EEG WaterCoanda Screens

Coanda ScreensCoanda Screens• Inclined screens that use overflowing water to stay clean• Tough screens with very low maintenance• Clean water falls through; fish & debris pass over

Coanda Screens

Coanda screens are tilted profile wire bar screens. The shape of the screens allows the screens to remain clean with little or no mechanical cleaning. The operation is enhanced by the Coanda Effect as the screens catch only the bottom layer of water. The tilted profile wires of the Coanda Screen slice off thin layers of water, allowing debris and fish to pass safely over the screen as water falls through the screen.

Coanda Screens Value Proposition

Simplify the intake with Coanda Intake design

Cost Item Typical Savings

Desilting structure Cap-Ex 10%

Desilting structure excess flow 5%

Coanda operating cost 5%

Eliminate the Desander

Coanda Screen Performance Testing

Key Results:• Defined adjustments for full

scale• Determined impact of flow in

excess of design• Determine impact of high

debris

US Bureau of Reclamation Testing

Key Results:• Developed

governing equation

• Determined impact of various parametersCSU

Testing:• Tested one

meter of screen for flow, cavitation, and debris

Debris laden water over a 2mm screen

Debris over the toe

Fine debris through the

screen

Overflow Debris Testing

Design Guidance: Coanda Screens

Head

at

Zero Bypass Case

Bypass Flow

Gross Head for Intake

Θ

Design Guidance: Coanda Screens

3 Decisions:• Accelerator Size and

Shape• Screen Slot Width• Design Loading

Design Guidance: Coanda Screens

3 Decisions:• Accelerator Size and

Shape• Screen Slot Width• Design Loading

Finer

Safety

Factor

Coanda Screens: Debris Passage

Fixed frame rib designed for extreme condition

Replaceable Screen Panel. Design case considerations below

Cost of stainless steel to

withstand extreme

design case

Cost of mobilization, material, and

supply for more

frequent repairs

3 Decisions:• Accelerator Size and

Shape• Screen Slot Width• Design Loading

Coanda Screens: Debris Passage

The boulders and logs pictured here passed over the screen without reducing flow or damaging the screen.