Limits of Flow Separation of Inward Flow in Axisymmetric L-turn Passage

1986 Fiscal Year Final Research Report Summary

• Project/Area Number: 60550138
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Fluid engineering
• Research Institution: Ikutoku Technical University
• Principal Investigator: AKAIKE Shiro Ikutoku Technical University, 工学部, 教授 (50017919)
• Co-Investigator(Kenkyū-buntansha): NEMOTO Mitsumasa Ikutoku Technical University, 工学部機械工学科, 助手 (90085134)
• Project Period (FY): 1985 – 1986
• Keywords: Centrifugal Turbomachinery / Axisymmetric L-turn Passage / Swirling Flow / Secondary Flow / 流れのはく離

Research Abstract

Axisymmetric L-turn passage is an important stationary component of centrifugal turbomachinery. This study is intended to clarify the behaivor of a swirling flow through the L-turn passage. Three model passages which have the constant width b=40mm and that the radius <R_0> of the curvature of the bend differs from <R_0> /b=1 to 2, were tested by using air as the working fluid. Velocity distributions in the passage and pressure distributions along the passage walls were measured. Experiments were carried out for the mean flow angle <alpha_0> <<![> 70゜ measured from the peripheral direction at the datum section upstream of the L-turn bend. The results obtained are mainly as follows.
1. In the limits of this experiment, the flow conditons in the three passages are almost the same. When the mean flow angle <alph_0> is small, the secondary flow along the inner wall in the bend develops considerably. When <alpha_0> becomes large, the distributions of the meridian velocity component in the passage agree well with the potential flow. The flow separation does not occur. 2. When <alpha_0> <>![> 30゜, the pressure distributions along the both walls agree with the distributions obtained from the potential flow. When <alpha_0> <<![> 30゜, the agreement between the both is not good because of the development of the secondary flow.
3. The variation of the total pressure loss coefficient <zeta> with <alpha_0> is scarcely affected by the radius of the curvature of the bend at <alpha_0> <<![> 70゜. The minimum value of <zeta> is obtained at <alpha_0> <:!=> 70゜ and <zeta> increases considerably according to the decrease of <alpha_0> at <alpha_0> <<![> 30゜.
We are going to continue this project, because the limits of the flow separation in the L-turn passage is not made clear in this experiment of <alpha_0> <<![> 70゜.

Research Products

• [Publications] 赤池志郎: ターボ機械.
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Shiro AKAIKE, at al.: "Inward Flow in Axisymmetric L-turn Passage" Turbomachinery.
  • Description: 「研究成果報告書概要(欧文)」より