Toshimichi Sakai

Development of a velocimeter by use of a laser diode.

A velocimeter was developed which measured the frequency of the Karman vortex downstream of a wire of small diameter which was set perpendicular to the water flow in a channel. The frequency of the Karman vortex was measured by the focused light of a laser diode which scanned downstream along the wire. The wire was heated by applying alow-voltage electrical charge which strengthened the refraction of the light resulting in a density change of the fluid. The velocity distribution could then be measured. THE following results were obtained : 1) the frequency and the velocity was linear ; 2) influence to the fluid was negligible though it was not noninvasive ; and 3) drift due to the terperature change was negligibly small.

Investigation Concerning the Fluid Flow in the Mixed-Flow Diffuser

Velocity profile measurements were performed on the flow in a mixed-flow diffuser with walls having equal cone angles. The aim of the present study is to understand the flow behavior and the relation between the flow patterns and the diffuser losses. The boundary layer flow accompanied by separation on the inner wall and the velocity normal to the diffuser walls were measured in detail to examine the three-dimensional flow behavior in the mixed-flow diffuser. Comparing with the radial diffuser, the mixed-flow diffuser had a more complicated flow mechanism as it had the pressure gradients of transverse and normal directions.Copyright

A study of radially curved mixed-flow vaneless diffusers. Diffusers to give possibly small static pressure gradient normal to the walls over the entire flow passage.

For radially curved mixed-flow vaneless diffusers, the authors clarified that the diffusers having small static pressure gradient normal to the walls give favorable inner flow and high performances. In this study, from this concept a design method to give a small static pressure gradient normal to the walls at any section in a radially curved mixed-flow vaneless diffuser flow passage was established. Flow measurements showed that a favorable inner flow and high performance could be obtained by use of this method.

A Study on the Flow Pattern Within the Centrifugal and Mixed-Flow Impellers

An Investigation of the flow patterns within the centrifugal and mixed-flow impeller channel were performed. The velocity distributions within the impeller channel and blade surface pressure of the centrifugal and mixed-flow impellers were closely examined by experiment and the flow behavior within these impellers were clarified. The incompressible and inviscid flow within the impellers having straight radial blades were also derived analytically. The present authors assumed an outermost boundary of the relative eddy at the impeller exit periphery and corrected the analytical results. The corrected analytical results thus obtained showed good coincidence with the experimental data.Copyright