Page 24 - FANS. Aerodynamic _Selection Meethod__Combine_part2

A. Suction duct
All pressures are “correct”, incl. and static (depicted by the dotted
line). Ps suction. A line parallel to the abscissa axis is drawn, which

shows the value of Рatv suction. (i.e. part of the total pressure Pt
suction.), which goes to overcome the resistance of the atmosphere.
The rest of the total pressure (Рt suction) goes to overcome the
resistance of the ventilation network and is designated Pnw suction.

B. Delivery duct

Variants of static pressure on the fan nozzle Ps nag., As well as its change

along the length of the duct depend on various factors. And when a static
pressure is formed, it is possible to indicate the dynamic pressure Pd nag.
on the fan nozzle.

Some factors are shown in Fig.5:

1. High resistance of the discharge duct (air supply systems; exhaust

systems with flare exhaust; exhaust with an umbrella and high
capacity; low speed of exit from the fan nozzle - low productivity ...).
2. Low resistance of the discharge duct (exhaust systems; short duct;
high speed of the air outlet from the fan nozzle - high performance
...).
3. Low resistance of the discharge duct (short duct; very high speed of
the air outlet from the fan nozzle - high performance ...).

Additionally, parallel to the abscissa, a line is drawn that indicates the value
of Patv nag. (i.e. part of the total pressure Рt nagn.), which goes to
overcome the resistance of the atmosphere. The rest of the total pressure
(Рt nagn.) Goes to overcome the resistance of the ventilation network and
is designated as Pnw nag .