4.3 Three-Dimensional Pebble Flow
223
Fig. 4.36 The probability density distributions of pebble diffusion within pebble spindles on height
H = 5m (a), 3 m (b), 2m (a) and 1 m (d) in the beds of base angles θ = 30 ◦ , 45 ◦ and 60 ◦
(about above H = 2 m) of the bed are almost consistent entirely with each other. In
Fig. 4.37b, the fitted velocity profiles are almost in perfect accordance with each other
too. This phenomenon confirms the feature of almost uniform pebble flow within the
cylindrical body. In contrast, in the conical base, the velocity profiles are different.
The pebble velocity near the bed center is far higher than that near the wall.
On the other hand, Fig. 4.38, compares the velocities of No. 25 (in the bed center)
and the No. 28 (on the wall) within the beds with the base angle θ = 30
◦
, 45
◦ , and
60
◦ . It is shown that the effects of the base angle also have few effects on the pebble
velocity within the common cylindrical body (about H ≥ 4m) of the beds. However,
as shown by quantified and fitted velocities, the pebbles in the bed of large base angle
(e.g., θ = 60
◦ ) may have higher velocity in the conical base part of the bed than that
of small base angles. By Fig. 4.37 and Fig. 4.38, the pebble flow within the HTR-PM
is predicted to be perfect uniform, which is a good feature for stabilization of the
reactor.
223
Fig. 4.36 The probability density distributions of pebble diffusion within pebble spindles on height
H = 5m (a), 3 m (b), 2m (a) and 1 m (d) in the beds of base angles θ = 30 ◦ , 45 ◦ and 60 ◦
(about above H = 2 m) of the bed are almost consistent entirely with each other. In
Fig. 4.37b, the fitted velocity profiles are almost in perfect accordance with each other
too. This phenomenon confirms the feature of almost uniform pebble flow within the
cylindrical body. In contrast, in the conical base, the velocity profiles are different.
The pebble velocity near the bed center is far higher than that near the wall.
On the other hand, Fig. 4.38, compares the velocities of No. 25 (in the bed center)
and the No. 28 (on the wall) within the beds with the base angle θ = 30
◦
, 45
◦ , and
60
◦ . It is shown that the effects of the base angle also have few effects on the pebble
velocity within the common cylindrical body (about H ≥ 4m) of the beds. However,
as shown by quantified and fitted velocities, the pebbles in the bed of large base angle
(e.g., θ = 60
◦ ) may have higher velocity in the conical base part of the bed than that
of small base angles. By Fig. 4.37 and Fig. 4.38, the pebble flow within the HTR-PM
is predicted to be perfect uniform, which is a good feature for stabilization of the
reactor.