PuK - Process Technology & Components 2024
A technical trade magazine with a history of more than 60 years.
A technical trade magazine with a history of more than 60 years.
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Vacuum technology<br />
Screw spindle vacuum pumps<br />
Fig. 5: Molecular scattering on a structured surface<br />
lows the diffuse wall model described generated at the beginning of each<br />
above. If a particle leaves the simulation<br />
area during the movement step, ary conditions. [Bir94]<br />
time step on the basis of the bound-<br />
it is eliminated from the simulation. The macroscopic variables such<br />
At the open edges, new particles are as pressure, temperature and flow<br />
velocity are then derived from the<br />
particle distribution with the respective<br />
particle masses, the momentum<br />
and the corresponding energy.<br />
Sazhin already used this method to<br />
investigate a pressure-driven flow,<br />
starting from a high-pressure reservoir<br />
with pressure p 1<br />
and temperature<br />
T 1<br />
through a channel with a triangular<br />
structure on the channel walls<br />
into a perfect vacuum (p 2<br />
= 0) [Saz20].<br />
An exemplary simulation domain<br />
is shown in Fig. 6. The channel<br />
width is considered to be much larger<br />
than the channel height, so that a<br />
2D flow is considered. The dash-dot<br />
line indicates a symmetry plane so<br />
that both edges have the same surface<br />
structure. Fig. 7 shows the mass<br />
flow through the channel with surface<br />
structures in relation to the mass<br />
flow that occurs with smooth walls at<br />
the same gap height as a function of<br />
the gap inlet pressure p 1<br />
for different<br />
profile angles α = β.<br />
More Than<br />
You Expect<br />
10 -3 hPa –<br />
10 -6 hPa<br />
10 -7 hPa –<br />
10 -13 hPa<br />
< 100 hPa<br />
1.013 hPa –<br />
10 -2 hPa<br />
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Pfeiffer Vacuum GmbH<br />
Germany<br />
T +49 6441 802-0<br />
www.pfeiffer-vacuum.com<br />
PROCESS TECHNOLOGY & COMPONENTS <strong>2024</strong><br />
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