1. What is the Coefficient of Discharge?

The Coefficient of Discharge (C_d) is a dimensionless number that represents the ratio of actual discharge to theoretical discharge in fluid flow through an orifice. For concrete orifices, it accounts for energy losses due to friction and flow contraction.

2. How Does the Calculator Work?

The calculator uses the Coefficient of Discharge equation:

Where:

• \( C_d \) — Coefficient of discharge (dimensionless)
• \( Q \) — Flow rate (m³/s)
• \( A \) — Orifice area (m²)
• \( g \) — Gravitational acceleration (9.81 m/s²)
• \( h \) — Head (m)

Explanation: The equation relates the actual flow rate to the theoretical maximum flow rate through an orifice, accounting for energy losses.

3. Importance of C_d Calculation

Details: The coefficient of discharge is crucial for designing hydraulic structures, calculating flow rates in irrigation systems, and analyzing water distribution networks.

4. Using the Calculator

Tips: Enter flow rate in m³/s, orifice area in m², and head in meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical C_d value for concrete orifices?
A: For concrete orifices, C_d typically ranges from 0.60 to 0.80, depending on the orifice geometry and surface roughness.

Q2: How does orifice shape affect C_d?
A: Sharp-edged orifices generally have lower C_d values (≈0.62) due to greater contraction, while rounded orifices approach 0.98.

Q3: Why is C_d always less than 1?
A: C_d accounts for energy losses (friction, turbulence) and vena contracta formation, making actual flow always less than theoretical.

Q4: How does surface roughness affect C_d for concrete?
A: Rougher concrete surfaces typically result in slightly lower C_d values due to increased friction losses.

Q5: Can this be used for submerged orifices?
A: This calculator is for free-flow conditions. Submerged orifices require different calculations accounting for downstream head.