Experiment # 4

To Study flow characteristics of hydraulic jump developed in lab flume.

Objectives

1. To physically achieve the hydraulic jump in the lab flume.
2. To measure the physical dimensions of hydraulic jump.
3. To calculate the energy losses through hydraulic jump.
4. To plot water surface profiles for hydraulic jump at different discharges.

Apparatus

1. S-6 Tilting laboratory flume with manometer, slope adjusting scale and flow arrangement.
2. Hook gauge (to measure depth of water). Characteristics of Hydraulic Jump

Related Theory

Hydraulic Jump

The rise of water level which takes place due to transformation of super critical flow to sub critical flow is termed as hydraulic jump. Characteristics of Hydraulic Jump

Expressions for Depth of Hydraulic Depth

Expressions for Loss of Energy due to Hydraulic Jump

Length of Hydraulic Jump

The length between two sections where one section is taken just before the hydraulic jump and the other section is taken just after the hydraulic jump is termed as length of hydraulic jump.
For rectangular channels Length of hydraulic jump = 5 to 7 times the depth of hydraulic jump. Characteristics of Hydraulic Jump

Location of Hydraulic Jump

Depends on two things.
1) d2 = Depth of flow just after the hydraulic jump.
2) yc = Normal depth of flow at downstream. Characteristics of Hydraulic Jump

Types of Hydraulic Jump

1) FN1 = 1.0 (Critical)       No jump
2) FN1 = 1 to 1.7               Undular jump
3) FN1 = 1.7 to 2.5            Weak jump
4) FN1 = 2.5 to 4.5            Oscillating jump
5) FN1 = 4.5 to 9               Steady jump
6) FN1 = > 9                       Strong jump

Practical Applications of Hydraulic Jump

1. To dissipate the energy of water flowing over the hydraulic structures and thus prevent the scouring of downstream structure.
2. To recover the head or raise the water level on the downstream side of the hydraulic structure & thus to maintain high water level in the channel for irrigation or other water distribution purposes.
3. To increase the weight on apron & thus reduce the uplift pressure under the structure by raising the water depth on apron.
4. To mix the chemicals for water purification. Characteristics of Hydraulic Jump

Procedure

1. Fix one particular value of slope.
2. Set a particular discharge in the flume.
3. Develop the hydraulic jump
4. Measure the depth of flows. yo, y1, y2 & corresponding distances xo, x1, x2.
5. Repeat the procedure with varying discharges.
6. Plot the water surface profiles of hydraulic jump at different discharges.

Observations & Calculations

Comments

The Experiment has been performed successfully and the results have shown us that in last two values the fraud number is indicating oscillating type of Jump where as in the first three values the fraud number is indicating undular  type of jump. Characteristics of Hydraulic Jump,Characteristics of Hydraulic Jump, Characteristics of Hydraulic Jump, Characteristics of Hydraulic Jump, Characteristics of Hydraulic Jump, Characteristics of Hydraulic Jump