Session: 06-14-02 Underwater Vehicles and Design Technology II

Paper Number: 79760

79760 - Numerical Analysis on Model- and Full-Scale Unsteady Propeller Force for Underwater Vehicle 

Hydroacoustics has attracted much interest for controlling the stealth capability of naval vessels. Marine propellers experience unsteady forces because they rotate in circumferentially non-uniform wakes of ship hulls. The unsteady propeller forces transmit via the propeller shaft and produce undesirable noise at the frequencies of the multiples of the number of propeller blades and its rotational speed, called the blade rate (BR) noise. Submarines and other underwater vehicles deployed for undersea defense systems and oceanographic surveys require extensive specifications for the acoustic signature to perform covert missions. Therefore, unsteady propeller forces must be studied to reduce the resulting BR noise for improving the stealth performance of these vehicles. In this context, the unsteady propeller force of an underwater vehicle was analyzed along both the axial and transverse axes at the model scale and full scale, based on Reynolds-averaged Navier–Stokes simulations. The DARPA SUBOFF submarine with the INSEAN E1619 propeller was adopted as a benchmark model. The propeller rotational speeds under self-propelled conditions were determined using the body-force propeller method. The dominant harmonics of the unsteady propeller forces were analyzed using the Fourier series. The effects of pre-swirl flow generated by the helmed stern planes were also investigated. Reynolds scaling was examined to predict the amplitudes of the propeller forces at full scale, based on the model-scale values. The amplitudes for the axial propeller forces were significantly reduced by the pre-swirl flow generated by the helmed stern planes at both the model and full scales. The predicted amplitudes of the dominant harmonic in the full scale agreed well with the computational values over the range of the tested Reynolds numbers.

Presenting Author: Kenshiro Takahashi Naval Systems Research Center, Acquisition, Technology & Logistics Agency

Authors:

Kenshiro Takahashi Naval Systems Research Center, Acquisition, Technology & Logistics Agency
Jun Arai Naval Systems Research Center, Acquisition, Technology & Logistics Agency
Takayuki Mori Naval Systems Research Center, Acquisition, Technology & Logistics Agency