The mixing processes in supersonic flows are visualized by the Schlieren method. A gaseous nitrogen jet is injected normally into the external flow through a traverse slot nozzle mounted on the flat plate model. Experiments are conducted under the conditions of freestream Mach number of 3.81, total pressure of 1.2 MPa, Reynolds number of 1.0×10⁷. Sonic nozzles, whose width are 0.5, 1.0 and 2.0 mm, are used. In the experiments the total pressure ratio of the secondary flow to the freestream is varied from 0.1 to 0.5.
The results show that the bow shock wave/turbulent boundary layer interaction induces the boundary layer separation in front of the injection. In the interacting flow, barrel shock waves and Mach disk are observed clearly. As the total preesure ratio is increased, the separation region, the extent of the interaction region and shock structures becomes larger.

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The unsteady flow fields around an oscillating airfoil are visualized by a smoke wire method in order to investigate the detailed flow structure and the mechanism of the dynamic stall.
In the experiments a wing section of NACA0012, whose span is 1250 mm and chord is 250 mm, is used. The wing section is set in a low speed wind tunnel, whose diameter is 2 m. and a couple of wide side plates are prepared to keep the two-dimensionality in the test section. The experiments are carried out under the testing conditions of freestream velocity of 4 m/s and Reynolds number of 7.2×10⁴. The wing section is oscillated sinusoidary around 25% chord from the leading edge at reduced frequency of 0.2 with an amplitude of 4 degrees around mean attack angles of 14, 16 and 18 degrees.
The significant changes of the extent of separated region behind a wing section at increasing and decreasing process of the attack angle is observed. The results suggest the characteristics of dynamic stall are well captured in the experiments. Also flow patterns are compared with numerical results which are conducted at the same conditions. At attack angle of 14 degrees both results show good agreements.

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Turbulence structures have been studied in the fully-developed turbulent flow through a pipe with a square cross section using velocity measurement together with flow visualization. Ejection and sweep, observed in a wall turbulent flow, were confirmed in the wall region except for the vicinity of corners. The relation between these structures and velocity fluctuations was investigated in view of the profiles of probability density functions. As a result, it was shown that ejection and sweep contribute to the skewness factors of velocity fluctuations. In addition, valuable information about the conditional sampling of these structures was obtained.

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