Experiment # 3

To Study flow characteristics over a hump or weir.

Objectives

1.  To study the variation in flow due to introduction of different types of humps or weirs in the flume. Flow Characteristics over Hump

Apparatus

1. S-6 Tilting laboratory flume with manometer, slope adjusting scale and flow arrangement.
2. Hook gauge (to measure depth of water)
3. Broad crested weirs. a) Round corners b) Sharp corners. Flow Characteristics over Hump

Related Theory

Hump

It is a structure or obstruction that is constructed across a river or stream to raise the level of water on upstream side so that it can be diverted to canals to meet the irrigation requirements.

Flow Characteristics over Hump

Difference Between a weir and a barrage

If control gates are provided over weir its called a barrage. Flow Characteristics over Hump

Types of Flow

1. Critical Flow (FN = 1)
2.  Sub-Critical Flow (FN < 1)
3. Super-Critical Flow (FN > 1)

Effect of hump over depth of flow

Critical Hump Height

It is the minimum height of hump which causes the critical depth or critical flow conditions over the hump. Flow Characteristics over Hump

Effect of Hump Height Over Depth of Flow

Damming Action

If the hump height is made higher then the critical hump height, critical depth is maintained over the hump & depth, upstream of the is increased. This phenomena is known as Damming Action. Flow Characteristics over Hump

Procedure

1) Fix 1 particular value of slope
2) For 1 value of discharge maintain steady flow condition in flume.
3) Install round weir in the flume.
4) Measure the depth of flow at various locations.
5) Measure the horizontal distance at each section.
6) Repeat the same procedure for various discharges.
7) Repeat the same procedure for sharp corners weir.
6) Plot the water surface profiles. Flow Characteristics over Hump

 Observations & Calculations