Square-Section Duct 180 Degree Bend

Experiments by Choi

Description

Turbulent flow in a square cross-section duct made of a 180^o bend and two long straight inlet and outlet parts. 3D flow with constant temperature.

Geometry of the Computational Domain

180^o bend section connected to straight inlet and outlet tangents, all of square section: D × D = 88.9 × 88.9 mm. Centreline curvature radius of the bend: R_c = 3.357D.

Flow Parameters

Air at standard conditions.

• Kinematic viscosity: = 1.72×10^-5 m²/s.
• Inlet bulk axial velocity W_B = 11 m/s.
• Reynolds number based on the bulk axial velocity W_B: Re = W_BD/ = 56,690.

Inflow Conditions

The following measurements are available for the cross section located at z = -D. They correspond to a fully developed turbulent in a square section duct.

Contour maps as f(x,y) of:

• First order moments: U, V, W
• Second order moments
• Turbulent kinetic energy: k/W_B² (deduced)

Additional values of k and issued by numerical simulations are also available in the file input.

Experimental Details

Velocity measurements using a rotatable hot-wire probe.

Measurement Errors

Analyzed but no published values.

Available Measurements

Contour maps at 5 different angular positions ( = 0^o, 45^o, 90^o, 135^o, 180^o) of:

• First order moments: U/W_B, V/W_B, W/W_B
• Second order moments: u'/W_B, v'/W_B, w'/W_B, /W_B², /W_B², /W_B²
• Turbulent kinetic energy: k/W_B²

Previous and Reference Numerical Solutions

None available yet.

Main References

1. CHOI, Y.D., MOON C. & Yang, S.H. (1990). Measurment of turbulent flow characteristics of square duct with a 180 degree bend by not wire anemometer. International Symp. on Engineering Turbulenze modelling and measurement, (no page numbers).
2. CHOI, Y.D., IACOVIDES, H. & LAUNDER, B.E. (1989). Numerical computation of turbulent flow in a square-sectioned 180 deg bend. J. Fluids Engg 111, 59, (see Chang, Physico-Chem. Hydr. 4, 243, 1983 for expts.).
3. SOTIROPOULOS, F. AND PATEL, V.C. (1993). Evaluation of some near-wall models for the reynolds-stress transport equations in a complex 3-d shear flow. Near wall turbulent flows, pp. 987.