fluctuation and single-shot temperature–velocity fields are presented for two mainstream turbulence levels ($$\overline{u}^{\prime}$$ u ¯ ′ /$${\overline{u}}_{\mathrm{m}}$$ u ¯ m = 7% and 14%) and two momentum ratios (IR = 4.7 and 9.3) at a fixed density ratio of 1.55. These flow conditions produce a cooling jet which is detached from the surface. High main flow turbulence causes faster mixing with the surrounding hot gas, increasing the wall-normal spreading of the cooling jet. The instantaneous flow fields show that mainstream turbulence has a significant effect on the shear layer velocity fluctuations and consequently on the streamwise and wall-normal turbulent heat flux, which is derived from the simultaneously acquired temperature–velocity data. We found that high mainstream turbulence reduces the heat flux away from the wall, suggesting that mainstream turbulence can act to diminish cooling performance. Sets of instantaneous measurements recorded at a 6 kHz repetition rate also reveal the dynamic interactions between the main flow turbulence and the cooling jet. These findings and the recorded data can be used to advance turbulence modelling for numerical simulations. Graphic abstract

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35

Chavez, Kyle, Thomas N. Slavens, and David Bogard. "Experimentally Measured Effects of Incidence Angle on the Adiabatic and Overall Effectiveness of a Fully Cooled Turbine Airfoil With Shaped Showerhead Holes." Journal of Turbomachinery 139, no. 9 (April 19, 2017). http://dx.doi.org/10.1115/1.4036200.

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Manufacturing and assembly variation can lead to shifts in the inlet flow incidence angles of a rotating turbine airfoil row. Understanding the sensitivity of the adiabatic film cooling effectiveness to a range of inlet conditions is necessary to verify the robustness of a cooling design. In order to investigate the effects of inlet flow incidence angles, adiabatic and overall effectiveness data were measured in a low speed linear cascade at 0 deg and 10 deg of the designed operating condition. Tests were completed at an inlet Reynolds number of Re = 120,000 and a turbulence intensity of Tu = 5% at the leading edge of the test article. Particle image velocimetry was used to verify the incident flow angle for each angle studied. The test section was first adjusted so that the pressure distribution and stagnation line of the airfoil matched those predicted by an aerodynamic computational fluid dynamics (CFD) model. IR thermography was then used to measure the adiabatic effectiveness levels of the fully cooled airfoil model with nine rows of shaped holes of varying construction and feed delivery. Measurements were taken over a range of blowing ratios and at a density ratio of DR = 1.23. This process was repeated for the two incidence angles measured, while the inlet pressure to the airfoil model was held constant for these incidence angle changes. Differences in laterally adiabatic effectiveness across the airfoil model were most evident in the showerhead, with changes as large as 0.2. The effect persisted most strongly at s/D = ±35 downstream of the stagnation row of holes, but was visible over the whole viewable area of 160 s/D. The effect was due to the stagnation line affecting the film at the showerhead row. Due to this effect, the showerhead was investigated in detail, including the effects of the stagnation line shift as well as the influence of the incidence angle on the overall effectiveness of the showerhead region. It was found that the stagnation line has the tendency to dramatically increase the near-hole adiabatic effectiveness levels when positioned within the breakout footprint of the hole. The effect persisted for the overall effectiveness study, since the hole spacing for this particular configuration was wide enough that the through hole convection was not completely dominant. This is the first study to present measured effectiveness values over both the pressure- and suction-side surfaces of a fully cooled airfoil for appreciably off-nominal incidence angles as well as examine adiabatic and overall effectiveness levels for a conical stagnation row of holes.

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Journal articles on the topic 'Dynamic IR thermography'

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