Yoshiaki Miyazato

Optical Measurements of Shock Wave Oscillations in Transonic Diffusers by High-Speed Mach-Zehnder Interferometers

The two dimensional unsteady structure including the interaction between a normal shock wave and turbulent boundary layer in a transonic diffuser is quantitatively and qualitatively visualized using high-speed Mach-Zehnder interferometry. Experiments have been performed at an operating pressure ratio of 1.4 where the freestream Mach number just ahead of the normal shock wave is around 1.1. The normal shock oscillatory characteristics in the diffuser are also investigated by a high-speed schlieren method. Streamwise static pressures on the diffuser side wall have been measured and the time-mean wall pressure distribution in the diffuser is compared with that from the RANS equation with the k- SST turbulent model. The dominant frequency of the normal shock oscillation obtained from the Mach-Zehnder interferometry is quantitatively identical to that from the high-speed schlieren mothod.

Quantitative Flow Visualization of Correctly Expanded Supersonic Jets by Rainbow Schlieren Deflectometry

A quantitative visual study of a correctly-expanded supersonic jet of a Mach number of 1.6 by the rainbow schlieren deflectometry has been conducted to reveal the jet flow field quantitatively. Rainbow schlieren images of the jet have been taken by a schlieren system with a rainbow filter which has a continuous hue distribution. The density contour plot of the jet flow is determined by using the image analysis based on the Abel inversion of experimental data of transverse displacement at the cut-off plane. Also, Pitot probe measurements at a jet cross-section have been carried out to obtain density profiles. The radial distribution of the density from the schlieren quantitatively agrees well with that from the Pitot probe.

Investigations of Underexpanded Moist Air Sonic Jets from Axisymmetric Convergent Nozzles

The structure of the moist air sonic jet issued from axisymmetric convergent nozzles has been experimentally investigated. Static pressures along the nozzle axis for a range of relative humidity from  = 0.35 to 0.98 have been measured by the through-tube system installed in the indraft supersonic wind tunnel. Also, the Reynolds averaged Navier-Stokes equation with the Menters k-SST model for dry air sonic jets ( = 0) has been numerically solved. Effects of the relative humidity on the centerline static pressures in the moist air sonic jets are clarified.

Measurements in Overexpanded Supersonic Jets by Rainbow Schlieren Deflectometry

A visual study of an overexpanded supersonic jet issuing from an axisymmetric convergent-divergent nozzle by the rainbow schlieren deflectometry technique has been conducted to reveal the shock containing jet flow field quantitatively. Rainbow schlieren images of the jet have been taken by a schlieren system with a rainbow filter which has a continuous hue distribution. The density contour plot of the jet flow is determined by using the image analysis based on the Abel inversion of experimental data of transverse displacement at the cut-off plane. Leading and rear shocks as well as a Mach disk in the jet flow are clearly visible in the density contour plot of the jet. Also, the density ratio across the Mach disk obtained from the experiment shows an excellent agreement with the theoretical value across a normal shock wave quantitatively.