Natural air blowing (EF = 0.5 ÷ ∞)

Interprogetti Genova has been always interested to find profitable applications of such a technique which was conceived and used by the masters from whom the senior members of the Interprogetti Genova staff learned the art of the ship design and who, with a lot of creativity and with the help of the slide rule, rebuilt a world devastated by two wars.
Air blowing naturally obtained through special devices that exploits the Bernoulli’s effect has been successfully used to solve various issues related to erosive bubble cavitation occurred on the blades of a number of fast naval ships and yachts. The remedy, in fact, was absolutely decisive (EF = ∞)

Taking into account the extraordinary damping effects that air bubbles have proven to have against erosive cavitation, Interprogetti Genova has undertaken a series of investigations, including tests on models and ships in full scale, to use such a technique for the purpose of reducing vibrations on the hull of the ship due to the pressure pulses induced by the propeller blades.

Regretfully, despite the satisfactory results observed during sea trials carried out on a large passenger ship which was provided with an air lubrication system (in this case mechanical and not natural air blowing was used), where either the wanted reduction of drag (EF abt. 1.05) and the vibration damping effect (EF abt. 1.3) where observed, the results achieved with models of ships purposely carried out to assess the effectiveness of the system on a small tanker were unsatisfactory (EF < 0.5) and showed that further attention is to be addressed to improve the design of the air blowing devices, to increase the Bernoulli’s effect and to better spread the parts to be protected.