1752, Swiss physicist Bernoulli first reported that the propeller was superior to all kinds of propellers that existed before it. He designed a double-lead screw propeller, which was installed in front of the stern rudder. 1764, the Swiss mathematician Euler studied other propellers that could replace sails, such as paddlewheels. Water spray, including propeller.
Submersibles and submarines move underwater, so traditional paddles and sails can't be used, and heavy paddles and wheels can't adapt. So the first manual propeller was not used on a ship, but as a propulsion tool for a submersible.
The appearance of steam engine provides a new good power for ship propeller, conforms to the development of steam engine and becomes the latest subject of ship propulsion.
The first experimental propeller was driven by Stephen, an American. He built a 7.6-meter-long ship at 1804, which was directly driven by a steam engine. He made his first experimental voyage on the Hudson River. It was found in the experiment that the engine didn't work, so he replaced it with a Watt steam engine. The experimental speed is 4 knots, and the highest speed reaches 8 knots.
Stephen's propeller has four windmill blades and is forged. Compared with ordinary windmills, it increases the radial width of blades. In order to choose a better pitch and speed matching in the experiment, the blade is made into an adjustable pitch structure. During the two-week experimental voyage on the Hudson River, the propeller changed several pitch values, but the experimental results were not ideal, and its performance was far inferior to that of the paddle wheel. This experiment made him understand that under the condition of low speed of steam engine, the advantages of open wheel have been fully exerted, and its propulsion efficiency is higher than that of propeller, which is an inevitable conclusion.
The introduction of archimedean spiral was first seen in 1803, and the British Archimedes propeller was patented in 1829. On this basis, 1840- 184 1 built some civil propellers. 1843, the British navy replaced the paddle wheel with a propeller for the first time on the "Rettler". Later, Smith designed 20 propeller ships and took part in the war against Russia. Smith became a famous figure.
1843, the U.S navy built the first propeller ship "Prin Sidon", which was designed by Captain Ellison. With the active promotion of Ellison, the United States continues to build 4 1 civilian propeller ships with a maximum displacement of 2,000 tons.
Although Britain, the United States and other countries have achieved some success, there are still many problems when propellers are used for ship propulsion, such as terrible vibration on wooden hull ships, propeller shaft bearing wear below the waterline, propeller shaft seal, thrust bearing and so on.
With the progress of technology, the above shortcomings of propellers have been overcome one by one, the speed of steam engines has also increased, and more and more propellers have replaced the paddles on board. By 1858, great eastern was equipped with the largest propeller in the world at that time, with a diameter of 7.3 meters, a weight of 36 tons and a rotation speed of 50 rpm. At that time, the propeller standard was no longer authoritative. Because the propeller's propulsion efficiency is close to that of paddle wheel, and there are many advantages that paddle wheel can't compete with, paddle wheel gradually disappears on the seagoing ship.
In the development of science and technology, the performance of many mechanical devices has been widely used when people are still unclear. However, it is difficult for these devices to achieve their best performance until people fully understand their physical laws and complete theoretical analysis. Propeller is no exception, until 1860, although it has become a leader in seagoing ships, its achievements are based on years of experience accumulation. The progress of propeller can no longer meet the needs of the development of ship technology only by relying on the intuitive reasoning of experts, and scientists need to make a complete explanation of its hydrodynamic characteristics, which promotes the development of propeller theory.
In the development of ship technology, the theoretical research of propeller is much more than any other professional field, from empirical method to digital design, and then to the optimization of propeller design by computer technology. The design of a good propeller is very important, and model test also plays a major role.