Total Head For Actual Discharge Over Broad Crested Weir Calculator

Formula Used:

\[ H = \left(\left(\frac{Qa}{Cd \cdot Lw \cdot hc}\right)^2 \cdot \frac{1}{2 \cdot g}\right) + hc \]

Actual Discharge (Qa):

m³/s

Coefficient of Discharge (Cd):

Length of Weir Crest (Lw):

Critical Depth (hc):

Acceleration due to Gravity (g):

m/s²

Total Head (H):

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1. What is Total Head for Actual Discharge Over Broad Crested Weir?

Total Head for Actual Discharge Over Broad Crested Weir is the combination of weir crested and additional head. It represents the total energy head required for a specific discharge over a broad crested weir.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ H = \left(\left(\frac{Qa}{Cd \cdot Lw \cdot hc}\right)^2 \cdot \frac{1}{2 \cdot g}\right) + hc \]

Where:

\( H \) — Total Head (m)
\( Qa \) — Actual Discharge over Broad Crested Weir (m³/s)
\( Cd \) — Coefficient of Discharge
\( Lw \) — Length of Weir Crest (m)
\( hc \) — Critical Depth of Weir (m)
\( g \) — Acceleration due to Gravity (m/s²)

Explanation: The equation calculates the total head required for a given discharge by considering the velocity head component and adding it to the critical depth.

3. Importance of Total Head Calculation

Details: Accurate total head calculation is crucial for designing weir structures, determining flow characteristics, and ensuring proper hydraulic performance in open channel flow systems.

4. Using the Calculator

Tips: Enter actual discharge in m³/s, coefficient of discharge, length of weir crest in meters, critical depth in meters, and acceleration due to gravity in m/s². All values must be positive and valid.

5. Frequently Asked Questions (FAQ)

Q1: What is a broad crested weir?
A: A broad crested weir is a hydraulic structure with a wide, horizontal crest that allows water to flow over it, used for flow measurement and control in open channels.

Q2: How is coefficient of discharge determined?
A: The coefficient of discharge is typically determined experimentally and depends on the weir geometry, approach conditions, and flow characteristics.

Q3: What is critical depth in weir flow?
A: Critical depth is the depth of flow where energy is at a minimum for a particular discharge, occurring when the Froude number equals 1.

Q4: When is this formula applicable?
A: This formula is applicable for free-flow conditions over broad crested weirs where the flow is critical over the weir crest.

Q5: What are typical values for coefficient of discharge?
A: For broad crested weirs, the coefficient of discharge typically ranges from 0.3 to 0.6, depending on the weir shape and flow conditions.