The clinging condition finished at Ht′/P′ ∼ 0.07 for α = 6, 8, 12, and 20° and at Ht′/P′ ∼ 0.06 for α = 10°, 15°. The compound labyrinth weir with α = 35° was observed to change directly to an aerated or partially aerated nappe condition. The nappe aeration condition was observed when 0.12 < Ht′/P′ < 0.22 for α = 35°. Depending on α, the largest range of aeration nappe was observed for α = 6–20°. The nappe condition changes from aerated to partially aerated at 0.23 ≤ Ht′/P′ ≤ 0.43 for α = 6°. Depending on α, the largest range of partially aerated nappe was observed for α = 8–35°. The nappe drowned condition was observed when Ht′/P′ > 0.43 for α = 6°. Also, when α increased, the nappe drowned condition increased. The range of Ht′/P′ observed for each nappe aeration condition of compound labyrinth weirs is shown in Table 5. This table will assist the designer to avoid using undesirable ranges of Ht′/P′ in the design process.
Nappe aeration conditions for ranges of Ht′/P′ of compound labyrinth weirs with a quarter-round crest
| (Ht′/P′) . | ||||
|---|---|---|---|---|
| α (°) . | Clinging . | Aerated . | Partially aerated . | Drowned . |
| 6 | <0.073 | 0.073–0.23 | 0.23–0.43 | >0.43 |
| 8 | <0.067 | 0.067–0.31 | 0.31–0.48 | >0.48 |
| 10 | <0.064 | 0.064–0.32 | 0.32–0.5 | >0.5 |
| 12 | <0.074 | 0.074–0.29 | 0.29–0.54 | >0.54 |
| 15 | <0.06 | 0.06–0.28 | 0.28–0.58 | >0.58 |
| 20 | <0.07 | 0.07–0.26 | 0.26–0.60 | >0.60 |
| 35 | – | 0.12–0.22 | 0.22–0.62 | >0.62 |
| (Ht′/P′) . | ||||
|---|---|---|---|---|
| α (°) . | Clinging . | Aerated . | Partially aerated . | Drowned . |
| 6 | <0.073 | 0.073–0.23 | 0.23–0.43 | >0.43 |
| 8 | <0.067 | 0.067–0.31 | 0.31–0.48 | >0.48 |
| 10 | <0.064 | 0.064–0.32 | 0.32–0.5 | >0.5 |
| 12 | <0.074 | 0.074–0.29 | 0.29–0.54 | >0.54 |
| 15 | <0.06 | 0.06–0.28 | 0.28–0.58 | >0.58 |
| 20 | <0.07 | 0.07–0.26 | 0.26–0.60 | >0.60 |
| 35 | – | 0.12–0.22 | 0.22–0.62 | >0.62 |