Page 12 - FANS. Aerodynamic _Selection Meethod__Combine_part2

Thus, the real drop in total pressure in the ventilation network Pnw = “f-e”
will differ from Ps = “h-e” (according to the current terminology) in a larger
direction, since the atmospheric resistance curve Рatv always passes below

the dynamic pressure curve Рv (according to the old terminology).

Now there is a complete picture of the new components of the total
pressure Pt and the possible variants of the dynamic pressure Pv (according
to the old terminology).

The above is confirmed by instrumental measurements (tests of random
fans without ductwork) and, for example, the following pressure ratio
results are obtained:

A. LOW PRESSURE FAN

a) in cross section of the suction inlet

 total (total pressure) - 1
 static (static pressure) - 20
 dynamic (dynamic pressure) - 19

b) in the cross section of the discharge pipe

 full (total) - 14
 static (static) - minus 4
 dynamic (dynamic) - 18

c) total pressure for the aerodynamic characteristics of the fan (in current
terminology)

 full (total) PT - 15
 static (static) Ps - minus 3 (1 - 4 = -3)

 dynamic (dynamic) Pv - 18

The dynamic pressure Pv of the fan is greater than its total pressure Pt.

B. MEDIUM PRESSURE FAN

a) in cross section of the suction inlet

 full (total) - 2

 static (static) - 38
 dynamic (dynamic) – 36