Pr. Wormleaton et E. Soufiani, AERATION PERFORMANCE OF TRIANGULAR PLANFORM LABYRINTH WEIRS, Journal of environmental engineering, 124(8), 1998, pp. 709-719
A high level of dissolved oxygen is vital for the maintenance of healt
hy streams and rivers. Structures in rivers can increase dissolved oxy
gen levels by creating turbulent conditions where small air bubbles ar
e carried into the bulk of the flow. Plunging overfall jets from weirs
are a particular instance of this, and the aeration properties of suc
h structures have been studied widely in the laboratory and field over
a number of years. On the other hand, labyrinth weirs, where the weir
sill is cranked in planform thus increasing their length, have receiv
ed little or no attention in this context. They have a proven hydrauli
c advantage over straight weirs of increased discharge at the same hea
d for design conditions. However, they also serve to modify the combin
ed overfall jet as individual jets from adjacent sections of the weir
collide. This paper describes an experimental investigation into the n
ature of these jets and how they affect the aeration performance of a
triangular plan labyrinth weir. It is demonstrated that the aeration e
fficiency of these labyrinth weirs generally is better than their equi
valent-length linear weir and that this advantage becomes more pronoun
ced as the weir included angle becomes smaller and also at lower overf
all drop heights and higher discharges. These results point to the pos
sible advantage of these type of weir in situations where both hydraul
ic and aeration performance needs to be optimized.