Tangential Vortex Intake Video

Video clips of typical Tangential Vortex Intake designs examples are shown. The examples include both stable and unstable designs. The detailed geometry of tangential vortex intake models are also provided together with the predicted and observed control shift discharge and free drainage discharge.

1. Stable Intake (No. 6)

• D = 127 mm
• B = 98 mm
• e = 26 mm
• z = 94.2 mm
• β = 21.7°
• Qc = 3.2 L/s (observed Qc = 3.8 L/s)
• Qf = 6.3 L/s (observed Qf = 5.5 L/s)
• Qf / Qc = 1.94

• In this stable tangential vortex design, the flow in the intake is smooth for all discharges and drains freely into dropshaft without interference of swirling flow in the dropshaft. The control shift from the approach channel to the junction is observed at Q = 3.8 L/s.
• For Q < Qc, the uneven water surface distribution in the tapering section is found.
• The interference by the swirling flow in the dropshaft to the inflow at the junction is minimal even after the vortex flow level (after 360° turn) rises above the junction invert level at Q = 5.5 L/s.
• The air core in the dropshaft is found non-circular and eccentric.

2. Unstable Intake (No. 14)

• D = 73.5 mm
• B = 98 mm
• e = 17 mm
• z = 270.9 mm
• β = 35.1°
• Qc = 9.7 L/s (observed Qc = 6.0 L/s)
• Qf = 3.5 L/s (observed Qf = 1.3 L/s)
• Qf / Qc = 0.36

• The flow is draining freely only for the small discharge (up to Q = 1.2 L/s). At Q = 1.3 L/s (observed free drainage discharge), the flow at the junction begins to be unstable with fluctuating water surface in the dropshaft because of the interference of vortex flow in dropshaft with the inflow.
• When Q > Qf, the flow in the intake becomes unstable; an apparent hydraulic jump is seen in the intake. With the increase of discharge, the hydraulic jump becomes stronger and moves upstream until the whole flow in the tapering section becomes subcritical.
• Beyond the observed Qc, the entire approach channel flow becomes subcritical and the water surface is almost horizontal.