Head When Coefficient Discharge Is Constant Calculator

Formula Used:

\[ \text{Height of Water above Crest of Weir} = \left( \frac{\text{Discharge through Triangular Weir}}{1.418} \right)^{2/5} \]

Height of Water above Crest of Weir:

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1. What is Head When Coefficient Discharge Is Constant?

The Head When Coefficient Discharge Is Constant refers to the height of water above the crest of a weir when the discharge coefficient remains constant. This is particularly relevant in triangular weirs where the relationship between discharge and head follows a specific mathematical formula.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \text{Height of Water above Crest of Weir} = \left( \frac{\text{Discharge through Triangular Weir}}{1.418} \right)^{2/5} \]

Where:

Discharge through Triangular Weir (Qtri) — Measured in cubic meters per second (m³/s)
1.418 — Constant coefficient for triangular weirs
2/5 — Exponent derived from the weir geometry

Explanation: This formula calculates the water height above the weir crest based on the discharge rate, assuming a constant discharge coefficient typical for triangular weirs.

3. Importance of Head Calculation

Details: Accurate head calculation is essential for designing and operating weirs in hydraulic systems, ensuring proper water flow measurement, and maintaining efficient water management in irrigation, drainage, and water supply systems.

4. Using the Calculator

Tips: Enter the discharge through the triangular weir in m³/s. The value must be greater than zero. The calculator will compute the corresponding head height above the weir crest.

5. Frequently Asked Questions (FAQ)

Q1: What is a triangular weir?
A: A triangular weir is a type of flow measurement device with a V-shaped notch used to measure open channel flow rates.

Q2: Why is the coefficient 1.418 used?
A: This coefficient is derived from empirical studies and represents the discharge coefficient for standard triangular weirs under specific conditions.

Q3: What are typical applications of triangular weirs?
A: Triangular weirs are commonly used in irrigation systems, wastewater treatment plants, and hydraulic laboratories for flow measurement.

Q4: How accurate is this calculation?
A: The calculation provides a theoretical value based on the formula. Actual measurements may vary due to factors like weir condition, water temperature, and approach conditions.

Q5: Can this formula be used for other weir types?
A: No, this specific formula is designed for triangular weirs. Other weir types (rectangular, trapezoidal) have different formulas and coefficients.