Propeller Handedness

Propeller Handedness in the Marine Industry

The definition of the handedness requires a reference direction. Traditionally, the marine community defines the propeller handedness with respect to the stern of the vessel:

• A right-handed propeller rotates clockwise to produce forward thrust when viewed from the stern of the vessel.
• A left-handed propeller rotates counter-clockwise to produce forward thrust when viewed from the stern of the vessel.

The handedness of a propeller affects its shape. When you view a propeller from astern, the leading edges are farther away from you than the trailing edges. For example, the leading edges of a right-handed propeller are on the right and the propeller rotates clockwise when viewed from astern.

Propeller Handedness in STAR-CCM+

The selection of propeller handedness is available as an option as part of the Body Force Propeller method.

Generally, the design of a propeller is optimized to be used for forward motion. However in practice, a propeller can also be used for the reverse motion of a ship. Considering this fact, STAR-CCM+ does not use the stern of the vessel as the reference direction for the definition of left-/right-handedness as is the case for the traditional definition (see Propeller Handedness in the Marine Industry).

In STAR-CCM+, the local coordinate system of the virtual disk is used as the reference for defining the propeller handedness:

• A right-handed propeller rotates counter-clockwise when viewed from the positive direction of the z-axis of the local coordinate system of the virtual disk.
• A left-handed propeller rotates clockwise when viewed from the positive direction of the z-axis of the local coordinate system of the virtual disk.

The use of the local coordinate system of the virtual disk does not change the definition of handedness, only the reference axis for the direction of rotation is changed. This approach is consistent because the local coordinate system of the virtual disk changes according to the direction of propulsion of the vessel. The propulsion direction is specified in terms of the orientation specification of the virtual disk.

Rotation Direction

The Propeller Handedness Option is useful to prescribe or change the direction of rotation of the propeller - clockwise or counter-clockwise - in combination with the Operation Point Input Option and the Orientation Specification of the virtual disk.

To specify the operation point, there are three options available:

• Rotation rate with $\omega \ge 0$ .
• Thrust with $T\ge 0$ .
• Torque with $Q\ge 0$ .

The direction of propulsion is specified in terms of the orientation specification of the virtual disk. Forward and reverse propulsion direction is defined in terms of the selected coordinate system and its orientation with respect to the nose and the stern of the vessel.

In the following table, it is assumed that the Disk Normal and Coordinate System option is used as Orientation Specification. The combination of propeller handedness and orientation of the local coordinate system of the virtual disk and its effect on the directions of propulsion and propeller rotation is summarized as follows:

In the following figures, the orientation of the virtual disk is specified in terms of the Body coordinate system.The orientation of the local coordinate system of the virtual disk automatically adapts to the normal direction specified with respect to the Body coordinate system. The direction of propeller rotation for each type of handedness is shown:

Right-handed propeller in forward configuration	Right-handed propeller in backward configuration

Left-handed propeller in forward configuration	Left-handed propeller in backward configuration