Filter
Top Products
TRG-TRC013-EN 37
period two
Fan Types
notes
The VPVA fan is selected so that the operating point is within the most efficient
area of the performance curves. Total efficiencies from 60 to 84 percent are
possible with the VPVA fan. Again, total efficiency is calculated by substituting
total pressure for static pressure in the static efficiency equation.
Like the BI, AF, and fixed-pitch vaneaxial fans, the input power lines are
essentially parallel to the blade pitch curves. Therefore, the VPVA fan is a
nonoverloading type of fan.
airflow
airflow
total pressure
total pressure
surge region
surge region
50%
50%
70%
70%
80%
80%
85%
85%
i
n
p
u
t
p
o
w
e
r
i
n
p
u
t
p
o
w
e
r
bl
ade
p
i
t
c
h
(
a
ngl
e)
bl
ade
pi
t
c
h
(
an
gl
e)
50º
50º
40º
40º
35º
35º
30º
30º
20º
20º
15º
15º
55º
55º
45º
45º
25º
25º
Figure 56