This paper describes the application of discrete wavelet transform to the analysis of condensation jets in order to clarify the fluid and heat transfer phenomenon. The condensation jets in nozzle vicinity are experimentally visualized with laser light sheet method to obtain the condensation particle density images of the jets. The image of the condensation particle density in the jet is decomposed to the mean value and the fluctuation value images by means of wavelet multiresolutoin. The dominant temperature boundary and the mean component outside boundary were provided from wavelet separation images. These boundaries were compared with the temperature distribution provided from the experimental result.

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The relation between pressure fluctuation inside a rectangular cavity and flow structure around the cavity was investigated experimentally. The cavity was installed in supersonic internal flow at Mach numbers 1.83 and 2.13. The length of the cavities was varied from 10 to 40 mm, whereas the depth was kept at 20 mm. In order to observe the flow structure around the cavity, three kind of methods; schlieren method, tracer method and oil flow method were applied. The pressure fluctuation inside the cavity was measured by using pressure transducers. It was found that the amplitude of the pressure fluctuation was large when the flow structure inside the cavity was unstable, and the amplitude was small when the flow structure was stable. It means that the amplitude of the pressure fluctuations is much influenced by the flow structure inside the cavity.

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