Unsteady flow in the vaned diffuser of a low specific speed centrifugal pump with an unshrouded impeller

Asuma Ichinose, Tomoki Takeda, Kazuyoshi Miyagawa, Yohei Ogawa, Hideyo Negishi, Kazuki Niiyama

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

Abstract

The unsteady internal flow in a low specific speed centrifugal pump was experimentally and numerically investigated. Unshrouded impellers enable high head designs but on the other hand, they exhibit complicated internal flow and an efficiency decline compared to shrouded impellers. Furthermore, the complicated impeller outlet flow induces unsteady internal flow in the vaned diffuser. Therefore, a detailed investigation of the internal flow is required in order to increase the efficiency of these low specific speed centrifugal pumps. The aims of this paper are to clarify the loss mechanisms in the impeller and to investigate the effect of impeller outlet flow to the diffuser internal flow at the design point. The detailed pump internal flow is investigated using unsteady computation, which enables the computation of the 3D flow pattern. The reversed flow and the secondary flow are induced by the tip leakage flow, and this creates a high loss region in the blade-to-blade region. On the other hand, the mixing effect is remarkable at the impeller outlet, and this affects the creation of the wake. This flow behavior makes the internal flow of the diffuser unsteady and the diffuser performance fluctuates due to the impeller wake at the design point.

Original languageEnglish
Title of host publicationFluid Applications and Systems
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791859056
DOIs
Publication statusPublished - 2019
EventASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019 - San Francisco, United States
Duration: 2019 Jul 282019 Aug 1

Publication series

NameASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019
Volume3B-2019

Conference

ConferenceASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019
CountryUnited States
CitySan Francisco
Period19/7/2819/8/1

Keywords

  • Impeller wake
  • Loss mechanism
  • Tip leakage flow
  • Unshrouded impeller

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes

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    Ichinose, A., Takeda, T., Miyagawa, K., Ogawa, Y., Negishi, H., & Niiyama, K. (2019). Unsteady flow in the vaned diffuser of a low specific speed centrifugal pump with an unshrouded impeller. In Fluid Applications and Systems [5599] (ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference, AJKFluids 2019; Vol. 3B-2019). American Society of Mechanical Engineers (ASME). https://doi.org/10.1115/AJKFluids2019-5599