Rollo's new full-rotation permanent magnet thruster trial

The Norwegian University of Science and Technology (NTNU) in Trondheim installed two of these propellers on its 31-meter-long scientific research vessel, the Gunnerus, and began a one-year maritime navigation test in April 2015. Each propeller is operated for 1500 hours in total, for a total of 3,000 hours.

The engineering team converted the tail shaft and rudder on the Gunnerus to a full-rotation permanent magnet thruster, but retained the original generator set on the ship, so that the overall ship propulsion efficiency and performance before and after the conversion can be strictly compared.

Throughout the trial, the researchers found that the propeller's motor operating efficiency was 97% at rated speed and the operating efficiency was very high in each power segment. In addition, the bogie tension of the whole ship can be increased by 20%, the speed can be increased by 1 knot under the same power input state, the air noise and structural noise level are also reduced, and the underwater noise level is significantly improved.

Captain Gunnerus Arve Knudsen said: "The ship's trajectory control and propulsion feedback are improved, and the handling and heading stability are greatly improved. This propeller is really impressive."

Compared to conventional thrusters, permanent magnet thrusters have fewer moving parts. The entire thruster is integrated into a propulsion unit by a ring-shaped permanent magnet motor, a propeller and a shroud. The hub bearing is designed to withstand high loads and requires only a small oil circulation pump for lubrication. This system consumes much less lubricant than conventional propellers, so environmental damage can be greatly reduced in the event of oil spills. The system uses biodegradable bio-lubricants to meet the requirements of the US Environmental Protection Agency's General Ship License VGP-EAL.

The all-turn permanent magnet thruster is compact and easy to install and maintain. Only the slip ring box, steering motor and a very small lubrication bracket are required in the propeller chamber. Since the system uses an immersed motor, there is no need to install any cooling equipment, which saves a lot of installation space and reduces installation costs.

Gunnar Johnsen, head of marine electrical systems at Rolls-Royce, said: "The tests for Rolls-Royce full-turn permanent magnet thrusters show that it is fully efficient, reliable and durable. Low noise vibration, easy installation and maintenance, etc. We expect the overall maintenance cost of the system to be reduced by 50%. If the system does require maintenance, our equipment performance monitoring system can report the status of the relevant equipment in real time, so that customers can prepare maintenance plans in advance. ."

Recently, Rolls-Royce has introduced a series of deck machinery and propulsion systems using permanent magnet technology. This full-turn permanent magnet thruster is one of them. From 2007 to 2009, we conducted a large number of experiments on the Olympic Octopus for the world's first permanent magnet propeller, and then commercialized in 2012. So far, it has been running for 5,000 hours without any maintenance requirements.

The series of full-rotation permanent magnet thrusters will be officially launched in 2017. The first batch will be AZP-PM 120, rated at 1,800-3,500kW, and then will be launched AZP-PM-085/100/150 three respectively. It covers a 900-5,000 kW power segment and supports up to 24 knots.

The new AZP-PM series thrusters will be equipped with an L-drive configuration. The submersible unit is common to the traditional Azipull series propellers, but the upper unit is quite different and has a vertical permanent magnet motor. The permanent magnet motor is compact and fixed with a mounting flange. The small size eliminates the need for an upper gearbox. Compared to conventional Z or C drives, the L-drive scheme greatly simplifies complex configurations such as couplings, pedestals and motors.

Thanks to the new welded housing assembly process, the overall installation of the unit is greatly simplified. The main body is a cylindrical steel structure, and the connection part between the top and the mounting flange is conical. It is very simple and convenient to weld with the hull structure, and is especially suitable for the installation of the full-turn propeller.

The propellers of the AZP-PM full range of propellers are available in three different forms, including pitch propellers, fixed pitch propellers and cistern propellers. Users can choose between ship type and operating mode. These three types of propellers have been fully validated in existing Azipull full-turn propellers.

Gunnar Johnsen, head of the ship electrical system at Rolls-Royce, introduced the new AZP-PM series thrusters: "The permanent magnet motors have shown very high operating efficiency over the entire speed range and have been effectively reduced. The space requirements of the propeller chamber. The propulsion system fully meets the corresponding ice class requirements of the ship. In addition, the Azipull full-turn propeller has a very mature and excellent performance in terms of propulsion efficiency and fluid mechanics efficiency, and the combination with permanent magnet technology makes the whole The system is even better."

Since its launch in 2003, the Azipull series of propellers with pull-type propellers and streamlined underwater fins have gained wide acceptance in the market. So far, the full range of propellers has produced more than 450 sets, with mature performance in direct mechanical transmission and separate motor drive.