cases:case052

# Duct Flows with Smooth and Rough Walls

Experimental data is presented for fully developed turbulent flow in square and rectangular ducts with combinations of smooth and roughened walls. Two configurations are included here, as shown in figure 1:

• A square duct with two opposite walls roughened
• A rectangular 2:1 aspect ratio duct with the long base wall roughened

The flow was measured by means of hot-wire anemometry.

Fig. 1: Experimental configurations and coordinate system

#### Experimental Configuration

Air was supplied by a centrifugal blower into a test duct after measuring the flow by means of a quadrant flow nozzle and settling the flow in the settling chamber with three wire-nets spread which have different meshes from each other. The test ducts were 50 mm square, or 50 mm by 100 mm rectangular, cross-section and at least 4500 mm in length. Roughness elements whose cross-section was 1 mm square were placed at 10 mm intervals, transverse to the primary flow, to make up the roughened walls of the ducts.

The Reynolds number, based on bulk mean velocity and hydraulic diameter, was $6.5\times 10^4$ in both cases.

Measurements were conducted at the duct cross-section a little upstream from the duct exit. Mean and fluctuating velocities were measured by using a hot wire anemometer with an I- and an X-wire probe whose sensing parts were 1 mm in length. As for the secondary currents and turbulent shear stresses, each measurement was performed using two kinds of X-wire probes, one the reflected image of the other, separately. Then the results obtained by the two probes were averaged in order to decrease the error.

#### Measurement Errors

The maximum uncertainties involved in measured values were estimated as follows:

 $U_1$ +/-1.5% +/-3.3% +/-3.3% +/-7.3% +/-7.3% +/-6.3% +/-6.3%

Data available includes:

• Maps of mean velocities $U$, $V$ and $W$ across the ducts
• Maps of rms velocities $u'$, $v'$, $w'$ and shear stresses $overline{u_1u_2}$ and $\overline{u_1u_3}$ across the ducts

Sample plots of selected quantities are available.

The data files can be downloaded as compressed archives from the links below, or as individual files from the table.

Square Duct Rectangular Duct
Mean $U$ velocity su1-1.dat lu1-1.dat Profiles across ducts at selected $x_3/B$ locations
su1-2.dat lu1-2.dat Profiles across ducts at selected $x_2/B$ locations
Mean $V$ velocity su2.dat lu2.dat Profiles across ducts at selected $x_3/B$ locations
Mean $W$ velocity su3.dat lu3.dat Profiles across ducts at selected $x_3/B$ locations
Rms $u'$ velocity srmsu1-1.dat lrmsu1-1.dat Profiles across ducts at selected $x_3/B$ locations
srmsu1-2.dat lrmsu1-2.dat Profiles across ducts at selected $x_2/B$ locations
Rms $v'$ velocity srmsu2-1.dat lrmsu2-1.dat Profiles across ducts at selected $x_3/B$ locations
srmsu2-2.dat lrmsu2-2.dat Profiles across ducts at selected $x_2/B$ locations
Rms $w'$ velocity srmsu3-1.dat lrmsu3-1.dat Profiles across ducts at selected $x_3/B$ locations
srmsu3-2.dat lrmsu3-2.dat Profiles across ducts at selected $x_2/B$ locations
$\overline{uv}$ shear stress su1u2-1.dat lu1u2-1.dat Profiles across ducts at selected $x_3/B$ locations
su1u2-2.dat lu1u2-2.dat Profiles across ducts at selected $x_2/B$ locations
$\overline{uw}$ shear stress su1u3-1.dat lu1u3-1.dat Profiles across ducts at selected $x_3/B$ locations
su1u3-2.dat lu1u3-2.dat Profiles across ducts at selected $x_2/B$ locations
1. Fujita, H., Yokosawa, H., Hirota, M., Nagata, A.C. (1988). Fully developed turbulent flow and heat transfer in a square duct with two roughened facing walls. Chem. Eng. Comm., Vol. 74, pp. 95-110.
2. Fujita, H., Hirota, M., Yokosawa, H., Hasegawa, M., Gotoh, I. (1990). Fully developed turbulent flows through Rectangular Ducts with One Roughened Wall. JSME Int. J., Vol. 33, pp. 692-701.

Indexed data:

case052 (dbcase, confined_flow)
case052
titleDuct flows with smooth and rough walls
authorFujita, Hirota, Yokosawa, Hasegawa, Gotoh, Nagata
year1988
typeEXP
flow_tag3d, wall_roughness, constant_cross_section