JABEE ノ エンジニア デザイン キョウイク エ ノ カツドウ ホウコク : リュウタイ コウザ ノ カツドウ ドルフィン ジャンプ

九州地区総合技術研究会in熊本大学, 第21回情報処理センター等担当者技術研究会(2009年9月3.4日開催)　ポスター発表

Performance of Wide-Angle Two-Dimensional Diffusers with Vane Systems (3rd Report)

In the previous works, experiments were made with flat vanes in diffusers with divergence angles of 30°, 40°, and 60°, and showed the basic criteria for effective vane configurations with source-point translation. In the present work, tests were made with flat vanes in two-dimensional diffusers, to determine the relation between pressure recovery and flow regime. For the optimum vane configurations with source-point translation on the pressure recovery, the flow regime in the downstream duct is also greatly improved. The area of separation is considerably reduced, and the velocity profiles in the downstream duct can be flattened. However, the section where the velocity profile is to be uniform can be attained at the far distance in the downstream duct, compared with the pressure recovery section

Performance of the Wide-Angle Two-Dimensional Diffusers with Various Inlet Shear Flows (1st Rept. In Case of Uniform Shear Flows)

Experimental studies of the two dimensional diffusers with inlet uniform shear flows in the parallel walls were carried out. In general, the performance of the diffusers with inlet simple shear flows for small divergence angle was lower compared with the diffusers having uniform inlet velocity profiles. However, the pressure-recovery performance of wide-angle diffusers with uniform inlet shear flows was slightly higher than that of the diffusers with uniform inlet velocity profiles. This is characterized by the effects of the variations of spanwise velocity gradients and the secondary flows in the diffusers

Study on Flow in the Two-Dimensional Curved Diffuser

Curved diffusers are used in pipe lines or in some fluid machineries, such as blades of impeller, a volute casing, or suction duct. The performance of the curved diffuser has a considerable effect on the energy conversion in the pipe lines or the machineries. Furthermore, the volute casing in the pumps or blowers is generally attached to the radial diffuser, so that the flow in the volute or scroll casing has usually very high complexities. The flow in the volute casing will be moderated by the combination of the single curved diffuser and the longitudinal side wall slit duct. However, the studies to the flow in the curved diffuser with the longitudinal slit, were merely conducted in the past ages. In this report, as a step of the study of the flow in the volute casing, experiments of flow in a two-dimensional curved diffuser, which has a small diverging angle and 90° turning angle, were carried out. The time average velocities and velocity fluctuations were measured using a constant temperature hot-wire or split film probe system. It is shown that the flow in the curved diffuser has velocity profiles with gradually variant gradients and attached to the outer side wall, and the profiles of velocity fluctuations have very interesting patterns concernig to the stall and the secondary flow