免费水头损失计算器
计算管道系统中的摩擦和局部水头损失。
Friction Head Loss
4.08 m
Friction Head Loss vs Darcy Friction Factor (f)
公式
## Darcy-Weisbach Head Loss Friction between the fluid and the pipe wall converts kinetic energy into heat, causing a pressure drop along the pipe. ### Formula **h_f = f (L/D) (V^2 / 2g)** where f is the Darcy friction factor (from Moody chart or Colebrook equation), L is pipe length, D is pipe diameter, V is flow velocity, and g is gravitational acceleration (9.81 m/s^2).
计算示例
Water at 2 m/s in a 100 mm pipe, 100 m long, with f = 0.02.
- 01D = 0.1 m
- 02V^2 / 2g = 4 / 19.62 = 0.2039 m
- 03h_f = 0.02 x (100/0.1) x 0.2039 = 0.02 x 1000 x 0.2039 = 4.08 m
- 04Pressure drop = 1000 x 9.81 x 4.08 / 1000 = 40.0 kPa
常见问题
How do I find the Darcy friction factor?
For turbulent flow, use the Moody chart or the Colebrook-White equation: 1/sqrt(f) = -2 log10(e/D/3.7 + 2.51/(Re sqrt(f))). For laminar flow (Re < 2300), f = 64/Re exactly.
What about losses from fittings and valves?
Minor losses from fittings are added separately: h_minor = K V^2/(2g), where K is a loss coefficient specific to each fitting type (elbow, tee, valve, etc.). The total head loss is the sum of pipe friction and minor losses.
Does pipe material affect head loss?
Yes, through the pipe roughness. New steel pipes have roughness e = 0.046 mm, PVC is 0.0015 mm, cast iron is 0.26 mm. Rougher pipes have higher friction factors and more head loss.
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