Water tunnel (hydrodynamic)

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Cavitation tunnel of the Versuchsanstalt für Wasserbau und Schiffbau in Berlin

A water tunnel is an experimental facility used for testing the hydrodynamic behavior of submerged bodies in flowing water. It is very similar to a recirculating wind tunnel but with water as the working fluid, and related phenomena are investigated, such as measuring the forces on scale models of submarines or lift and drag on hydrofoils. Additionally, many water tunnels are sealed and can reduce the internal static pressure, to perform cavitation studies. These are referred to as cavitation tunnels.

Cavitating propeller model

1 Methods
2 List of Cavitation Tunnels (Water Tunnels)

[edit] Methods

Because it is a high-speed phenomenon, a special procedure is needed to visualize cavitation. The propeller, attached to a dynamometer, is placed in the inflow, and its thrust and torque is measured at different ratios of propeller speed (number of revolutions) to inflow velocity. A stroboscope synchronized with the propeller speed "freezes" the cavitation bubble. By this, one can observe if the propeller would be damaged by cavitation. To ensure similarity to the full-scale propeller, the pressure is lowered, and the gas content of the water is controlled.

Often, a tunnel will be co-located with other experimental facilities at a Ship model basin.