Ring propeller
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The ring propeller is a new type of propeller known internationally as the Rim Thruster or Inline Thruster , which was presented as a novelty at Shipbuilding, Machinery & Marine Technology 2010 by the companies Voith and Van der Velden .
principle
The ring propeller is a propeller that, in contrast to previous propellers, does not have a hub . Conventional propellers are driven by a propeller shaft from turbines , diesel engines or electric motors. The pod is a more recent development , here the electric motor with the propeller is located in a closed housing under water. With the ring propeller, also known as inline thruster or inline propusor, the individual propeller blades are attached to an outer ring, this outer ring is designed as the rotor of an electric motor and provides the necessary torque. Similar to the pod, the ring propeller can be made fixed or rotatable.
Advantages and disadvantages
The great advantage of this principle is the compact design, which enables relatively easy integration in many applications. Furthermore, no shaft or gear is required, as the propeller is driven directly by the electromagnetic field of the electric machine. The sealing of moving parts can also be omitted because the rotor and stator can be completely sealed separately. Overall, this type of drive is characterized by a very low level of noise, because there is no gap between the wing tip and the tunnel and there is no gear.
A disadvantage is a comparatively lower degree of efficiency because of the friction losses in the rotor bearing and in the gap between the rotor and stator.
application
This special construction can be used like a conventional propeller for ship propulsion, as a cross-thrust control system or as a pod and is currently available with outputs of up to 1500 kW. Such a system was designed by Voith Turbo for a jack-up ship 131 meters long and 39 meters wide for the construction of wind turbines . The inner propeller diameter is 2.3 meters.