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Measurements of the transient velocity field in a strongly curved diffusing bend with periodic inflow unsteadiness

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Abstract

This study examined the effects of periodic inflow unsteadiness on the flow development through fishtail-shaped diffusers utilized on small gas turbine engines. The periodic unsteadiness is due to the distortion of the flow in the peripheral direction at the exit of the centrifugal compressor impeller, caused by the jet-wake type of flow discharging from each impeller passage. Measurements of the transient velocity field were performed throughout the diffuser using a miniature 4-wire probe, at frequencies of inflow unsteadiness corresponding to design and off-design operating conditions in gas turbine installations. At the low end of the tested inflow unsteadiness frequencies, significant effects of inflow unsteadiness were observed on the time-averaged flow distortion throughout the diffuser. At these frequencies, the time variation of flow distortion was found to remain at comparable magnitudes throughout the diffuser.

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Abbreviations

A :

local cross-sectional area

h :

half-height of the diffuser side walls; refer to Fig. 2a

L :

diffuser centerline length

r :

radius of the upper and lower walls; refer to Fig. 2a

V :

velocity

V̄ :

area-averaged velocity

v rms :

root-mean-square of the fluctuating component (V–V **) of velocity

x, y, z :

orthogonal curvilinear coordinates; x axis is tangent to the centerline of the flow path with x=0 at the inlet of the diffuser; refer to Fig. 2a

α P :

primary-flow kinetic energy factor (Eq. 1)

θ :

turning angle of the diffuser centerline; refer to Fig. 2a

ϕ :

circumferential coordinate; refer to Fig. 2a

ω :

vorticity, normalized by the radius of plane A and \( \bar{V}^{{**}}_{x} \) in the corresponding measurement plane

CL:

centerline

x, y, z :

components in the x, y and z directions

A, B, C, D, E:

cross-sectional measurement planes; refer to Table 1 for their locations

*:

ensemble-averaged quantity

**:

time-averaged quantity

References

  • Bearman PW (1971) Corrections for the effect of ambient temperature drift on hot-wire measurements in incompressible flow. DISA Information Report No. 11, pp. 25–30

  • Blair LW, Russo CJ (1980) Compact diffusers for centrifugal compressors. AIAA Paper 80-1077, presented at the AIAA/SAE/ASME 16th Joint Propulsion Conference

  • Dobbeling K, Lenze B, Leuckel W (1990) Computer-aided calibration and measurements with a quadruple hotwire probe. Exp Fluids 8:257–262

    Google Scholar 

  • Fox RW, Kline SJ (1962) Flow regimes in curved subsonic diffusers. J Basic Eng 84:303–316

    Google Scholar 

  • Kenny DP (1968) A novel low cost diffuser for high performance centrifugal compressors. ASME Paper 68-GT-38

  • Krain H (1981) A study of centrifugal impeller and diffuser flow. J Eng Power 103:688–697

    Google Scholar 

  • McMillan OJ (1982) Mean-flow measurements of the flow field diffusing bend. NASA Contractor Report 3634

  • Parsons DJ, Hill PG (1973) Effects of curvature on two-dimensional diffuser flow. J Fluids Eng 95:349–360

    Google Scholar 

  • Reeves GB (1977) Design and performance of selected pipe-type diffusers. ASME Paper 77-GT-104

  • Sagi CJ, Johnston JP (1967) The design and performance of two-dimensional, curved diffusers. J Basic Eng 89:715–731

    Google Scholar 

  • Wellborn SR, Reichert BA, Okiishi TH (1992) An experimental investigation of the flow in a diffusing S-duct. AIAA Paper 92-3622 presented at the AIAA/SAE/ASME/ASEE 28th Joint Propulsion Conference

  • Yaras MI (1996) Effects of inlet conditions on the flow in a fishtail curved diffuser with strong curvature. J Fluids Eng 118:772–778

    CAS  Google Scholar 

  • Yaras MI (1999) Flow measurements in a fishtail diffuser with strong curvature. J Fluids Eng 121:410–417

    Google Scholar 

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Acknowledgments

The authors gratefully acknowledge the research grant provided by the Natural Sciences and Engineering Research Council of Canada in support of this project.

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Authors and Affiliations

  1. Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa, K1S 5B6, Canada

    M. I. Yaras & P. Orsi

Authors
  1. M. I. Yaras
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  2. P. Orsi
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Correspondence to M. I. Yaras.

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Yaras, M.I., Orsi, P. Measurements of the transient velocity field in a strongly curved diffusing bend with periodic inflow unsteadiness. Exp Fluids 36, 363–372 (2004). https://doi.org/10.1007/s00348-003-0734-6

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  • DOI: https://doi.org/10.1007/s00348-003-0734-6

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