at the level of the needles holder. Once designed and machined
by Laporte, these deflectors were tested in situ with smoke and
turned out to perform very well, as predicted by the CFD analysis.
A third undesired situation addressed by CFD simulations is the
one caused by impinging flow on non-sterile surfaces: the accumulation table and the conveyor discs. In both cases, the parts
expose a horizontal surface directly to the vertical flow, inducing
stagnation points and undesirable vortices.
On the table at the beginning of the production line, opened
vials accumulate and form a circular pattern near the exterior
edge of the table. This table is designed with a central hole, allowing for a proportion of the impinging flow to evacuate without
touching the vials.
Nevertheless, some streamlines evacuate through the exterior
edge, passing through a series of vials. Many fixes to decrease
head losses for the flow through the central hole have been
tested in simulation with mixed success. The attention was then
focused on determining the actual risk of contamination for the
evacuation through the exterior edge, and a particular simulation
of the flow around the vials was performed. This detailed simula-
tion, with actual vials modeled, used the global simulation fields
to determine boundary conditions. It showed that in steady-
state, the entire flow in contact with the table would evacuate
through the vials’ shoulders, thus limiting the contamination
risks. Laporte also established a specific cleaning procedure for
the accumulation table.
As for the non-sterile conveyor discs, they would induce a
stagnation point surrounded by vortices that would eventually
transport particles over the vials path. Thus, their initial design
as solid discs was questioned and Laporte ultimately remanufactured the discs and added holes, allowing for a much better
evacuation towards the machine floor. The modification was tested with the CFD model and with smoke ejections - both methods
confirmed the suppression of the issue.
The project was a convincing demonstration of the reverse
engineering solutions and CFD capabilities of Creaform’s
Engineering Services team. The project was also a clear demonstration of the innovative mind of Laporte, who adopted CFD in
its cleanroom validation in order to gain predictive insight otherwise impossible to obtain using the traditional smoke tests.
The CFD results presented here are currently used in combination with the smoke test videos to demonstrate the effectiveness
of the aerodynamic barrier in front of regulatory agencies. So far,
the feedback is very positive as CFD really helps to visualize the
flow features. Creaform and Laporte hope to make CFD a prevalent
tool for future pharmaceutical production line flow validation.
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