7.5 Friction Optimization
485
Fig. 7.34 Distribution of vertical velocity in radial direction of different layers
MFI =
v wall
v centerline
(7.12)
Figure 7.34 compares the distribution of mean vertical velocity in the radial direction from 20s to 120 s in Fig. 7.33b and c cases. Horizontal layer-like regions with
5 cm height (25–30 cm, 65–70 cm, etc.) are selected, and then the mean vertical velocity of pebbles within each layer is calculated. MFI values of different layers have
been calculated and labeled in Fig. 7.34 as well.
Using MFI values as an indication of flow patterns, a pebble bed with μ p−w
= 0.1 presents typical mass flow, while the situation in the μ p−w = 0.3 case is a
485
Fig. 7.34 Distribution of vertical velocity in radial direction of different layers
MFI =
v wall
v centerline
(7.12)
Figure 7.34 compares the distribution of mean vertical velocity in the radial direction from 20s to 120 s in Fig. 7.33b and c cases. Horizontal layer-like regions with
5 cm height (25–30 cm, 65–70 cm, etc.) are selected, and then the mean vertical velocity of pebbles within each layer is calculated. MFI values of different layers have
been calculated and labeled in Fig. 7.34 as well.
Using MFI values as an indication of flow patterns, a pebble bed with μ p−w
= 0.1 presents typical mass flow, while the situation in the μ p−w = 0.3 case is a