Measurements of turbulent developing flow in a moderately curved square duct

Enayet, M.M.; Gibson, M. M.; Yianneskis, M.

doi:10.1016/0142-727x(82)90027-3

Cited by 18 publications

(2 citation statements)

References 3 publications

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“…Over the last ten years, approximately, a substantial amount of experimental information has been obtained for developing turbulent flows in curved ducts of rectangular cross-section [1][2][3][4][5][6][7]. Detailed measurements in these important flow configurations, in particular of the secondary motions and complex turbulent characteristics which they induce, have been made possible by the non-intrusive laser-Doppler velocimetry technique.…”

Section: The Problem Of Interest and Earlier Workmentioning

confidence: 99%

Developing Turbulent Flow in a U-Bend of Circular Cross-Section: Measurement and Computation

Azzola

Humphrey

Iacovides

et al. 1986

Journal of Fluids Engineering

101

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Laser-Doppler measurements of the longitudinal and circumferential velocity components are reported for developing turbulent flow in a strongly curved 180 deg pipe and its downstream tangent. In the bend, the mean longitudinal velocity component changes little after θ = 90 deg, but the circumferential component never achieves a fully-developed state. Similar behavior is observed in the normal stresses, with large levels of flow anisotropy arising everywhere in the bend and downstream tangent. Between θ = 90 deg and X/D = 5, the circumferential velocity profiles display reversals of the secondary flow which are essentially independent of the Reynolds number. Predictions of the flow development are presented based on a “semi-elliptic” truncation of the Reynolds equations in the main part of the flow with the standard k-ε effective viscosity model used to approximate the turbulent stress field. In the immediate vicinity of the wall a simpler treatment, PSL, is adopted that allows the inclusion of the very fine mesh needed to resolve the viscous sublayer without excessive computer storage. The calculated behavior displays reasonably good agreement with the measurements in the bend, including the secondary flow reversals. Downstream of the bend, however, the rate of recovery of the flow is too slow, which points to the same weakness in the turbulence model as found in the recovery region of the flow over a backward-facing step.

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Section: The Problem Of Interest and Earlier Workmentioning

confidence: 99%

Developing Turbulent Flow in a U-Bend of Circular Cross-Section: Measurement and Computation

Azzola

Humphrey

Iacovides

et al. 1986

Journal of Fluids Engineering

101

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show abstract

“…A number of experimental studies has been reported on the pressure losses and flow structures in turbulent flow in pipe bends of circular and square cross sections [2][3][4][5][6][7], various bend angles [8][9][10], and with turning vanes [3,11]. It was shown that the pressure loss coefficient, velocity distribution, and turbulent intensities were strongly influenced by the bend angle, Reynolds number, and the turning vanes.…”

Section: Literature Reviewmentioning

confidence: 97%

Numerical investigation of pressure loss reduction in a power plant stack

Lakshmiraju

Cui

2007

Applied Mathematical Modelling

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The strengthened environmental laws require the power plants to reduce the emissions. Flue gas desulphurization and deNO x involve adding chemicals to the flow stream, thereby resulting in increased mass flow. This problem could be overcome by reducing the pressure drop in the duct work and stack combination, so that a higher flow at reduced pressure drop can be handled by the existing fans. In this study, a power plant stack model of 1:40 was investigated numerically. The pressure reduction was achieved by introduction of baffles with various orientations and turning vanes at the inlet of the stack. The flows were modeled and analyzed using commercial computational fluid dynamics (CFD) software Fluent 6.2. The numerical results were validated with the experimental data. The 30°baffle without turning vanes was found to be the optimum baffle angle in terms of the pressure loss reduction. Variation of axial velocity, swirling component and turbulence kinetic energy along the axis of the stack was analyzed to understand the mechanism of the pressure loss reduction in a power plant stack. Guidelines for further pressure loss reduction were provided based on the insight gained from the simulation results.

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Secondary Flows in Axial-Flow Compressors

Serovy¹

1985

Thermodynamics and Fluid Mechanics of Turbomachinery

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Measurements of turbulent developing flow in a moderately curved square duct

Cited by 18 publications

References 3 publications

Developing Turbulent Flow in a U-Bend of Circular Cross-Section: Measurement and Computation

Developing Turbulent Flow in a U-Bend of Circular Cross-Section: Measurement and Computation

Numerical investigation of pressure loss reduction in a power plant stack

Secondary Flows in Axial-Flow Compressors

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