1996 Fiscal Year Final Research Report Summary
RAMAN SPECTROSCOPY FOR STRONG SHOCK WAVES IN AIR
| Project/Area Number |
05402052
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Aerospace engineering
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| Research Institution | CHIBA UNIVERSITY |
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Principal Investigator |
HONMA Hiroki CHIBA UNIVERSITY,GRADUATE SCHOOL OF SCIENCE AND ENGINEERING,PROFESSOR, 自然科学研究科, 教授 (90009233)
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| Co-Investigator(Kenkyū-buntansha) |
MAENO Kazuo CHIBA UNIVERSITY,FACULTY OF ENGINEERING,ASSOCIATE PROFESSOR, 工学部, 助教授 (30133606)
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| Project Period (FY) |
1993 – 1996
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| Keywords | SHOCK WAVE / NONEQUILIBRIUM RADIATION / HITH-TEMPERATURE AIR / RAMAN SPECTROSCOPY / HYPERSONIC FLOW |
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| Research Abstract |
The present research is associated with the shock-heating problem of space vehicles reentering into the earth's atmosphere. This project mainly aims to develop a technique of the Raman spectroscopy for nonequilibrium flows just behind strong shock waves, which are generated using a free-piston, double-diaphragm shock tube.
The results are summarized as follows.
(1) Performance study of the free-piston, double-diaphragm shock tube :
In order to syncronize the high-power laser pulse with the position of the shock front which moves at a hypersonic speed around 10 km/s, the precise reproduceability is requested for a shock speed to be fixed. The effects of the diaphragm-bursting time on the shock speed in the buffer chamber are clarified through experimental and computational studies. The reproduceability of the shock speed is remarkably improved by stabilizing each component of the apparatus.
(2) Imaging spectroscopy of the nonequilibrium shock front radiation :
The constructed system for radiation observation mainly consists of a streak camera and an I.I.CCD camera. It is the first system for obtaining time-resolved spectrographs of the nonequilibrium shock front radiation in air. Some new phenomena are found for two-dimensional profiles of total radiation and time-variations of specified spectra of the N_2^+ (-1) band.
(3) Study of Raman spectroscopy :
A system of Raman spectroscopy is developed using a high-power YAG laser, and some Raman signals are obtained for several high-density materials. The system was applied to shocked gas flows. However, the Raman signals have not been obtained yet for the shocked gas flows, using the present system. The increase of the laser intensity and/or the conversion to the CARS system are the preferable choice to the future study for extension.
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