UNDERWATER SAIL
patrz http://www.youtube.com/watch?v=bNMW-jRoseo
Text for movie "underwater sail". Sailboats are beautiful, quiet and economical. The question is if a boat powered by the "underwater sail", presented in this film, can be equally beautiful, quiet and economical? - The beauty will depend on the designer. - The noise level will depend on method used to generate low-pressure air. - The fuel economy will depend on the overall drive efficiency. I'll discuss these three elements using as an example the presented model. I call it "O2". The main propulsion nozzle is located under the stern, and two nozzles located under the bow are working as bow thrusters. The main propulsion nozzle consists of a flexible tube, which supplies air under an oblique surface of the stern. Bow air-nozzles deliver air to oblique surfaces of the bow and effectively generate a side-directional thrust force. Main nozzle can be flexible or mobile, because it does not carry any force. Its task is to supply air at a given depth. Air bubbles fill space between nozzle and the stern surface, reduce the density of water and reduce static pressure. Water immediately moves into the "pressure hole". This creates a stream of water and air that flows upwards and strikes the oblique surface of the stern. During the impact there is momentum exchange . The drive efficiency depends on whether the impact is less or more elastic. I think it is too difficult to explain this process using the theory of collisions so it is much better to presume that a stream of water and air works as an "underwater wind" and the lower stern surface acts as an "underwater sail". Name "O2" is not accidental. Each kW (kilowatt) of installed power would inject into water 1,000 litres of air per minute. Therefore, driving such a boat would cause extremely effective water aeration, because the source supplying oxygen, would be moving. Manoeuvrability of such a boat would be great. It could easily perform turns and rotation, and supplying the air simultaneously to both bow nozzles would move the boat "in reverse". Powering such a boat with air is open to a whole range of possibilities. Compressed air and liquid air tanks, Roots blower driven by a Diesel engine or electric motor, compressors powered by liquid gas, or any chemical gas generators. All these methods of generating air do not create much noise; even a Diesel engine powering a Roots blower works at constant RPM and provides comfortable working conditions. The biggest advantage of a boat powered by "underwater sail" is the cost of installation. One source of air located anywhere on the ship can be used to provide the main propulsion, bow thrusters, and stern thrusters. Another very important advantage is that there are no rotating parts on the outside of the ship. This would allow navigation even in seaweed filled water. As far as the efficiency of the boat propelling system is concerned, this is an open case for now. To establish precisely this efficiency more comprehensive research is required. However, my preliminary studies and tests provide very optimistic results and suggest that the efficiency of the "underwater sail" propelling system can be near the efficiency level of the standard marine propeller after the optimization of the hull shape ( in areas interacting with the stream generated by the air-nozzles). |
