A Study on the Unsteady Vortex Structure of a Jet and its Mixing Process by Laser Induced Fluorescence Method

Research Project

Project/Area Number	62460099
Research Category	Grant-in-Aid for General Scientific Research (B)
Allocation Type	Single-year Grants
Research Field	Thermal engineering
Research Institution	Nagoya Institute of Technology
Principal Investigator	YAMAGUCHI Shigeki Nagoya Institute of Technology, Professor, 工学部, 教授 (70023025)
Co-Investigator(Kenkyū-buntansha)	HASEGAWA Tatsuya Nagoya Institute of Technology, Associate Professor, 工学部, 助教授 (40164818) OHIWA Norio Nagoya Institute of Technology, Associate Professor, 工学部, 助教授 (00023341)
Project Period (FY)	1987 – 1988
Project Status	Completed (Fiscal Year 1988)
Budget Amount *help	¥5,400,000 (Direct Cost: ¥5,400,000) Fiscal Year 1988: ¥700,000 (Direct Cost: ¥700,000) Fiscal Year 1987: ¥4,700,000 (Direct Cost: ¥4,700,000)
Keywords	Laser Induced Fluorescence / Jet / Vortex Structure / 物質輸送 / レーザ励起蛍光法
Research Abstract	Jet flow apparatus and measurement system were developed in 1987, and the following results were obtained using the experimental system in 1988: 1. The laser induced fluorescence signal of iodine molecules did not depend on the jet velocity. Thus, the iodine concentration can be measured without considering the effect of velocity. 2. Heterogeneous distribution of the laser light intensity can be corrected by the distribution of the laser light intensity can be corrected by the distribution of the fluorescence signal in a static cell homogeneously including iodine molecules. 3. Two-dimensional measurements were performed after establishing the experimental procedures: (1) Two-dimensional average iodine concentration in a nitrogen jet with a velocity of 19 m/s was measured at an exposure time of 250 ms. The two-dimensional image of the iodine concentration showed the development of the jet and the selfsimilar profiles of iodine distribution. (2) An unsteady injected helium jet in a cell containing helium diluted iodine was visualized at a rate of 100 frames/s. The jet collapsed with tha wall and a pari of vortices appeared. Mixing of the jet with the gas in the cell occurred in the vortices. The limit of the exposure time of our measurement system was found out to be 10 ms, mainly due to the weak intensity of the laser light (1W). (3) A vortex ring which appeared at the initiation of a jet was visualized at a rate of 100 frames/s. The sequential images showed that the gases was mixed by the vortex ring.