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Water-jet propulsion system with vectorised thrust
Published in Petar Georgiev, C. Guedes Soares, Sustainable Development and Innovations in Marine Technologies, 2019
A pump-jet, hydro-jet, or as it is called water jet is a device designed to produce a jet of water for marine propulsion. The traditional mechanical arrangement may be a ducted propeller (axial pump), centrifugal pump or mixed flow pump. The design also incorporates an intake to provide water to the pump and a nozzle to direct the flow of water out of the pump, see Figure 2.
Effects of the stator prewhirl angle on the unsteady force under uniform and turbulent inflow for a pump-jet propulsor: a numerical study
Published in Ships and Offshore Structures, 2022
Shuaikang Shi, Wanghao Tang, Xiuchang Huang, Hongxing Hua
In recent years, various novel propellers such as waterjet, ducted propeller, and pump-jet have been employed on ships and underwater vehicles. Among them, considerable attention has been paid to pump-jet owing to its superior hydrodynamic, cavitation, and noise performance (Henderson 1974). The pump-jet is composed of a stator, rotor, and duct. The stator is a stationary system fixed within the duct. The rotor is a rotating system that operates within a duct. The duct is an axisymmetric shroud that is coaxial with the rotor and stator (Bruce et al. 1974; Furuya and Chiang 1988). The pulsating force spectra of propeller are composed of a low-frequency discrete spectrum and a broadband random spectrum, which reflect the spatial inhomogeneity and temporal unsteadiness, respectively. The discrete spectrum at the Blade Passing Frequency (BPF) and its multiples are generated by non-uniform inflow caused by ship appendages, such as rudders and fairwater (Bennaya et al. 2014). The vortex generated by the interaction between the inflow turbulence and propeller leads to the broadband spectrum of unsteady force (Anderson et al. 2015). The energy of the broadband spectrum components spanned over a wide frequency band ranging from tens to hundreds of hertz, which would cause random vibrations in the propulsion shafting system. In a pre-swirl pump-jet, the rotor operates the non-uniform inflow induced by the pre-swirl stator, leading to a discrete spectrum at the Stator Blade Passing Frequency (SBPF) for a single blade of the rotor. In addition, under the combined influence of the temporal unsteadiness inflow induced by the inflow turbulence and the non-uniform inflow induced by the pre-swirl stator, the unsteady force of the rotor in the pre-swirl pump-jet becomes more complicated. Therefore, a deeper understanding of the rotor-stator interaction is of significance to the noise reduction design and propulsion performance design of the pump-jet.