Singing Propellers—Solutions and Case Histories
This paper examines the hydroacoustic processes involved with "singing propellers" aboard marine vessels. Methods are presented to determine the potential for a resonant response of a propeller to a vortex shedding excitation—a phenomenon known as "singing." Methods are provided to determine the likely shedding frequency and structural natural frequency for propeller blades. Diagnostics procedures to determine the presence of singing are explored. Measured and theoretical differences between the blade's natural frequency response in air and in-water are explored. Treatments are identified to change the vortex shedding frequency or to de-tune the structure. Case histories are detailed showing the potential magnitude of the problem and effective solutions.