High-Speed Visualization of Nanopowder Combustion in Air

Abstract

The paper discusses the methods of high-speed imaging of high-temperature processes in a real time mode: passive registration in the own light, usage of laser illumination, and using the laser monitor. The visualization results of combustion in air of Al nanopowder and thermite Al-Fe2O3 mixture are presented. The perspectives of application of laser monitors in NDE are considered, particularly for the study of laser ignition of thermite mixtures and solid fuels.

Laser Systems for Distant Monitoring of Nanopowder Combustion

“…The second scheme of high-speed imaging used in this work was the scheme with laser illumination. We used the scheme with laser illumination early with 532 nm wavelength and 5 mW power continuous DPSS laser in [11]. It was shown that the method of visualization with external laser illumination is good for panoramic view of the processes.…”

“…Particularly, aluminum-based materials obtained by high-temperature combustion of nanopowders in air offer a number of interesting and potentially high impact commercial opportunities [1][2][3][4][5][6][7][8][9]. Combustion of aluminum and iron nanopowders and their mixtures proceeds at temperatures above 2000 • C and is accompanied by a bright gloving and the scattering of combustion products in some cases [10,11]. Moreover, the combustion of nanopowders is a fast process with a flow rate of a few millimeters or centimeters per second.…”

“…Opportunities for observing high-temperature high-speed processes, in particular, nanopowder combustion processes, appear with the use of laser radiation and high-speed video recording [10][11][12][13][14][15][16][17]. When an observation object is illuminated by narrow-band laser radiation, a part of the radiation is reflected from the surface.…”

“…When an observation object is illuminated by narrow-band laser radiation, a part of the radiation is reflected from the surface. If the intensity of the reflected radiation is higher than the intensity of the flame, it can be filtered and recorded by the camera [11]. If the intensity of the reflected radiation is comparable to the radiation of the flame, it should be amplified in brightness, and then recorded.…”

“…These imaging systems allow observation through the flame or plasma and visualization of the processes shielded by intensive background lighting. In particular, they can be used to perform diagnosis of the substance surface burning with high intensity of light emission during the combustion or plasma induced processes [10][11][12][27][28][29][30]. For the first time, an active optical system with brightness amplification was used to study the aluminum nanopowder combustion in [12].…”