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Exit-flow velocity survey of two single-tangential-inlet vaneless turbine volutes

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Title: Exit-flow velocity survey of two single-tangential-inlet vaneless turbine volutes
Authors: Fuller, Adam M. adam.fuller@pg.canterbury.ac.nz, Alexander, Keith V.1 keith.alexander@canterbury.ac.nz
Source: Experimental Thermal & Fluid Science. Jan2011, Vol. 35 Issue 1, p48-59. 12p.
Subjects: Two-phase flow, Pressure measurement, Hydraulic turbines, Reynolds number, Reynolds stress, Computational fluid dynamics
Abstract: Abstract: The most cited analytical technique for designing turbine volutes is to assume the throughflow is free from torque, although for this assumption to hold, the volute walls must lie near what would be streamlines in an unbounded free vortex-plus-sink flow. The single tangential inlet design, with inlet offset decreased and diameter increased to attain the weak exit swirl required by high specific speed turbines, deviates from such a shape, and the volute’s internal geometry is no longer torque-free. It is desired to know the actual time-averaged flow leaving such a volute, so that a rotor can be designed to compliment it. For two existing single tangential inlet volutes, time-averaged radial and tangential velocity and static pressure measurements of exit flow have been obtained on a cylindrical cut plane through the radial-inflow section using a three-port yawmeter in air. The Reynolds numbers based on inlet pipe mean conditions, around 105, are well into the fully-turbulent regime and on the order of comparable water turbines. A comprehensive map of time-averaged exit flow of both volutes is presented. The integrated values of gross angular momentum flux change and total pressure loss coefficient are tabulated. Circumferential variation of flowrate and swirl strength highlight unexpected differences in outlet flow between the two volute designs. Results are presented alongside corresponding numerical results from the commercial package Fluent (Fluent, Inc., Lebanon, NH, USA) using Reynolds stress, k–ω, and inviscid flow models. In both volutes, measured gross exit angular momentum flux was more than 1.7 times what the zero-torque assumption would predict when blindly applied to the volute as a whole. This discrepancy is attributed to significant turning near the volute’s inlet region leading to an updated view of what an appropriate control volume is when applying the zero-torque assumption. Additionally, variation of both radial and tangential velocity in both the circumferential and axial directions on the order of 15% of the mean value reveal that volute swirl characterization by a single measurement would have a significant associated uncertainty. [Copyright &y& Elsevier]
Copyright of Experimental Thermal & Fluid Science is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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DbLabel: Engineering Source
An: 54879432
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  Label: Title
  Group: Ti
  Data: Exit-flow velocity survey of two single-tangential-inlet vaneless turbine volutes
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  Data: <searchLink fieldCode="AR" term="%22Fuller%2C+Adam+M%2E%22">Fuller, Adam M.</searchLink><i> adam.fuller@pg.canterbury.ac.nz</i><br /><searchLink fieldCode="AR" term="%22Alexander%2C+Keith+V%2E%22">Alexander, Keith V.</searchLink><relatesTo>1</relatesTo><i> keith.alexander@canterbury.ac.nz</i>
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  Data: <searchLink fieldCode="JN" term="%22Experimental+Thermal+%26+Fluid+Science%22">Experimental Thermal & Fluid Science</searchLink>. Jan2011, Vol. 35 Issue 1, p48-59. 12p.
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  Data: <searchLink fieldCode="DE" term="%22Two-phase+flow%22">Two-phase flow</searchLink><br /><searchLink fieldCode="DE" term="%22Pressure+measurement%22">Pressure measurement</searchLink><br /><searchLink fieldCode="DE" term="%22Hydraulic+turbines%22">Hydraulic turbines</searchLink><br /><searchLink fieldCode="DE" term="%22Reynolds+number%22">Reynolds number</searchLink><br /><searchLink fieldCode="DE" term="%22Reynolds+stress%22">Reynolds stress</searchLink><br /><searchLink fieldCode="DE" term="%22Computational+fluid+dynamics%22">Computational fluid dynamics</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Abstract: The most cited analytical technique for designing turbine volutes is to assume the throughflow is free from torque, although for this assumption to hold, the volute walls must lie near what would be streamlines in an unbounded free vortex-plus-sink flow. The single tangential inlet design, with inlet offset decreased and diameter increased to attain the weak exit swirl required by high specific speed turbines, deviates from such a shape, and the volute’s internal geometry is no longer torque-free. It is desired to know the actual time-averaged flow leaving such a volute, so that a rotor can be designed to compliment it. For two existing single tangential inlet volutes, time-averaged radial and tangential velocity and static pressure measurements of exit flow have been obtained on a cylindrical cut plane through the radial-inflow section using a three-port yawmeter in air. The Reynolds numbers based on inlet pipe mean conditions, around 105, are well into the fully-turbulent regime and on the order of comparable water turbines. A comprehensive map of time-averaged exit flow of both volutes is presented. The integrated values of gross angular momentum flux change and total pressure loss coefficient are tabulated. Circumferential variation of flowrate and swirl strength highlight unexpected differences in outlet flow between the two volute designs. Results are presented alongside corresponding numerical results from the commercial package Fluent (Fluent, Inc., Lebanon, NH, USA) using Reynolds stress, k–ω, and inviscid flow models. In both volutes, measured gross exit angular momentum flux was more than 1.7 times what the zero-torque assumption would predict when blindly applied to the volute as a whole. This discrepancy is attributed to significant turning near the volute’s inlet region leading to an updated view of what an appropriate control volume is when applying the zero-torque assumption. Additionally, variation of both radial and tangential velocity in both the circumferential and axial directions on the order of 15% of the mean value reveal that volute swirl characterization by a single measurement would have a significant associated uncertainty. [Copyright &y& Elsevier]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Experimental Thermal & Fluid Science is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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        Value: 10.1016/j.expthermflusci.2010.08.005
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        Text: English
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        PageCount: 12
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        Type: general
      – SubjectFull: Pressure measurement
        Type: general
      – SubjectFull: Hydraulic turbines
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      – SubjectFull: Reynolds number
        Type: general
      – SubjectFull: Reynolds stress
        Type: general
      – SubjectFull: Computational fluid dynamics
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    Titles:
      – TitleFull: Exit-flow velocity survey of two single-tangential-inlet vaneless turbine volutes
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            NameFull: Fuller, Adam M.
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              Text: Jan2011
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              Y: 2011
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