Wake Field

For a good propeller design it is necessary to have detailed knowledge of the nominal wake field and also the velocity distribution in the propeller plane. For experimental determination of wake fields, 5-hole ball probes, LDA or PIV (“Particle Image Velocimetry”), are used. It is standard that a 5-hole ball probe is used, offering the following options:

• Measurements in the propeller plane
• Measurements at the point of appendages, ie. the shaft struts
• With the probe, any coordinates can be approached
• 3-Dimensional wake field measurement

The standard measurement of a wake field for single screw vessels is carried out on 6 radii respectively, every 5 °. For measurements behind podded drives and shaft struts among others, the resolution is adjusted accordingly.

In addition to the experimental determination of the wake field, a calculation based on CFD simulation is possible. An advantage of a CFD simulation is the calculation of the velocity field for the Reynolds number of the full-size version.