Behavior of secondary flow in a low solidity tandem cascade diffuser

Daisaku Sakaguchi, Hironobu Ueki, Masahiro Ishida, Hiroshi Hayami

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Abstract

Low solidity circular cascade diffuser abbreviated by LSD was proposed by Senoo et al. showing a high blade loading or a high lift coefficient without stall even under small flow rate conditions. These high performances were achieved by that the flow separation on the suction surface of the LSD blade was successfully suppressed by the secondary flow formed along the side walls. The higher performance of the LSD was achieved in both pressure recovery and operating range by adopting the tandem cascade because the front blade of the tandem cascade was designed suitably for small flow rates while the rear blade of the tandem cascade was designed suitably for large flow rates. In order to clarify the reason why the tandem cascade could achieve a high pressure recovery in a wide range of flow rate, the flow in the LSD with the tandem cascade is analyzed numerically in the present study by using the commercial CFD code of ANSYS-CFX 13.0. The behavior of the secondary flow is compared between the cases with the single cascade and the tandem one. It is found that the high blade loading of the front blade is achieved at the small flow rate by formation of the favorable secondary flow which suppresses the flow separation on suction surface of the front blade, and the flow separation on pressure surface of the front blade appeared at the design flow rate can be suppressed by the accelerated flow in the gap between the trailing edge of the front blade and the leading edge of the rear blade, resulting in the positive lift coefficient in spite of a large negative angle of attack.

Original languageEnglish
Title of host publicationASME Turbo Expo 2012
Subtitle of host publicationTurbine Technical Conference and Exposition, GT 2012
Pages763-770
Number of pages8
DOIs
Publication statusPublished - 2012
Externally publishedYes
EventASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012 - Copenhagen, Denmark
Duration: Jun 11 2012Jun 15 2012

Publication series

NameProceedings of the ASME Turbo Expo
Volume3

Other

OtherASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012
Country/TerritoryDenmark
CityCopenhagen
Period6/11/126/15/12

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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