Table 1: Selected experimental studies with turbulent flow for particle deposition through bends (1986–2006).

InvestigatorsPui et al. [18]McFarland et al. [15]aPeters and Leith [16, 17]Sippola and Nazaroff [19, 20]c

Duct bends
Bend typeSmall tubeSmall tubeIndustrial exhaust pipe ductIndoor rectangular ventilation duct
Deposition surface materialRound stainless steel and glass tube bendsRound wax tube bendsBend interior coated with petroleum jellyBare galvanized steel and internally insulated bends
OrientationHorizontal to downwards verticalNRdHorizontal to horizontal and horizontal to verticalUpwards vertical to horizontal and horizontal to downwards vertical
Construction techniqueNRdNRdSmooth, gored, and segmentedNRd
Hydraulic diameter, (cm)0.501 and 0.8511.615.2 and 20.315.2
Curvature ratio, (–)5.71–201.7–123.01
Bend angle, (deg)9045–13545, 90, 18090

Air flow
Reynolds numberb1, (×103)6 and 103.2–19.8203 and 36821.6–88.3
Bulk velocity, (m·s−1)18 and 317.7 and 18.620 and 27.12.2, 5.3, and 9.0 (8.8)

Particles
Aerosol type and material (density) (g/cm3)Monodisperse liquid oleic acid (0.89)Monodisperse liquid oleic acid (0.89)Polydisperse glass spheres (2.45)Monodisperse fluorescent particles (1.15)
Diameter, (μm)1.1–6.6105–1501–16
Stokes number, (–)0.03–1.350.07–0.70.08–160.00013–0.081
Reynolds numberb2, (–)1.3–12.70.05–1.510–200NRd
Dimensionless relaxation time, (–)0.4–270.4–23NRd0.0046–12

CommentsAssumption of no particle reboundingAssumption of no particle reboundingNo particle rebounding using petroleum jellySystem method to reduce the effect of particle rebounding

aOnly experimental data [15]; b1Reynolds number: ; b2particle Reynolds number: ; cbend 6 in [20] is not included, and bend 5 is the downstream half of a 180° quasi-bend; dNR: not reported.