Head When End Contractions Is Suppressed Calculator

Formula Used:

\[ \text{Still Water Head} = \left( \frac{\text{Francis Discharge with Suppressed End}}{1.84 \times \text{Length of Weir Crest}} \right)^{2/3} \]

Still Water Head:

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1. What is the Head When End Contractions Is Suppressed?

The Still Water Head is the height of water that remains still over a weir when end contractions are suppressed. It is a crucial parameter in hydraulic engineering for measuring flow rates over weirs.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \text{Still Water Head} = \left( \frac{\text{Francis Discharge with Suppressed End}}{1.84 \times \text{Length of Weir Crest}} \right)^{2/3} \]

Where:

Francis Discharge with Suppressed End — Discharge of flow without the end contraction (m³/s)
Length of Weir Crest — Measurement or extent of Weir Crest from end to end (m)
1.84 — Empirical coefficient for the Francis formula

Explanation: This formula calculates the still water head based on the discharge and weir crest length, using the Francis formula with suppressed end contractions.

3. Importance of Still Water Head Calculation

Details: Accurate calculation of still water head is essential for designing weirs, spillways, and other hydraulic structures. It helps in determining flow characteristics and ensuring proper water management.

4. Using the Calculator

Tips: Enter the Francis Discharge with Suppressed End in cubic meters per second (m³/s) and the Length of Weir Crest in meters (m). Both values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of suppressing end contractions?
A: Suppressing end contractions eliminates the side effects that can reduce the effective length of the weir, leading to more accurate flow measurements.

Q2: When should this formula be used?
A: This formula is specifically used for weirs with suppressed end contractions, typically in controlled laboratory or engineering settings.

Q3: What are typical values for Francis Discharge?
A: Discharge values vary widely depending on the weir size and water flow, but typically range from 0.1 to 100 m³/s for most applications.

Q4: Are there limitations to this formula?
A: The formula assumes ideal conditions and may need adjustments for very high or low flow rates, or for weirs with unusual geometries.

Q5: How accurate is this calculation?
A: The calculation provides a good estimate for engineering purposes, but actual measurements may vary due to factors like water viscosity and weir surface conditions.