Power performance of an offshore floating photovoltaic undergoing motions: Effects of dynamic incidence angle and partial shelter

The blade leading edge is directly exposed to hot gas, and its cooling performance is highly sensitive to the mainstream incidence angle. This study numerically investigates the effects of the mainstream incidence angle on the film cooling effectiveness of the blade leading edge. It compares the cooling performance of cylindrical and laidback holes at varying mainstream incidence angles of -2° , 0° , and +2° under blowing ratios of 0.75, 1.5, and 2.25. Film cooling effectiveness for both types of holes increases with the increasing incidence angle under blowing ratios of 0.75 and 1.5, while the opposite occurs under the blowing ratio of 2.25. This is due to the fact that the effect of the incidence angle on the mixing of coolant and mainstream varies with the blowing ratios. The area-averaged film cooling effectiveness for laidback holes remains at least 26% higher than that for cylindrical holes at varying incidence angle under each blowing ratio. Moreover, the cooling performance stability of laidback holes is better than that of cylindrical holes when the mainstream incidence angle changes from design to off-design conditions.

Effect of incidence angle on PV soiling loss

Molecular dynamics simulation of structural changes of lipid bilayers induced by shock waves: Effects of incident angles

The rotation fluctuation or the mainstream unsteadiness could cause the variation of the incoming incidence angle, affecting the cooling performance of the turbine blade. Most literature concentrates on the effects of incidence angle in the mid-pitch region, leaving the tip region less concerned. Considering that the complicated flow field in the tip region could sometimes worsen cooling effectiveness, this paper investigates the effects of mainstream incidence angle on the cooling performance of the rotational blade tip. The first stage of GE-E3 high pressure turbine blade with full composite cooling structure is used in this study and conjugate heat transfer numerical simulations are conducted on ANSYS CFX 2019R3 to calculate both the flow field and the solid temperature field. SST k-w turbulence model is adopted to enclose the RANS methods after multiple validations. Three rotational speeds, namely, 90%, 100% and 110% of the design point (13287 rpm), are simulated in three coolant mass flow rates (1.65%, 3.3% and 4.95% of the main flow rate) and three tip clearance ratios (0.5%, 1% and 1.5% of the total blade pitch). According to the results, the pressure side rim consistently gets cooler as the incidence angle changes from positive to negative because less leakage gets over the pressure rim. But in comparison, the trends of the suction side are complex. At the positive incidence angle, the large pressure difference forces nearly all coolant to exhaust over the suction rim, facilitating the coolant coverage there. At zero incidence angle, the leakage over the suction rim could raise the temperature in the thickest area. But as the incidence angle turns negative, the larger mainstream leakage over the suction rim could form an anti-rotating vortex. With large coolant flow rate or small tip clearance, the mainstream invasion would increase the temperature whereas with small coolant flow rate or large tip clearance, the vortex entrainment could decrease the temperature.

A detailed study on the effects of sunshape and incident angle on the optical performance of parabolic trough solar collectors

In this article, a new ultrafast laser polishing method for SiC/SiC composites was reported and the effects of different incident angles were discussed in detail. The results indicated that the incident angle had a great influence on the polishing of SiC/SiC composites. Under the normal incident condition, the surface roughness was barely improved and the laser-induced defects even degraded the process quality. With the increasing incident angle, surface oxidation and defects dramatically decreased. At 80 degrees, the surface convex structure is almost eliminated and the protruding fiber was neatly cut off. Furthermore, a theoretical model of laser polishing for SiC/SiC composites is used to analyze the laser propagation and power density distribution in different incident angles. The model successfully predicted the laser energy resonance enhancement and illustrated the formation mechanism of laser-induced defects and nanoripples. Meanwhile, the result shows that the laser energy concentrated on the convex fiber of composites as the incident angle increased, which explained that the SiC/SiC composites polishing quality was significantly improved under the inclined incident condition.

The intensity information from terrestrial laser scanners (TLS) has become an important object of study in recent years, and there are an increasing number of applications that would benefit from the addition of calibrated intensity data to the topographic information. In this paper, we study the range and incidence angle effects on the intensity measurements and search for practical correction methods for different TLS instruments and targets. We find that the range (distance) effect is strongly dominated by instrumental factors, whereas the incidence angle effect is mainly caused by the target surface properties. Correction for both effects is possible, but more studies are needed for physical interpretation and more efficient use of intensity data for target characterization.

This study assesses the use of multibeam RADARSAT-2 multipolarized synthetic aperture radar images (hereafter termed “RADARSAT-2 images”), in combination with LANDSAT-7 Enhanced Thematic Mapper (ETM +) and digital elevation model (DEM) data for mapping surficial materials (bedrock, boulders, organic material, sand and gravel, thick till, and thin till) in Arctic Canada. In particular we tested the effects of RADARSAT-2 incidence angles on classification accuracy. This research contributes to the geoscience framework for mineral exploration in Archean to Paleoproterozoic rocks of the northeast Thelon region of Nunavut. The RADARSAT-2 images were acquired in three west-looking descending beam modes (FQ1, FQ12, and FQ20) with increasing respective incidence angles. A maximum likelihood classification (MLC) was applied to different combinations of RADARSAT-2 and LANDSAT-7 ETM+ images, and DEM data. The incidence angle effect on classification overall accuracies is greatest when only the HH polarized images are used, but is reduced when the HV and (or) VV polarized images are added to the classifier. The best MLC overall accuracy of 85.1% is achieved by combining all polarizations and all incidence angles (beam modes) with LANDSAT-7 ETM+ images and DEM data. The influences of variable environmental conditions (moisture and temperature) on mapping accuracy require further research.

Effects of incidence angle and optimization in femtosecond laser polishing of C/SiC composites

The effect of the laser ray incidence angle on the mass ablation rate and ablation pressure of planar inertial confinement fusion (ICF) targets is explored. In this work, a modified version of the textbook model of laser ablation [Manheimer et al., Phys. Fluids 25, 1644 (1982)] is used to demonstrate that the mass ablation rate and ablation pressure scale with the 4/3 and 2/3 power of the cosine of the laser ray incidence angle relative to the target normal. Using an idealized planar model of ablation, it is demonstrated that constant irradiance is insufficient to produce similar velocities of a target when comparing cases driven at different incidence angles. Additionally, the effect of the incidence angle on the absorption fraction is demonstrated and it is shown that a longer duration is needed to achieve maximum absorption for greater angles. This further affects the mass ablation rate and ablation pressure in the first nanosecond of ablation. These results, when extrapolated, may provide insight into the variation of drive conditions encountered due to incidence in polar direct drive ICF.

This study investigated the erosive wear of a polyurea coating with a hardness of 95 ShA and a thickness of 3 mm applied to a 3 mm thick plate made of S235 steel. The process of erosive wear was carried out using a stream of compressed air containing abrasive grains of aluminum oxide (Al2O3). The erosive wear was studied using different incidence angles (45°, 60° and 90°) and erosive grain sizes. Thus, the effects of the incidence angle and erosive grain size on the erosive wear of the polyurea coating were analyzed. Erosive wear was determined as linear wear: the depth of the wear trace was measured using an optical profilometer. This study showed a non-linear correlation between erosive wear, incidence angle and erosive particle size. In addition, a qualitative study of the surface of the coating after a wear test was carried out using a scanning electron microscope, which made it possible to describe the mechanisms of erosive wear of the polyurea coating.

In an earlier investigation [Sivonen and Ellermeier, J. Acoust. Soc. Am. 119, 2965-2980 (2006)], the effect of sound incidence angle on loudness was investigated for anechoic, narrowband sounds. In the present follow-up investigation, the effect of incidence angle on loudness was investigated using wideband sounds under anechoic conditions and narrowband sounds under reverberant conditions. Five listeners matched the loudness of a sound coming from five incidence angles in the horizontal plane to that of the same sound with frontal incidence. These directional loudness matches were obtained with an adaptive, two-alternative, two-interval, forced-choice procedure. The stimuli were presented to the listeners via individual binaural synthesis. The results show that loudness depends on sound incidence angle in both experiments. The wideband and reverberant sounds, however, yielded significantly smaller directional effects than had been obtained for the same listeners when anechoic, narrowband sounds were used. When modeling the binaural summation underlying the loudness matches, a power summation of the at-ear signals yielded good predictions for all types of stimuli investigated.

The CosmoQuest virtual community science platform facilitates the creation and implementation of astronomical research projects performed by citizen scientists. One such project, called Moon Mappers, aids in determining the feasibility of producing crowd-sourced cratering statistics of the surface of the Moon. Lunar crater population statistics are an important metric used to understand the formation and evolutionary history of lunar surface features, to estimate relative and absolute model ages of regions on the Moon's surface, and to establish chronologies for other planetary surfaces via extrapolation from the lunar record. It has been suggested and shown that solar incidence angle has an effect on the identification of craters, particularly at meter scales. We have used high-resolution image data taken by the Lunar Reconnaissance Orbiter's Narrow-Angle Camera of the Apollo 15 landing site over a range of solar incidence angles and have compiled catalogs of crater identifications obtained by minimally trained members of the general public participating in CosmoQuest's Moon Mappers project. We have studied the effects of solar incidence angle spanning from approximately 27.5 deg to approximately 83 deg (extending the incidence angle range examined in previous works), down to a minimum crater size of 10 m, and find that the solar incidence angle has a significant effect on the crater identification process, as has been determined by subject matter experts in other studies. The results of this analysis not only highlight the ability to use crowd-sourced data in reproducing and validating scientific analyses but also indicate the potential to perform original research.

The incidence angle of a detonation wave in a conventional high explosive influences the acceleration and terminal velocity of a metal flyer by increasing the magnitude of the material velocity imparted by the transmitted shock wave as the detonation is tilted towards normal loading. For non-ideal explosives heavily loaded with inert additives, the detonation velocity is typically subsonic relative to the flyer sound speed, leading to shockless accelerations when the detonation is grazing. Further, in a grazing detonation the particles are initially accelerated in the direction of the detonation and only gain velocity normal to the initial orientation of the flyer at later times due to aerodynamic drag as the detonation products expand. If the detonation wave in a non-ideal explosive instead strikes the flyer at normal incidence, a shock is transmitted into the flyer and the first interaction between the particle additives and the flyer occurs due to the imparted material velocity from the passage of the detonation wave. Consequently, the effect of incidence angle and additive properties may play a more prominent role in the flyer acceleration. In the present study we experimentally compared normal detonation loadings to grazing loadings using a 3-mm-thick aluminum slapper to impact-initiate a planar detonation wave in non-ideal explosive-particle admixtures, which subsequently accelerated a second 6.4-mm-thick flyer. Flyer acceleration was measured with heterodyne laser velocimetry (PDV). The explosive mixtures considered were packed beds of glass or steel particles of varying sizes saturated with sensitized nitromethane, and gelled nitromethane mixed with glass microballoons. Results showed that the primary parameter controlling changes in flyer velocity was the presence of a transmitted shock, with additive density and particle size playing only secondary roles. These results are similar to the grazing detonation experiments, however under normal loading the largest, higher density particles yielded the highest terminal flyer velocity, whereas in the grazing experiments the larger, low density particles yielded the highest terminal velocity.

Investigation of effects of swift heavy ion irradiation on few-layer graphene: A molecular dynamics simulation study