Shigetoshi Kawagoe

Numerical Study of Entry Waves Produced by High-Speed Trains Entering a Tunnel. Effects of Nose Shape of Train.

In this study, entry waves produced by high-speed trains which enter a tunnel were numerically investigated. The equations of the one-dimensional, unsteady and compressible flow with mass removal in which the area of a tunnel is dependent on the time and distance were numerically solved by the method of characteristics. The calculations were performed for trains with various nose shapes in the case in which the speed of the train was 300km/h, and the effects of the nose shape of the train on the entry waves were quantitatively clarified. As a result, the optimum condition of the nose shape which forms the entry wave with minimum pressure gradient was shown.

Numerical Study of Shock Waves Propagating in an Elbow. Effects of Elbow Angle.

In this paper, the shock wave propagating in an elbow and the transient flow induced by the shock were investigated numerically in order to clarify how the shock wave transmitted past the elbow is stabilized to uniformity by the effects of the elbow angle. Computations were carried out by solving the two-dimensional compressible Navier-Stokes equations using the total variation diminishing (TVD) scheme. Calculations were performed for six elbow angles between 5° to 120°, and the flow fields were numerically visualized by the contour lines of pressure, sonic lines, pressure distributions and wave diagrams. The numerical results showed that the distance for which the nonuniformity of the transmitted shock continued became longer with increasing elbow angle and the attenuation of the transmitted shock was very small.

Analytical Study on Post-Shock Expansion in Transonic Flow

A simple analytical method for the interaction between weak normal shock waves and turbulent boundary layers on flat surfaces is presented. The flow is assumed to be adiabatic, two-dimensional and to follow the power-law form. An empirical relation for a normal shock wave in transonic flow is taken into account, and momentum and energy integral equations for the turbulent boundary layer are applied. This study is aimed to analyze the post-shock expansion caused by the shock/boundary layer interaction. The results show that the post-shock expansion is largely positioned outside the edge of boundary layer and the extent of it scales with the flow Mach number, and also show the qualitative agreement with experimental results.

VAPOR-SCREEN METHOD FOR FLOW VISUALIZATION IN AN INDRAFT SUPERSONIC NOZZLE

The vapor-screen method, a simple and practical method of flow visualization for high speeds, has been applied to supersonic flow field generated in an indraft supersonic nozzle. As the result, the condition of visualization has been clarified and it has been demonstrated that this method is very useful to visualize flows in the indraft tunnel.

Visualization of Shock Waves in a Supersonic Nozzle by Vapor-Screen Method

The vapor-screen method is a simple and practical method of flow visualization for high speeds. In the present paper, it has been applied to shock waves generated in a supersonic nozzle, and the photograph has been compared with that of shadowgraph method. As the result, it has been demonstrated that this method is very useful to visualize shock waves.

Visualization of high speed flow field by vapor-screen method.

The vapor-screen method, a simple and practical method of flow visualization for high speeds, has been applied to subsonic flow field generated in a shock tube. As the result, the condition of visualization has been clarified and it has been demonstrated that this method is very useful to visualize compressible flows past a model with its wake.