Topic
Shadowgraphy
About: Shadowgraphy is a research topic. Over the lifetime, 555 publications have been published within this topic receiving 7204 citations.
Papers published on a yearly basis
Papers
Journal Article•
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TL;DR: In this paper, an assessment of the present knowledge in the following topics: (1) plasma torch and performance of blown arc (dc or ac), transferred arc and radio frequency torches; (2) established industrial applications with special emphasis on cutting, welding, spraying, transferred arc reclamation, reheating and purification, heating metal melts, smelting reduction, chemical operations, and waste destruction; (3) recent developments in the knowledge of fundamental processes in plasma torches with power sources, cathodes (hot and cold), anodes (static and dynamic behavior), and torch
Abstract: Although many thermal plasma processes have been developed for industrial applications, the wide acceptance as a manufacturing technology is prevented due to economical and competitive reasons, and/or reproducibility and reliability aspects. This paper is devoted to an assessment of the present knowledge in the following topics: (1) plasma torch and performance of blown arc (dc or ac), transferred arc and radio frequency torches; (2) established industrial applications with special emphasis on cutting, welding, spraying, transferred arc reclamation, reheating and purification, reheating metal melts, smelting reduction, chemical operations, and waste destruction; (3) recent developments in the knowledge of fundamental processes in plasma torches with power sources, cathodes (hot and cold), anodes (static and dynamic behavior), and torch components; (4) modeling-thermodynamic and transport properties, plasma flow with and without the Maxwell's equations; (5) measurement techniques including emission and absorption spectroscopy, laser scattering, enthalpy probes, video cameras, spectral analysis, shadowgraphy, and particle diagnostics either in flight with statistical measurements and those giving characteristics of a single particle upon flattening on a substrate; and (6) plasma-processing development in the presently used industrial processes and also in prospective processes with surface hardening, ultrafine powder production, plasma-assisted CVD, and plasma-fluidized or spouted bed reactors.
381 citations
TL;DR: In this paper, the authors investigated spatio-temporal evolution of ns laser ablation plumes at atmospheric pressure, a favored condition for laser-induced breakdown spectroscopy and laser-ablation inductively coupled plasma mass-spectrometry.
Abstract: We investigated spatio-temporal evolution of ns laser ablation plumes at atmospheric pressure, a favored condition for laser-induced breakdown spectroscopy and laser-ablation inductively coupled plasma mass-spectrometry. The 1064 nm, 6 ns pulses from a Nd:YAG laser were focused on to an Al target and the generated plasma was allowed to expand in 1 atm Ar. The hydrodynamic expansion features were studied using focused shadowgraphy and gated 2 ns self-emission visible imaging. Shadowgram images showed material ejection and generation of shock fronts. A secondary shock is observed behind the primary shock during the time window of 100-500 ns with instabilities near the laser cone angle. By comparing the self-emission images obtained using fast photography, it is concluded that the secondary shocks observed in the shadowgraphy were generated by fast moving target material. The plume front estimates using fast photography exhibited reasonable agreement with data obtained from shadowgraphy at early times ≤400 n...
210 citations
TL;DR: A detailed review of classical flow visualization methods can be found in this article, where Merzkirch and Lauterborn & Vogel present a beautiful collection of pictures by Van Dyke.
Abstract: Flow visualization results from the interaction between light and matter. Classical methods such as shadowgraphy, schlieren photography, and interferometry visualize variation in the index of refraction induced by changes in density, pressure, or temperature. Nonuniformities of these physical observables modify the phase of optical waves, rendered visible by free-space propagation (shadowgraphy), optical processing in the back focal plane of a lens (schlieren photography), or interference with a ref erence wave (interferometry). The classical methods visualize variations of the index of refraction or spatial derivatives thereof integrated along the light path through the fluid. Three-dimensional space is projected onto a plane with the corresponding reduction in degrees of freedom. Except for axial symmetric or two-dimensional flows, spatial structures cannot be recovered from a single image. Interior detail may be visualized by illuminating the flow with a sheet of light and imaging scattered radiation from variations in particle density or physical observables. Mie scattering is widely used because particles scatter more efficiently than molecules. Rayleighand Raman-scattering cross sections are small, necessitating intense laser sources for flow visu alization. Excellent reviews of classical flow-visualization methods have been pub lished, for example, by Merzkirch (1974) and Lauterborn & Vogel (1984) and a beautiful and inspiring collection of pictures by Van Dyke (1982).
207 citations
TL;DR: In this paper, spray formation and combustion characteristics of gasoline and E85 (85% ethanol, 15% gasoline) have been investigated using a multi-hole injector with asymmetric nozzle-hole arrangement.
200 citations
TL;DR: In this paper, a suitable analytical model to represent the decay of axial velocity from underexpanded sonic jets is presented. But the model is not suitable for fully expanded jets and the decay law proposed by Kleinstein, with suitable choice of parameters, gives a good representation when the exit diameter is modified by the exit pressure ratio.
Abstract: The work sets out to determine a suitable analytical model to represent the decay of axial velocity from underexpanded sonic jets. Experiments are carried out using shadowgraphy and laser Doppler anemometry to determine the near field jet structure and the axial velocity distribution for the complete field down to 30 mls over a range of exit nozzle diameters, exit pressure ratios and jet gases. Comparisons are made with existing data and the best models available for fully expanded jets. It is shown that the decay law proposed by Kleinstein, with suitable choice of parameters, gives a good representation when the exit diameter is modified by the exit pressure ratio.
180 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2026 | 1 |
| 2025 | 18 |
| 2024 | 13 |
| 2023 | 40 |
| 2022 | 82 |
| 2021 | 17 |