Experimental investigation of jet-induced resuspension of indoor deposited particles

Figures & data

Figure 1. The jet generation device in the test section: (a) schematics, and (b) picture.

Table 1. Measured roughness of particle-deposited plate surfaces.

Materials	PV (nm)	Rrms (nm)	Ra (nm)
Smooth glass (sg)	26.48	2.56	1.98
Rough glass (rg)	17,541.00	1729.00	1358.00
Smooth stainless steel (ss)	107.77	13.65	10.78
Rough stainless steel (rs)	5565.93	382.85	221.89

Figure 2. Pictures of the deposited dusts on the rough stainless steel plates photographed by a 3D super depth digital microscope in which the dark dots represent particles.

Table 2. Major parameters of the experiments.

Item	Value	Item	Value
Inner diameter of jet discharge tube, D	6.5 mm	Jet discharge duration	0.4 s
Jet discharge peak speed	20 m/s	Jet temperature	23.4°C
Ratio of the jet height to the inner diameter of the discharging tube, H/D	0.77, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60	Particle material	Arizona Test Dust, ATD
Particle bulk density	500 kg/m^3	Particle diameter	Less than 20.0 μm
Initially deposited surface dust load, ρs	0.46, 0.71, 1.44, 2.31, 2.98, 3.71, 4.78 g/m^2	Particle-laden substrate material	Glass and stainless steel with two different roughness values
Surrounding air temperature	22–24.5°C	Surrounding relative humidity	78–88%

Figure 3. Jet-induced dust cloud from a rough stainless steel plate with H/D = 5 and ρ_s = 4.78 g/m².

Figure 4. Pictures of the rough stainless steel plates with deposited dusts (ρ_s = 4.78 g/m², upper parts) and the normalized light intensity along the horizontal central lines (lower parts) after a jet impingement at different heights: (a) H/D = 5, and (b) H/D = 20.

Figure 5. Impingement jet plume and the generated wall shear stress: (a) a half-sectional view of a circular jet contour and the shear stress distribution, (b) variation of τ/τ_max with the horizontal distance from the stagnation point, and (c) variation of normalized τ_max with the jet height.

Figure 6. Variation of the dust-removal mass from a rough stainless steel plate with the jet impingement height: (a) with ρ_s = 1.44 g/m², removal mass normalized by 0.00339 g, and (b) with ρ_s = 4.78 g/m², normalized by 0.02169 g.

Figure 7. Variation of the total airborne particle numbers resuspended from the rough stainless steel plate with the jet impingement height; particles within the bin size of 1 to 3 μm refer to the left coordinate and other bin sizes to the right coordinate: (a) ρ_s = 1.44 g/m², and (b) ρ_s = 4.78 g/m².

Figure 8. Variation of the particle resuspension with the surface dust load after a jet impingement at H/D = 20: (a) dust-removal mass normalized by 0.01551 g, and (b) airborne particle numbers; particles within a bin size of 1 to 3 μm refer to the left coordinate and other bin sizes to the right coordinate.

Figure 9. Particle resuspension from different material surfaces: (a) dust-removal mass normalized by 0.00106 g, and (b) particle numbers; left coordinate for a bin size of 1 to 3 μm and right coordinate for other bin sizes.

Figure 10. Deposited dusts on the rough glass plate: (a) before a jet impingement, and (b) after a jet impingement.