The flow structures of the circular jet issuing from a pipe with the fluttering fins were experimentally investigated by the flow visualization of the LIF method and the PIV analysis. Especially, the effects of the fin length on the flow structures were studied. As a result, it is evident that the large-scale structures were broken into smaller-scale ones and the jet diffusion was enhanced in using the short fluttering fins, such as L/d=1.5. However, the long fluttering fins, such as L/d=2.5, caused the strong fluctuation of jet. Therefore, it may say that there exists a suitable fin length L/d=1.5, producing the strongest jet diffusion.

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In the present study, we adopt a rod lighting system to the focusing schlieren system to obtain the higher and more uniform bright lighting at the test section. And flow visualization around a double wedge airfoil was performed in the transonic shock tube flow by using the focusing schlieren system. The span, chord length and maximum thickness of the model are 60mm, 75mm and 7.5mm, respectively. The hot gas Mach numbers (test Mach numbers) are from 0.80 to 0.86, and the Reynolds numbers are from 4.0x10^5 to 4.6x10^5. The test results show that an increment of light intensity was obtained by the experiments of the rod extended light source, and relatively constant light intensity was achieved at the test plane surface, and that, on the shock tube airfoil testing at the angle of attack 0 deg., if the Mach number is increased, the shock wave on the airfoil model moves to further downstream. This latter result is nearly the same as aerodynamic characteristics of NACA0012 airfoil model.

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