Head Over Crest For Given Discharge Without Velocity Calculator

Formula Used:

\[ H = \left( \frac{Q \times 3}{2 \times C_d \times \sqrt{2 \times g} \times L} \right)^{\frac{2}{3}} \]

Francis Discharge with Suppressed End (Q):

m³/s

Coefficient of Discharge (C_d):

Acceleration due to Gravity (g):

m/s²

Length of Weir Crest (L):

Height of Water above Crest of Weir (H):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Head Over Crest Calculation?

The Head Over Crest calculation determines the height of water above the crest of a weir for a given discharge without considering velocity. This is essential in hydraulic engineering for designing and analyzing weir structures.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ H = \left( \frac{Q \times 3}{2 \times C_d \times \sqrt{2 \times g} \times L} \right)^{\frac{2}{3}} \]

Where:

\( H \) — Height of Water above Crest of Weir (m)
\( Q \) — Francis Discharge with Suppressed End (m³/s)
\( C_d \) — Coefficient of Discharge
\( g \) — Acceleration due to Gravity (m/s²)
\( L \) — Length of Weir Crest (m)

Explanation: This formula calculates the water height above the weir crest based on discharge rate, discharge coefficient, gravitational acceleration, and weir length.

3. Importance of Head Over Crest Calculation

Details: Accurate head calculation is crucial for proper weir design, flood control management, irrigation system planning, and hydraulic structure analysis.

4. Using the Calculator

Tips: Enter discharge in m³/s, coefficient of discharge, gravitational acceleration in m/s² (default 9.8), and weir length in meters. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is Francis Discharge with Suppressed End?
A: It's the discharge rate over a weir without end contractions, where the weir spans the full width of the channel.

Q2: What are typical values for Coefficient of Discharge?
A: For sharp-crested weirs, C_d typically ranges from 0.60 to 0.75, depending on weir geometry and flow conditions.

Q3: Why is gravitational acceleration important?
A: Gravity drives the flow over the weir, so accurate gravitational acceleration value is essential for precise calculations.

Q4: When should this formula be used?
A: This formula applies to suppressed weirs (no end contractions) with free flow conditions and negligible approach velocity.

Q5: What are the limitations of this calculation?
A: The formula assumes ideal conditions and may need adjustment for submerged weirs, significant approach velocity, or non-standard weir shapes.