Do Propellers Sing?

Tuesday, February 01, 2011
The graphic shows the chamfering that goes from a 0.5 or 0.4 radius to the tip of suction side

By Leonardo Montoya, Rice Propulsion, in the January edition of MarineNews

Yes, sometimes they sing: Some propellers in service produce a high-pitched noise, often referred to as “singing.” This sound typically is a clear harmonic tone much like a humming or a ringing wine glass.

More of an annoyance than anything harmful, the causes of singing are not completely understood. Many theories have been put forward to account for the phenomenon of singing, but it appears to be affected by critical factors for which the theories make no allowance.

For instance, in some cases when a twin-screw vessel has one propeller that sings, the noise is eliminated just by switching the position of the propellers, or by replacing the propeller with an identical spare. Also, the fewer blades the propeller has, the less cases of singing are observed.

Mitigation of Singing: the Anti-Singing Edge
The singing is a function of propeller diameter and RPMs, boat speed and trailing-edge size (thickness) and roundness. In most of the cases, not much can be done on diameter, RPMs or speed, but we can modify the edge geometry. This has been the strategy for all efforts to eliminate singing.

Most propeller professionals (and others) are familiar with the anti-singing edge, a chamfering of the trailing edge, typically on the suction side. The intent of this shape is to avoid the creation of curving flow eddies by cleanly separating the flow off of the blade.

However the adoption of unduly thin edges can result in erosion or fracture of the blade near the edges. It is advised that an anti-sing edge be considered as a last resort to minimize the singing of an existing propeller.

Maritime Reporter June 2015 Digital Edition
FREE Maritime Reporter Subscription
Latest Maritime News    rss feeds

Marine Propulsion

Firefighting Vessel Delivered to the US Army

New Orleans based maritime solutions company Technology Associates, Inc. (TAI) informs it has completed its contract for the design and construction of a fast response

Yanmar Diesel Engines for Fast New Crew Tender

The expansion of the number of wind turbines out at sea near the northern Dutch coast was reason enough for Ubels Offshore to expand its fleet with a fifth ship last year.

Hapag-Lloyd's New Noses Lower Emissions

Hamburg based shipping company Hapag-Lloyd plans for 24 of the largest containerships in its fleet to get new bulbous bows by 2016, with some of the vessels also

 
 
Maritime Contracts Maritime Security Maritime Standards Navigation Port Authority Ship Electronics Ship Repair Ship Simulators Shipbuilding / Vessel Construction Sonar
rss | archive | history | articles | privacy | contributors | top maritime news | about us | copyright | maritime magazines
maritime security news | shipbuilding news | maritime industry | shipping news | maritime reporting | workboats news | ship design | maritime business

Time taken: 0.1557 sec (6 req/sec)