- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Evolution of volatile cloud in pulverized coal combustion with high-speed digital inline holographic visualization
摘要： The coal devolatilization plays a significant role in the combustion of pulverized coal particles. The evolution of volatile cloud during devolatilization of pulverized coal particles (105–125 μm) is studied in a high-temperature flat-flame burner by combining high-speed photography with high-speed digital inline holography (DIH). By the high-speed holographic visualization, the evolution of volatile cloud of pulverized coal from volatile release to soot aggregation generation can be divided into four stages. Effects of coal type on volatile cloud evolution are investigated using three different coals, i.e., Shanxi bituminous coal, Ximeng lignite and Yinni lignite. The results show that both the Shanxi bituminous coal and Ximeng lignite produce soot aggregation during devolatilization, which is rarely observed for Yinni lignite. Moreover, Shanxi bituminous coal has a higher potential in soot cluster formation for its higher coal rank than Ximeng lignite. The high-speed reconstructed image sequences are analyzed to measure the velocity slip between the parent particle and volatile cloud. Compared with Shanxi bituminous coal, Ximeng lignite exhibits a larger slip velocity. This work also demonstrates that high-speed DIH has the powerful capacity of directly observing the evolution of volatile cloud, and helps to gain a deep understanding of pulverized coal combustion.
关键词： Volatile cloud,Coal combustion,High-speed digital inline holography,Soot aggregation,High-speed photography
更新于2025-09-23 15:22:29
-
The distribution of OH in surface micro-discharge with different electrode widths by laser-induced fluorescence
摘要： Cold atmospheric plasma has been successfully applied in the field of biomedicine. One of the most pressing challenge is the development of plasma devices, for example, large-area application in wound healing. Surface micro-discharge device is one new type of dielectric barrier discharge design with desirable plasma features, such as homogeneity over a large surface area. In this study, two devices with electrode width varying from 0.25 to 1.00 mm were fabricated. The contribution focuses on the impact of the hexagonal mesh electrode width on the degree of uniformity of hydroxyl (OH) radicals in the downstream region and the OH transport efficiency. Accordingly, OH radicals were measured as an indicator by laser-induced fluorescence. Steady state measurements of OH perpendicular to the dielectric surface demonstrated that narrow electrode width could not offer a high degree of uniformity, and will reduce the transport efficiency of reactive species.
关键词： Plasma diagnostics - interferometry, spectroscopy and imaging,Plasma diagnostics - high speed photography
更新于2025-09-19 17:13:59
-
New infrared imaging diagnostic for the Neutral Beam Heating System at the TJ-II stellarator
摘要： An upgraded infrared imaging system has been installed at the stellarator TJ-II as a diagnostic tool of the Neutral Beam Injection heating. Thermographic analysis of the beam-wall interaction areas can be used to estimate the beam power lost through reionization and shine-through mechanisms in Neutral Beam heated plasmas. Three di?erent Regions of Interest inside TJ-II vacuum vessel have been determined whose thermographic analysis will be applied to the study of beam related processes. The optical conditions required for each application have been used to de?ne the speci?cations of the IR camera. Optimization of the optical design has been carried out by means of the optical simulation code ZEMAX. The IR window size has been increased to maximize the fraction of the ?eld of view that is free from vignetting. The system has been fully commissioned and is now operative, routinely providing thermographic data of the regions of interest during the last TJ-II experimental campaign. The IR diagnostic is described in detail and its applicability to study beam power deposition on di?erent targets is discussed.
关键词： Plasma diagnostics - high speed photography,Nuclear instruments and methods for hot plasma diagnostics,Beam Optics,Plasma diagnostics - interferometry, spectroscopy and imaging
更新于2025-09-12 10:27:22
-
Retardant Effects of Collapsing Dynamics of a Laser-Induced Cavitation Bubble Near a Solid Wall
摘要： In the present paper, the dynamic behavior of cavitation bubbles near a wall is experimentally investigated with a focus on the retardant effects of the wall on the collapsing dynamics of the bubble. In the present experiments, a cavitation bubble is generated by a focused laser beam with its behavior recorded through high-speed photography. During the data analysis, the influences of non-dimensional bubble–wall distance on the bubble collapsing dynamics are qualitatively and quantitatively investigated in terms of the interface evolution, the velocities of the poles, and the movement of the bubble centroid. Our results reveal that the presence of the wall could significantly affect the collapsing characteristics, leading to a dramatic difference between the moving velocities of interfaces near and away from the wall. With the decrease of the bubble–wall distance, the effects will be gradually strengthened with a rapid movement of the bubble centroid during the final collapse. Finally, a physical interpretation of the phenomenon is given based on the bubble theory, together with a rough estimation of the induced water hammer pressure by the bubble collapse.
关键词： solid wall,high-speed photography,retardant effect,cavitation,bubble collapse
更新于2025-09-11 14:15:04