Propeller design with pre-swirl stators

Abstract

Object and purpose of research. This research was intended to check if a pre-swirl stator installed before an open propeller of moderate skew could be a viable solution for non-cavitation hydrodynamic noise mitigation. This solution was compared with a typical open skewed silent propeller. Materials and methods. Design and verification calculations have been performed in a given wake field of pre-swirl stator. Pre-swirl stator was designed considering the wake field turn at the skew angles of typical propeller. Wake field behind the pre-swirl stator and design calculation of open propeller considering the heterogeneity of inflow were determined using the calculation methods. The tests and calculations of vibroacoustic parameters have been performed for evaluation of propulsion, cavitation and acoustic parameters of propellers with pre-swirl stators in comparison with open propeller. Main results. This work was also intended to answer the question if a moderate-skew propeller with pre-swirl stator could be an alternative to a silent skewed open propeller. To this effect, a model of propulsion system (propeller + pre-swirl stator) was designed and manufactured. This model was further used for comparative cavitation, hydrodynamic and acoustic testing in the cavitation tunnel, as well as for self-propulsion tests in deep-water towing tank. Conclusion. The tests have shown that propellers with pre-swirl stators have lower noise emission at high frequencies than open propellers. Cavitation and propulsion performance remain the same for both options.

Keywords

• propeller
• skew
• pre-swirl stator
• hydrodynamic noise
• hydrodynamic and cavitation performance
• acoustic measurements
• model test