| Budget Amount *help |
¥3,860,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥360,000)
Fiscal Year 2007: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2006: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
Laser-induced fluorescence (LIF) offers a powerful diagnostic technique for the measurement of supersonic and transonic flows. Several combinations of lasers and tracer materials have been known. Nitric oxide emits fluorescence when irradiated by ultraviolet light obtained by a dye laser. Nitric oxide, however, is toxic and, in addition, it is an active molecule and reacts with oxygen. Oxygen emits LIF by an ArF excimer laser. This can avoid the problems of nitric oxide, but the fluorescence yield is usually very. Iodine excited by an argon ion laser provides another LIF diagnostic method. The fluorescence yield of this is much larger than the above two, but the application to the flow field is limited by the corrosive nature of iodine.
In recent years, the acetone LIF method has attracted considerable attention. Acetone is non-corrosive, weak toxic and emits strong LIF. The acetone LIF method is promising as a quantitative diagnostic tool for the measurement of compressible flows. However, it has not been verified that this method can measure compressible flows because fluorescence characteristics of acetone under low temperature conditions are not well understood. In this research, the study is done to check the possibility of this method as a diagnostic tool to measure the number density in supersonic flows where temperature is lower than the atmosphere. Low temperature condition is made by underexpanded supersonic jets emanating from nozzles. The LIF intensity in the jets is measured by the CCD camera and compared with the theoretical intensity calculated by extending the multi-step decay model of Thurber, et al. to a low temperature regime. This comparison makes it possible to check the validity of the extended model. Using this checked model, we estimate the sensitivity of the LIF-measured number density to change in temperature, and examine the accuracy in measurement.
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