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Characterization of tracers for two-color laser-induced fluorescence liquid-phase temperature imaging in sprays
摘要： The variation of the fluorescence spectral signature of tracer solutions with temperature enables temperature imaging measurements in liquids and sprays by simultaneously recording and rationing the fluorescence intensity detected in two separate wavelength channels. In this work, we recorded fluorescence spectra of ethanol-based solutions of nine laser dyes used as tracers (PTP, stilbene 1, coumarin 152, coumarin 153, rhodamine B, rhodamine 101, pyrromethene 597, DCM, and pyridine 1) after excitation at either 266, 355, or 532 nm (depending on the dye) for temperatures between 298 and 348 K (close to the boiling point of the solvent), and for concentrations (depending on dye) around 10 mg/l (i.e., ~ 10–5 mol/l). The influence of signal self-absorption was investigated for the tracers best suited for thermometry, rhodamine B and coumarin 152, where the latter is almost unaffected due to its large Stokes shift. In thin-film (100 μm) cells, possible concentration effects on the fluorescence spectrum were investigated in the absence of signal self-absorption in the 0.1–10 and 0.5–50 mg/l range for rhodamine B and coumarin 152, respectively. Sensitivities of the two-color intensity ratios were determined for two selected color detection channels for each tracer characterized by their center wavelength and spectral half width and conditioned on averaged intensities of larger than 10% of the spectral peak of their respective fluorescence spectrum. The use of coumarin 152 that showed the overall best spectroscopic properties was demonstrated for temperature imaging in a burning ethanol spray.
关键词： coumarin 152,rhodamine B,sprays,temperature imaging,two-color laser-induced fluorescence,tracers
更新于2025-09-23 15:19:57
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Four-station laser tracer-based geometric error measurement of rotary table
摘要： The geometric errors of numerical control (NC) rotary tables can be measured using a single instrument according to the conventional measurement method. This study presents an efficient method for this measurement using four-station laser tracers. The three-dimensional coordinate measurement algorithm of the four-station laser tracer was established, the self-calibration of the laser tracer position and the spatial measuring point algorithm was realized, and the volumetric error of the measuring point on the rotary table was obtained. Then, the geometric errors of the NC rotary table were modeled using the screw theory, and a three-point measurement method was proposed to realize the separation of these geometric errors. Using the geometric error measurement experiment, six geometric errors of the NC rotary table were obtained. Compared with the conventional standard ball and laser interferometer measurement methods, the radial and axial runout results obtained using the laser tracer show differences of 0.08 and 0.07 μm, respectively, and the result of positioning error measurement shows a difference of 2.2 μrad. In addition, the method proposed in this study demonstrates an efficiency improved by five times, under the premise of ensuring the measurement accuracy, which broadens the possibilities for applications of rotation axes geometric error measurement in machining centers.
关键词： Four-station laser tracers,geometric error,rotary table,error separation
更新于2025-09-16 10:30:52
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Natural cooling of two axis tracking photovoltaic module
摘要： Recently, the solar energy is considered as one of the most essential alternative sources of energy, which make it significant to operate the photovoltaic (PV) modules at optimal points to attain maximum output powers at utmost efficiencies. In this work, a novel operational optimization scheme is proposed to maximize the electrical output power and its efficiency for two axis sun tracking PV module. The technique incorporates the influence of the surrounding environmental parameters; such as ambient temperature, wind speed, and wind direction to improve performance. The increase in power and efficiency is accomplished by benefiting from the local wind speed and wind direction to cool the cells temperatures, which in return assist the PV to operate at its Maximum Power Point Tracking (MPPT). These newly proposed operating angles (i.e., Azimuth and Tilt) for two axis sun tracking systems may not necessarily coincide with the perpendicular orientation used by conventional sun tracking PV modules. Finally, the effectiveness of the operational optimization technique and its effect on MPPT was verified using computer simulations using actual collected weather data that was obtained from Shams Maan weather station in Jordan.
关键词： PV cooling,solar optimization,Solar Tracking,PV improved efficiency,two axes tracers
更新于2025-09-12 10:27:22
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Oxygen Concentration Distribution Measurement of the Nozzle Flow Field by Toluene/Acetone Planar Laser-Induced Fluorescence
摘要： Planar laser-induced ?uorescence (PLIF) of toluene and acetone is performed for visualization of spatial distribution of oxygen in gas and oxygen mixing region in the nozzle ?ow ?eld. The principle of the calibration methods of oxygen concentration distribution is expounded in this paper. As the two tracers had different situations on oxygen quenching effect, the ratio of the ?uorescence images of the two tracers could be used to measure the oxygen concentration in the mixed area. In this way, the ratio of ?uorescence signal intensity of toluene to acetone was found to be linearly related to oxygen concentration. By using this calibration relationship, we can measure the oxygen concentration distribution of the nozzle ?ow ?eld with an accuracy of 12.6%. It indicates that this measurement method can be applied in a turbulent ?ow ?eld. The variation trend of oxygen concentration distribution in the nozzle ?ow ?eld can be analyzed by capturing multiple PLIF images in time sequence, which has the important reference value for the development of the nozzle burner ?ame.
关键词： nozzle ?ow ?eld,oxygen concentration distribution,?uorescence signal quenching,planar laser-induced ?uorescence,dual-tracers
更新于2025-09-11 14:15:04
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FluxTracer - A Ray Tracer Post-Processor to Assist in the Design and Optimization of Solar Concentrators and Receivers
摘要： This paper presents FluxTracer, an advanced open source computer tools to assist in the analysis, design and optimization of solar concentrators and receivers. FluxTracer is a post-processor for Monte Carlo ray tracers used to simulate the optical behavior of solar concentrating systems. By post-processing the rays generated by the ray tracer, FluxTracer can partition into volumetric pixels (voxels) a region of interest in three-dimensional space defined by the user and compute for each voxel the radiant power density of the concentrated solar radiation. Depending upon the set of rays provided by the ray tracer, it may be able to integrate the radiant power density in every voxel over time. The radiant energy density analysis described is just one of the analysis that FluxTracer can carry out on the set of rays generated by the ray tracer. This article presents the main analyses that FluxTracer can provide. It also presents examples of how the information provided by FluxTracer can be used to assist in the analysis, design and optimization of solar concentrators and receivers. FluxTracer is the first of a series of components of an open-source computational framework for the analysis, design and optimization of solar concentrators and receiver, being developed by The Cyprus Institute (CYI) and the Australian National University (ANU).
关键词： receivers,FluxTracer,solar concentrators,Monte Carlo ray tracers,open source,optimization
更新于2025-09-09 09:28:46