Shanghai up Pa Ventilation Equipment Co., Ltd
The flow rate of the fan refers to the volume of gas flowing through the fan per unit time. Units are m3 / h, m3 / min, m3 / s. In the domestic ventilation habits with m3 / h, and the blower used to use m3 / min, but in the fan design and performance calculations are mostly used m3 / s.
It should be noted that the volume flow of the ventilator is the volume flow of the ventilator "inlet", since the pressure of the ventilator in the flow cross section is different and the volume flow through the flow cross section will be different The
The full pressure of the ventilator is defined as the difference between the total pressure on the outlet cross section of the ventilator and the total pressure on the inlet cross section.
The total pressure of the airflow at a point or a section is equal to the sum of the dynamic pressure and the static pressure at that point or the cross section.
3. Dynamic pressure
The dynamic pressure of the ventilator is defined as the pressure of the kinetic energy of the gas on the outlet section of the ventilator. Or: Dynamic pressure is the pressure required to accelerate the gas from zero speed to a certain speed.
The dynamic pressure is proportional to the kinetic energy of the airflow.
Dynamic pressure acts only on the direction of the airflow and is always positive.
Pd = 0.5 × ρV% * p2% * p% * b
Where Pd = dynamic pressure Pa
Ρ = gas density kg / m% * p3% * p% * b
V = speed m / s.
4. Static pressure
The static pressure of the ventilator is defined as the total pressure of the ventilator minus the dynamic pressure of the fan. In fact, static pressure is a point in the air or gas filled with a point of absolute pressure and atmospheric pressure of the pressure difference, the point pressure is higher than the atmospheric pressure is positive, lower than when the negative.
Static pressure can act on all directions of the gas, independent of the speed, is a measure of the potential in the gas.
Ps = P% * p% * pt% * b-Pd
Where Ps = static pressure Pa
Pt = full pressure Pa
Pd = dynamic pressure Pa
The speed of the fan is the rotation speed of the fan wheel per unit time, commonly known as the angular velocity, which is conventionally indicated by n, in revolutions per minute (r / min).
6. Shaft power
Fan power of the fan is the actual power required by the fan. It includes the internal power of the fan and the mechanical loss of the bearing and transmission.
The shaft power is also known as the input power of the fan, which is actually the output power of the motor.
7. Ventilator efficiency
(1) Full pressure internal efficiency of ventilator η% * p% * pin% * b
The total internal pressure efficiency of the ventilator η% * p% * pin% * b is equal to the ratio of the full pressure effective power to the internal power of the ventilator.
(2) Static pressure internal efficiency of the fan η% * p% * ps.in% * b
The static pressure internal efficiency of the ventilator η% * p% * ps.in% * b is equal to the ratio of the effective power of the hydrostatic pressure to the internal power.
The full pressure internal efficiency of the ventilator and the static pressure internal efficiency of the ventilator are important parameters that characterize the aerodynamic performance of the fan.
(3) Full pressure efficiency of ventilator η% * p% * ptf% * b
The full pressure efficiency of the ventilator η% * p% * ptf% * b is equal to the ratio of the full pressure effective power to the shaft power of the fan.
(4) Fan static pressure efficiency η% * p% * psf% * b
Ventilator static pressure efficiency η% * p% * psf% * b is equal to the fan static pressure effective power and shaft power ratio.
8. Closed static pressure (BTSP)
Ventilator closed static pressure refers to the ventilator outlet is completely closed without gas movement when the static pressure.
9. Ventilator Full Exposure Gas Flow (WOCMS)
Ventilator full open gas flow is also known as open CMS (WOCMS), that is, the fan is fully open when the flow of operation. At this time the fan static pressure is zero.
10. Application scope
The fan operating flow and pressure range, as determined by the fan manufacturer, with satisfactory results when the fan is running.
Typical fan range of applications:
Front bend centrifugal fan: 30% -80% WOCMS
Posterior centrifugal fan: 40% -85% WOCMS
Radial centrifugal fan: 35% -80% WOCMS