When the propeller of a large oil tanker is in operation, the propeller blades of the large oil tanker generate a force with the water, causing the water to produce a reaction force on the hull, which in turn drives the hull forward. In the long-term use of large oil tanker propellers, the fatigue limit is not required due to the different materials used for large oil tanker propellers.
The deformation and fracture of large oil tanker propellers occur over time, and in addition to this force, there are still many uncertain factors, such as the erosion of water causing the blade thickness to become thinner, and the thinning of large oil tanker propellers causing an increase in blade deformation.
Large bulk cargo propeller - propeller sound
Large bulk cargo propellers - In this case, the broken blades need to be repaired using patching methods, systematically repairing surface cracks, pitting, corrosion and other defects, correcting deformation, and further. Large bulk cargo propellers need to undergo quality inspections on static balance, propeller pitch, etc. They must also meet the requirements of relevant standards.
Large container propeller - blade deformation
The sound of a large container propeller is caused by the frequency of the vortices generated by the blades and the frequency of the large amplitude structural response of the blades. The energy generated by the large container propeller causes self-excited vibration of the blades. There are the following methods to weaken the sound:
1. Large engineering ship propeller - trimming the trailing edge of the blade. To change the distribution frequency, it is necessary to first change the thickness of the trailing edge of the blade. The structural shape of the trailing edge will affect the frequency and strength of the distribution vortex, and also determine the ratio of the transverse and longitudinal spacing of the vortex street formed. Large engineering ship propellers, however, do not have the sole purpose of eliminating noise. The weakening of the trailing edge of large engineering ship propellers can affect their strength, resulting in a decrease in strength that cannot meet work requirements.
2. 56M engineering ship propeller - increase the damping of the propeller blades. Using high damping materials to manufacture propellers can also eliminate rattling.
3. 56M engineering ship propeller - Near the back edge of the blade, at about 1/15 of the chord length of the profile, the 56M engineering ship propeller is fixed with small metal protrusions at equal intervals along the radial direction, and made into a semicircle.
4. Fixed pitch propeller - Replace the blade with a serrated structure along the edge, with a tooth height of about 7% of the chord length. The bottom edge of the fixed pitch propeller tooth is equal to the tooth height.
