Sage Journals: Discover world-class research

Abstract

An experimental study was made of an incompressible flow through a model S-shaped semicircular to circular transition diffusing duct. The transition diffuser has a length—exit diameter ratio of 3 and a duct offset ratio of 0.3. The operating Reynolds number based on hydraulic diameter and bulk velocity is 40 000. The refraction index matching technique and laser Doppler velocimetry were used for velocity measurements. The measurements indicate that flow distortion persists at the outlet and the separation of the boundary layers is incipient. Semicircular to circular transition duct flow was studied in order to document the transition duct flow field and to provide detailed duct flow data for comparison with numerical code prediction. Experimental results also suggest that details of the near-wall flow incipient separation region and the distortion of the flow in the second half of the diffuser are likely to provide a severe test for various computational methods and turbulence models.

Keywords

turbulent flow transition duct S-diffuser S-bends index of refraction matching techniques laser Doppler anemometry turbulence level vortex boundary layer

Get full access to this article

View all access options for this article.

References

Taylor

A. M. K. P.

Whitelaw

J. J.

Yianneskis

Developing flow in S-shaped ducts. Part I: square cross-section duct. NASA Contractor Report 3550, 1992.

Enayet

M. M.

Gibson

M. M.

Yianneskis

Measurements of turbulent developing flow in moderately curved square duct. Int. J. Heat and Fluid Flow, 1982, 3, 221.

Humphrey

J. A. C.

Chang

S. M.

Modavi

Development of turbulent flow in 180 bend and downstream tangent of square cross-section. Physico Chem. Hydrodynamics, 1983, 4, 243.

Rojas

Flow and heat transfer characteristics of diffusing curved ducts. PhD thesis, University of London, 1986.

Whitelaw

J. H.

S. C. M.

Turbulent flow characteristics in an S-shaped diffusing duct. Flow Measmt and Instrum., 1993, 4(3), 171–179.

Chyu

W. J.

Bencze

D. P.

Navier-Stokes simulation of flow through a highly subsonic diffuser. Int. J. for Numer. Meth. in Engng, 1992, 34, 473–483.

Nouri

J. M.

Whitelaw

J. H.

Yianneskis

A refractive Index matching technique for solid/liquid flows. Laser Anemometer in Fluid Mechanics, 1988, 3, 355.

Durst

Melling

Whitelaw

J. H.

Principles and Practice of Laser Doppler Anemometer, 2nd edition, 1981 (Academic Press).

McLaughlin

D. K.

Tiderman

W. G.

Biasing correction for individual realisation of laser anemometer measurements in turbulent flows. Phys. Fluids, 1973, 16, 2082–2088.

10.

Yanta

W. J.

Smith

R. S.

Measurements of turbulence-transport properties with laser Doppler velocimeter. In AIAA 11th Aerospace Science Meeting, Washington, 1978, paper 73-169.

11.

Humphrey

J. A. C.

Flow in ducts with curvature and roughness. PhD thesis, University of London, 1977.

12.

Anwer

R. M. C.

Lai

Y. G.

Perturbation by recovery from bend curvature of fully developed turbulent pipe flow. Phys. Fluids (A), 1989, 1(8), 1387–1397.

Flow characteristics inside a diffuser of complex shape

Abstract

Abstract

Keywords

Get full access to this article

References