How To Calculate Water Discharge

Orifice Discharge Equation:

\[ Q = C_d A \sqrt{2 g h} \]

Water Discharge (Q):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What Is Orifice Discharge?

Orifice discharge refers to the flow rate of water through an opening (orifice) in a tank or pipe. The discharge depends on the orifice size, shape, and the hydraulic head above the orifice.

2. How Does The Calculator Work?

The calculator uses the orifice discharge equation:

\[ Q = C_d A \sqrt{2 g h} \]

Where:

\( Q \) — Discharge rate (m³/s)
\( C_d \) — Discharge coefficient (unitless)
\( A \) — Cross-sectional area of orifice (m²)
\( g \) — Gravitational acceleration (9.81 m/s²)
\( h \) — Head above orifice center (m)

Explanation: The equation calculates the theoretical flow rate through an orifice, accounting for energy losses through the discharge coefficient.

3. Importance Of Discharge Calculation

Details: Accurate discharge calculation is essential for hydraulic engineering, water supply system design, irrigation planning, and environmental flow assessments.

4. Using The Calculator

Tips: Enter discharge coefficient (typically 0.6-0.8 for sharp-edged orifices), orifice area in square meters, and head in meters. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What Is A Typical Discharge Coefficient Value?
A: For sharp-edged circular orifices, C_d is typically 0.61-0.62. For well-rounded orifices, it can be 0.98-0.99.

Q2: How Does Orifice Shape Affect Discharge?
A: Different shapes have different discharge coefficients. Circular orifices are most common, but rectangular and other shapes require appropriate C_d values.

Q3: What Is The Difference Between Orifice And Weir Flow?
A: Orifice flow occurs through an opening, while weir flow occurs over a barrier. Different equations apply to each type of flow measurement.

Q4: When Is This Equation Not Accurate?
A: The equation assumes steady flow, constant head, and negligible approach velocity. It may be less accurate for very small orifices or rapidly changing conditions.

Q5: How To Measure Orifice Area Accurately?
A: Measure the diameter or dimensions precisely and calculate area using geometric formulas (πr² for circles, length×width for rectangles).