Observation of Atomization Process of Spray by High Sensitivity Photography
Speckle noise was removed by SK-11(left). Speckle noise is generated and image quality is deteriorated(right).
The two images above are the photographs of atomization process of water spray nozzle. The left one is taken when laser speckle noise was removed by SK-11, the right one is without SK-11. The water spray is generated by a hollow-cone type nozzle (Delavan 0.85-60°A) at the injection pressure of 1.6MPa. The photos record the moment of the water spray atomization by using a YAG pulsed laser (3mm in beam diameter and about 10mJ outputs) to radiate a laser beam and scatter it by a diffuser to illuminate the spray process. It is understood that the speckle noise is reduced and the image quality is improved by using SK-11.
The data was provided by courtesy of:
Associate prof. Takashi Suzuki of Toyohashi University of Technology;
Central Research Institute of Electric Power Industry.
The water spray atomization process (SK-11 is used). The two images compared above are the enlarged photos of the red frame.
A setup schematic of this measurement.
Observation of atomization and speckle noise
The atomization technology of liquid is applied to various industries, such as atomization of the fuel spray in an automobile engine, spray painting, and spray drying, humidity conditioning, powder manufacturing, agricultural chemicals spraying and fire extinction. Especially, the applications to the washing of various kinds of environmental equipment and the temperature limiting of incinerator, desulfurization and denitration technologies, etc are remarkable. And high controls of the atomizing property have come to be demanded for the equipment in recent years.
For instance, if the atomizing property is improved, the reduction of pollutants in the vehicle exhaust emission and the increase in thermal efficiency in the engines are also expected. Therefore, the study on spray formation process in a fuel injection nozzle and the measurement of the atomization characteristics are needed.
For taking the photograph of spray formation process, xenon flash lamp or YAG pulsed laser for a higher resolution is used. However, laser speckle noise is generated because of the highness of monochromaticity, and the image is deteriorated when using the YAG pulsed laser.
To remove this speckle noise and to analyze the spray formation process in detail, the speckle reducer SK-11 of Nanophoton demonstrates high performance.
Photos taken with xenon flash lamp(Δτ～1μs)(up) and YAG pulsed laser(down) respectively. Though higher accuracy of the atomization process can be observed when using YAG pulsed laser, speckle noise is generated in the whole image.
