Flow Over Notches (Accessory)

Note: Price is based on given specs. For other specifications, please submit an inquiry.

Flow Over Notches is an important experimental setup used in fluid mechanics and hydraulics laboratories to measure the rate of flow of water in open channels. A notch is a sharp-edged opening provided in a vertical plate, placed perpendicular to the direction of flow. The Flow Over Notches apparatus helps students understand the relationship between head of water and discharge.

This experiment is widely included in civil engineering, mechanical engineering, and hydraulic engineering curricula. It plays a crucial role in understanding open channel flow behavior and discharge measurement methods used in irrigation channels, dams, and water supply systems.

What is a Notch?

A notch is a calibrated opening in a thin plate installed in the side of a tank or channel. Water flows over the notch, and the discharge is calculated by measuring the height of water (head) above the crest of the notch.

Common types of notches used in laboratories include:

• Rectangular Notch

• V-Notch (Triangular Notch)

• Trapezoidal Notch (Cipolletti Notch)

Each type has its own discharge equation and practical applications.

Principle of Flow Over Notches

The Flow Over Notches experiment is based on the principles of:

• Continuity

• Bernoulli’s theorem

• Energy conservation in open channel flow

When water flows over a sharp-edged notch, the velocity of flow depends on the head of water above the crest. The discharge is proportional to the head raised to a specific power, depending on the notch shape.

General Discharge Equation

$$Q = C_d \times \text{Theoretical Discharge}$$

Where:

• $Q$ = Actual discharge

• $C_d$ = Coefficient of discharge

This experiment helps determine the coefficient of discharge for different notches.

Types of Notches Used in the Apparatus

1. Rectangular Notch

Used for measuring large flow rates. The discharge depends on the width of the notch and the head of water.

2. V-Notch (Triangular Notch)

Highly sensitive to small flow rates. Commonly used for precise discharge measurement.

3. Cipolletti Notch

A trapezoidal notch designed to eliminate end contraction losses.

The Flow Over Notches apparatus generally includes interchangeable notch plates for performing multiple experiments.

Construction of Flow Over Notches Apparatus

A standard Flow Over Notches (Accessory) consists of the following components:

1. Notch Tank

A rectangular tank made of mild steel or transparent acrylic to observe flow behavior.

2. Notch Plates

Sharp-edged plates made of brass or stainless steel, precisely machined for accuracy.

3. Point Gauge

Used to measure the head of water above the crest of the notch accurately.

4. Water Supply System

Includes inlet piping, flow control valve, and drain arrangement.

5. Measuring Tank

Used to calculate actual discharge by the volumetric method.

6. Supporting Frame

A rigid frame ensures stability and proper alignment during experimentation.

The apparatus is compact, durable, and suitable for repeated laboratory use.

Working of Flow Over Notches Apparatus

The working procedure is simple and systematic:

1. Water is allowed to flow into the notch tank.

2. The flow rate is adjusted using the control valve.

3. Water flows steadily over the notch plate.

4. The height of water above the crest is measured using a point gauge.

5. The actual discharge is measured using a measuring tank and stopwatch.

6. Theoretical discharge is calculated using standard formulas.

7. The coefficient of discharge is determined.

8. The experiment is repeated for different heads.

This procedure helps students understand discharge variation with head.

Experimental Calculations

For different notches, discharge is calculated using standard equations:

Rectangular Notch

$$Q = \frac{2}{3} C_d b \sqrt{2g} H^{3/2}$$

V-Notch

$$Q = \frac{8}{15} C_d \sqrt{2g} \tan(\theta/2) H^{5/2}$$

Where:

• $b$ = Width of notch

• $H$ = Head of water

• $g$ = Acceleration due to gravity

These calculations reinforce theoretical learning with practical results.

Applications of Flow Over Notches

Educational Applications

• Fluid mechanics laboratories

• Civil engineering hydraulics labs

• Demonstration of open channel flow

• Discharge measurement experiments

• Determination of coefficient of discharge

Practical Applications

• Irrigation channels

• Water supply systems

• Dams and reservoirs

• Wastewater treatment plants

• Canal flow measurement

Flow over notches is widely used where accurate discharge measurement is required.

Advantages of Flow Over Notches Apparatus

• Simple construction and operation

• High accuracy in discharge measurement

• Suitable for small and medium flow rates

• Easy observation of flow pattern

• Cost-effective laboratory equipment

• Helps in clear understanding of open channel flow

• Reliable and repeatable results

These advantages make it a preferred choice in engineering institutions.

Limitations of Notches

• Not suitable for very large flow rates

• Requires steady and uniform flow

• Sensitive to upstream disturbances

• Head measurement must be accurate

Despite these limitations, notches are extremely effective for laboratory experiments.

Importance in Engineering Education

The Flow Over Notches experiment helps students:

• Understand open channel hydraulics

• Correlate theory with practical observations

• Learn discharge calculation techniques

• Analyze experimental errors

• Build strong fundamentals in fluid mechanics

It forms the foundation for advanced studies in irrigation engineering and hydraulic structures.

Quality and Laboratory Standards

A high-quality Flow Over Notches apparatus is manufactured using precision-machined notch plates and corrosion-resistant materials. Accurate point gauges and leak-proof construction ensure consistent performance.

Well-designed accessories meet standard laboratory requirements and provide long service life with minimal maintenance.