Comparison of the resistance of Dongguan spiral duct
When we calculate the spiral duct, we usually cannot do without the four major factors of flow (air volume), unit friction resistance, Reynolds number and friction resistance coefficient.
In the calculation, the simplified Reynolds formula is Ro = vd / ν
Where v is the kinematic viscosity coefficient (m2 / s)
ν is the wind speed (m / s)
d is the inner diameter of the duct (m)
It can also be seen from this formula that when the kinematic viscosity coefficient and the tube diameter are constant, the larger the Reynolds number, the smaller the value of ν, and the smaller the power.
According to the experiments of the British scholar Renault, the generation of laminar and rate flow, the volume section size, characteristic velocity (average velocity) of the fluid flowing through it are related to the viscosity coefficient and density of the fluid, see the dimensionless quantity --- Ro is similar Rule number formula:
Ro = udP / U = ud / ν
In the formula:
Ro--is a dimensionless quantity (similar criterion number)
u--is the average flow rate.
d-- is the characteristic size.
P--is the density of the liquid.
U-- is the viscosity coefficient of the liquid.
ν-- is the characteristic speed. Dongguan spiral duct is
based on the formula: We can verify similar criteria Ro for rectangular and elliptical tubes with a cross-sectional area of 1 square meter, assuming that the average flow velocity u of water flowing through this duct is 5m / s and the characteristic velocity ν is 1.13 × 10- 6m2 / s. The number of similarity criteria when the cross-sectional shape is rectangular is Ro1; the number of similarity criteria when the cross-sectional shape is oval is Ro2. Substituting known conditions into a dimensionless quantity formula