Turbulence characteristics in the approach flow of Piano Key Weir (PKW)

English Abstract:

Dams whose fail could cause loss of life or enormous assets injure are painstaking to survive a probable maximum flood (PMF), but the PMF in various locations has been amplified at regular intervals, resulting in spillways that no longer convene the proposed norms. Spillway rehabilitation is required for lots of dams in India; in order to get better hydraulic competence. Catastrophe in Uttarakhand & Jammu-Kashmir (June 2013 & August 2014) necessitates the research aspect of spillway rehabilitation. In recent years, a novel idea of Labyrinth weirs has been developed by means of a new shape, called Piano Key Weir. Piano Key Weir (PKW) is an innovative alternative of non-linear (labyrinth type) weirs that has a higher discharge capacity with a relatively smaller footprint. This alternative of Labyrinth weir provides an increase in the steadiness of the structure which can be positioned on the top of most existing or new diversion or storage dam structures. The PKW has a rectangular nonlinear weir crest layout (in planform), unlike traditional labyrinth weirs, the sloped floor in the inlet and outletcycles, referred to as keys, overhangs the apexes providing a longer crest length than a rectangular labyrinth weir, and several times to the transverse weir width. The Piano Key Weir doesn't have any gates. So it will involve very little operation & maintenance and would be very much cheaper than conventional dam spillways or barrage structure. Since in mountainous river of India, use of PKW may be promoted by answering the question of sedimentation behind it. As sediment from upstream normally moves downstream by flowing water, geographical features are changed and hydro-ecological habitats are subsequently affected. To support recovery of sediment continuity in rivers, the Piano Key Weir might be used as an alternative transverse structure. It needs the elemental sediment transport study in the approach flow PKW to point out the physical hydraulic characteristics. Since the sediment transport is linked with turbulence present in flow. This paper presents the experimental observations of the first and second order velocity profiles in piano key weir approach flow. Different turbulence characteristics including turbulent kinetic energy & turbulence intensity is also discussed in the paper.