Hydraulic Jump in a Control Meter

Explanation:

A hydraulic jump is a phenomenon that occurs when there is a sudden change in the flow regime of a fluid. It typically occurs when a fast-moving, supercritical flow transitions to a slower, subcritical flow. In the context of a control meter, a hydraulic jump can be formed above the control.

Control Meter:
A control meter is a device used in hydraulic systems to regulate and measure the flow of fluid. It consists of a constriction or narrowing in the flow path, which causes a change in the flow regime.

Critical Depth:
Critical depth is a term used to describe the depth of flow at which the specific energy of the fluid is minimum. It is the depth at which the flow changes from subcritical to supercritical or vice versa.

Formation of Hydraulic Jump above the Control:
A hydraulic jump in a control meter will be formed above the control when the depth of flow is less than the critical depth. This can be explained as follows:

1. Supercritical Flow: Upstream of the control, the flow is fast-moving and supercritical. The specific energy of the fluid is high, and the flow depth is less than the critical depth.

2. Constriction: As the flow passes through the control meter, there is a constriction or narrowing in the flow path. This causes the flow velocity to increase.

3. Transition to Subcritical Flow: Due to the increase in velocity, the flow undergoes a sudden transition from supercritical to subcritical. The specific energy decreases, and the flow depth increases.

4. Hydraulic Jump: Above the control, the flow depth is greater than the critical depth, and the specific energy is higher than the minimum value. This leads to the formation of a hydraulic jump.

5. Energy Dissipation: The hydraulic jump dissipates the excess energy of the flow by converting it into turbulence and heat. This helps to stabilize the flow and reduce its velocity.

Conclusion:
In a control meter, a hydraulic jump will be formed above the control if the depth of flow is less than the critical depth. This occurs when the fast-moving, supercritical flow transitions to a slower, subcritical flow after passing through the constriction in the control meter.