Nobumasa Kawaguchi

Pressure Recovery of Collectors With Annular Curved Diffusers

Pressure recovery is examined for axisymmetric annular curved diffusers with various values of inlet/exit area ratio. The conditions of inlet flow include three swirl angles and two values of boundary layer blockage. Then, one of the diffuser is connected to two types of collectors with different size. The discharge pressure is decreased by the collector. The cause is not deterioration of diffuser performance due to asymmetric pressure distribution but formation of a cork screw type vortex flow inside the collector. An attempt to retard the vortex motion was successful by inserting obstructions in the collector. If a large size collector is used together with proper obstructions inside the collector, pressure-rise is possible in the collector rather than pressure drop.Copyright

Blade Loading of Transonic Circular Cascade Diffuser.

A low-solidity circular cascade, conformally transformed from a high-stagger linear cascade of double-circular-arc vanes with solidity 0.69, was tested as a part of the diffuser system of a transonic centrifugal compressor, and the blade loading of the cascade was investigated by means of pressure measurement around the vane. The experimental data for the lift-coefficient of the vane were almost on a single straight line when plotted against angle-of-attack for a wide range of Mach numbers and flow angles. The maximum lift-coefficient reached about 1.5 and the vane functioned well even near the surge condition of the compressor.

Visualization of Mixing Process in a Cell Mixer Agitated by a Piezoelectric Vibrating Stirrer

The mixing process in a cell mixer by a piezoelectric vibrating actuator as a stirrer was visualized by means of a dye-tracer method and was pictured using a video camera. The local concentration of dye was transformed to a gray scale using an image processing technique. The quantitative information on 2D mixing process as well as the flow pattern were deduced and discussed by the image processing. The time variation in the probability density function of gray scale for the whole area as well as the time variation in the local gray scale were also discussed.

Effects of Secondary Flow Along End-Wall on Stall Limits of Circular

小弦節比円形翼列ディフューザの失速限界が、翼列側壁面の二次流れの挙動と関数があることを油膜法によって確かめ、翼まわりのポテンシャル流れから予測される圧力分布と二次流れの対応を調べた。その結果、翼数、弦節比やくい違い角などを適切に選べば、二次流れを利用して高い圧力回復率と広い運転範囲とが実現できるディフューザの設計が可能であることを示した。