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Hazen-Williams Head Loss Calculator

Compute head loss h_f = 10.67*L*Q^1.852/(C^1.852*D^4.87) from flow, pipe length, roughness coefficient C and diameter (SI units).

📐 计算公式

Hazen-Williams 沿程水头损失（本页代码口径）：h_f=10.67×L×Q^1.852÷(C^1.852×D^4.87)（m，Q 流量 m³/s、L 管长 m、C 粗糙系数、D 管径 m）。联动量：无其它派生项，结果保留 3 位小数。校验：四字段经输入守卫必填且须为合法数值，否则提示并中止。判据：无固定分级，h_f 与流量 1.852 次方成正比、与管径 4.87 次方成反比、与管长线性相关。

由流量、管长、粗糙系数 C 与管径，按 h_f = 10.67·L·Q^1.852/(C^1.852·D^4.87) 计算水头损失（SI）。

流量 Q (m³/s)

管长 L (m)

粗糙系数 C

管径 D (m)

📌 计算说明

适用于水温约 4–25℃ 的给水管道；C 值：新钢管≈120–140，旧管≈80–100。
单位为 SI（Q: m³/s，D: m，结果 m）。

📐 Hazen-Williams Reference

Constants and standards used on this page with their authoritative sources, for verification and citation.

Quantity	Value	Unit	Source
SI constant	10.67	(Q in m³/s, D and L in m)	SI form of the Williams & Hazen (1920) hydraulic tables
US customary constant	4.727	(Q in ft³/s, d in ft)	Williams & Hazen (1920) / AWWA practice manuals
Flow / diameter exponents	1.852 / 4.87	dimensionless	Empirical exponents of the Hazen-Williams fit
Roughness C (new steel / old cast iron)	130–140 / 100–110	dimensionless	Engineering experience values from water-supply design manuals and AWWA handbooks; no internationally standardised value
Applicability	Clean water near 20 °C, v ≲ 3 m/s, D ≳ 50 mm	—	Accepted range of the Hazen-Williams empirical formula

Note: Hazen-Williams has no Reynolds-number correction; errors can exceed 20% once temperature or viscosity departs markedly from 20 °C water. Use Darcy-Weisbach with the Colebrook equation in those cases.

📚 深度解析：海曾-威廉公式水头损失

💡 常见使用场景

给水管网按经验式估沿程损失。
不同 C 值（管材）对比能耗。
长距离配水校核末端压力。

标准算例

Q=0.01 m³/s、L=100 m、C=120、d=0.1 → h_f=10.67×100×0.01^1.852/(120^1.85×0.1^4.87)≈0.25 m。

C 值影响

C 从 120 降到 100（旧管），同条件损失增约 40%，结垢显著抬升能耗。

❓ 常见问题（FAQ）

C 是什么？: 海曾-威廉粗糙系数，新钢管 130~140、旧管或水泥管更低，材质越光滑越大。
和达西比？: 海曾为给水经验式，含 C 不直接显 f；达西更通用但需 f(Re,ε)。

Formula & Standard References

Item	Formula / Note	Source / Standard
Hazen-Williams equation	v = 0.849·C·R^0.63·i^0.54 (SI, R in m, i dimensionless)	Hazen & Williams 1905, AWWA
Applicability	Only for water in turbulent flow (Re ≈10⁴–2×10⁶), not gas or hot water	Water-supply design handbook
C value reference	PVC/PE 140–150, new cast iron 130, old steel 90–110 (declines with tuberculation)	Water-supply engineering tables
Versus Darcy	HW is convenient for hand calc but less fundamental than Darcy-Weisbach	Method-comparison literature

哈森-威廉姆斯水头损失计算器