In order to reveal the unsteady structure of secondary flow of a turbulent bounded jet in both frequency and physical spaces, the wavelet cross spectrum was used to analyze the experimental velocity signals at two different positions near the wall in the near field. From the wavelet cross spectrum between two different fluctuating velocity components, the instantaneous contribution to Reynolds stress and the mechanism of eddy motion and secondary flow may be easily analyzed. The wavelet cross spectrum analysis of the velocity components at two different locations may determine the frequency and the location of the large-scale structure and the secondary flows in the shear layer near the wall.

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The time and spatial temperature profiles on the impingement plate were measured by using an infrared radiometer with a two-dimensional array of Indium-Antimony (In Sb) sensors for various nozzle exit-to-plate separations, when the jet being issued from an elliptic nozzle impinges to the target plate. The isotherms of infrared images, as well as the heat transfer coefficients were obtained. The heat transfer coefficients were also measured by using of thermocouples. The flows on the plate were visualized by the oil-film method to compare the isotherms or the heat transfer contours. Furthermore, the velocity and the turbulence intensity were measured by a hot wire anemometer. It was found that the phenomena of axes switching, which is caused by the differences in the selfinduced velocity in the non-circular vortices, was observed and the heat transfer characteristics well corresponds to the flow patterns.

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Thermo-sensitve liquid crystal display thermal distribution as it changes color according to temperature. By using the developed color image processing technique, spatial thermal information can be obtained. However, modification of the relation between color and temperature is necessary, because the color also depends on an observation angle. The modification is made possible by observing color distribution in the constant temperature field. Liquid crystal is in general inappropriate for measuring a wide thermal range, because its thermo-sensitive range is relatively narrow. Authors expanded this approach to measurement of a wider temperature range using two mixed ratios of liquid crystal with different thermo-sensitive ranges. Applying this approach, thermal plume in a natural convection field is successfully examined.

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This paper presents a flow visualization study of swept shock wave / turbulent boundary layer interactions using computer image processing technique in the supersonic flow at Mach number of 3.1. The test model is composed of a flat plate and sharp fins. Images obtained from oil-spot, liquid crystal coatings for surface shear force and vapor screen visualization were processed. Streaklines of oil spots are determined quantitatively by an active threshold selection method. By image processes of liquid crystal coatings for surface shear force and vapor screen, the spatial relation among shear stress distribution, separation lines and separation vortex is clarified. Surface pressure distribution is integrated into these processed images for comparison.

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Numerical studies on pulsating jets in a free shear, layer are carried out in order to estimate the effects of pulsating frequencies, amplitude ratio and Reynolds numbers on the behaviour of eddies formed in a free shear layer. The numerical results show good agreement with experimental data that are obtained in the previous report. Some characteristic scales of eddies formed in a free shear layer are expressed as empirical functions of each parameters. The outer scales of eddies are expressed as a sum of effects of basic expansion of eddy widths, integrated inflow and accelerations of flow. The reduced flow widths of jets are expressed as a sum of effects of simple reduction rate of eddy widths and inlet velocity change with time. The effect of each factor on characteristic scales is discussed quantitatively.

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A mechanism of the discrete frequency noises generated from symmetrical airfoils was investigated in transition Reynolds numbers. The following results are obtained. When the discrete frequency "noise generates, the boundary layer separates from the airfoil surface upstream of the trailing edge and the rolling-up position of wake vortices is just after the dead air region. When the boundary layer flow attached up to the trailing edge, the rolling-up position of wake vortices is far from the trailing edge. Then the shear flow does not fluctuate at the trailing edge and the discrete frequency noise little generates. That is, the formation of wake vortices does not always generate the discrete frequency noise and the rolling-up position of the wake vortices is closely related to the generation of discrete frequency noises in transition Reynolds numbers.

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