כיצד לחשב את Friction Loss
learn.whatIsHeading
Friction loss (pressure drop) in pipes and ducts represents energy loss. It's critical for pump and fan sizing.
נוסחה
Hazen-Williams: hf = (10.67×L×Q^1.85) / (C^1.85×D^4.87)
- L
- L value — Variable used in the calculation
- Q
- Q value — Variable used in the calculation
- C
- C value — Variable used in the calculation
- D
- D value — Variable used in the calculation
מדריך שלב אחר שלב
- 1Hazen-Williams: hf = (10.67×L×Q^1.85) / (C^1.85×D^4.87)
- 2Darcy-Weisbach: hf = f×(L/D)×(V²/2g)
- 3Results show required head or fan power
Worked Examples
קלט
PVC pipe (C=150), Q=0.05 m³/s, D=50 mm, L=100 m
תוצאה
hf ≈ 10-12 m head loss
Significant energy requirement
Common Mistakes to Avoid
- ✕Neglecting minor losses (fittings, valves)
- ✕Using wrong friction coefficients for pipe age
Frequently Asked Questions
How does diameter affect friction loss?
Loss inversely proportional to D^5 (or D^4.87); doubling diameter reduces loss 32×.
What is dynamic viscosity's role?
At low Reynolds numbers (laminar), viscosity dominates friction. At high (turbulent), roughness dominates.
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