Cavitation tunnel
SSPA has over 50 years of experience in cavitation testing. The cavitation tunnel consist of three interchangeable measuring sections allowing high speed testing of propellers up to 23 m/s as well as large ship models of up to 10 meters in section number three. When performing cavitation studies for ships, the complete ship models can be installed in SSPAs cavitation tunnel, which provides a very good representation of the wake field.
Since the cavitation tunnel is a very cost-effective facility, there are many possibilities for solving any problems that might occur. In addition to cavitation studies and erosion prediction, the tunnel is used to measure pressure pulses and radiated noise. Tests can be performed for all kinds of vessels, including merchant ships and fast naval ships, as well as submarines and other underwater vehicles. In addition to study the ship propeller also energy saving devices, rudders, fins and PODs can be included in the scope.
The cavitation tunnel, with its three interchangeable sections, is also very valuable in various types of flow studies. Well correlated traditional methods are combined with high-speed video, PIV etc. Both in-house and external tools and programs are available to analyze the results.
The cavitation tunnel can also be used for studying and developing the latest green technologies such as ships equipped with an air cavity, air lubrication of ship hulls and tidal water turbines.
Technical data
| Tunnel section | 1 | 2 | 3 |
| Length, metres | 2.5 | 9.6 | 8.0 |
| Test section, m2 | diam 1 m | 2.6 × 1.5 | 2.1 × 1.22 |
| Max speed, m/sec | 23 | 6.9 | 9.9 |
| Min cav number | 0.06* | 1.45** | 0.30** |
* Empty tunnel
** With the propeller in a position 0.2 m below the ceiling
Hydrodynamics for submarines
Developing the hydrodynamics for submarines at SSPA involves a combination of simulation and model testing in order to evaluate the performance of the submarine, such as speed-power requirements, manoeuvring characteristics, cavitation properties and radiated noise from the propellers in deeply submerged, periscope and surface conditions.
The never ending battle with propeller cavitation
Even though propeller cavitation and its downsides, e.g. noise, vibration and erosion, could be suppressed in many cases for a conventional propeller, the absence of cavitation indicates that the design could be pushed further to gain higher efficiency and performance. This means that where high efficiency and performance are required, cavitation is unavoidable, which calls for silky skills at the design stage to manage the downsides of cavitation.