Correct Answer - Option 4 : All of the above
Auxiliary devices:
Auxiliary devices such as chute blocks, sills, baffle walls, etc. These devices can help in dissipating the energy of flow by offering resistance to flow and may stabilise the flow in a shorter length of the basin, thus affecting economy.
Chute Blocks:
- Chute blocks are a kind of serrated device (e. row of small projections like teeth of saw) and provided at the entrance of the stilling basin.
- The incoming jet of water is furrowed and partly lifted from the floor, producing a shorter length of a jump than what would have been without them.
- They also help in stabilizing the flow and thus improve the jump performance
Sills and Dentated Sills:
- Dentated Sill or more preferably dentated sill is generally provided at the end of the stilling basin.
- The dentated sill diffuses the residual portion of the high-velocity jet reaching the end of the basin.
- They, therefore, help in dissipating residual energy and to reduce the length of the jump or the basin
Baffle Piers:
- They are the blocks placed within the basin, across the basin floor.
- They help in breaking the flow and dissipate energy mostly by impact.
- These baffle piers, sometimes called friction blocks, are very useful in small structures, such as low spillways and weirs, etc.
- They, however, give way due to cavitation, under the influence of high velocity jets, and hence are unsuitable for large works.
