The fan selection

                                                                    The fan selection

1, the standard state: refers to the air pressure at the inlet of the fan is P = 101325 pa, t = temperature 20 ℃, relative humidity phi = 50% of the gas state.

2, the specified state refers to being fan inlet condition. Including the local atmospheric pressure or the local altitude, imported gas pressure, the temperature of the gas and imported gas composition and volume percent concentration.

3, fan flow and flow coefficient

Traffic: refers to the unit time through the fan inlet gas volume.

Q, said units: often m3 / h or m3 / min.

Flow coefficient: phi = Q/(900 PI D22 * U2)

Type: phi: flow coefficient Q: traffic, m3 / h

D2: impeller diameter, m

U2: the impeller outer edge linear velocity, m/s (U2 = PI D2n / 60)

4, fan coefficient of total pressure and total pressure:

Fan: full pressure on fan exit total pressure and the difference between the total pressure on the import section. Expressed in PtF, commonly used units: Pa: total pressure coefficient bits of t = KpPtF/rho U22

Bits of t type: total pressure coefficient Kp: compressibility correction coefficient PtF: fan total pressure, Pa rho: inlet gas density, Kg/m ^ 3 u2: the impeller outer edge linear velocity, m/s

5, the wind pressure motor: fan exit characterized in the kinetic energy of the gas pressure, expressed in Pd. Commonly used units: Pa

6, static pressure fan: all reduce to dynamic pressure of the fan, fan with Pj said. Commonly used units: Pa

7, fan out the relationship between the total pressure, static pressure and dynamic pressure:

Fan of total pressure (PtF) = static pressure of the fan (Pj) + fan pressure (Pd)

8, fan inlet gas density, the density of the gas is refers to the mass of the gas unit volume, expressed with rho, commonly used units: Kg/m3

9, fan inlet gas density gauge formula: rho = P/RT

Type: P: inlet absolute pressure, P a R: gas constant, J/Kg · K. Related to the types of gas and the composition of the gas. T: import the kelvin temperature of the gas, K. And the relationship between the Celsius temperature: T = 273 + T

10, standard with a specified state conversion between main parameters:

Traffic: rho Q = rho 0 q0

The total pressure: PtF/rho PtF0 / rho = 0

Internal power: Ni/rho Ni0 / rho = 0

Note: the type of bottom marking "0" for the standard of state parameter, with no bottom target parameters for a given condition.

11, fan than speed calculation formula: Ns = 5.54 n Q01/2 / (KpPtF0) 3/4

Type: Ns: the specific speed of the fan, the important design parameters, similar to the specific speed of the fan are the same. N: fan spindle speed, r