The hull-propeller interaction for the underwater vehicle with the pump-jet propulsor is simulated and analyzed based on the Reynolds-Averaged Navier-Stokes (RANS) method. A new calculation method of thrust deduction factor for the pump-jet propulsor is proposed to balance the influence of the duct. The results demonstrate that the thrust deduction factor will not be affected by the installation position of the pump-jet propulsor, indicating that the new proposed method is more suitable for the calculation of the thrust deduction factor for the pump-jet propulsor.
With the development of modern shipbuilding industry, more and more new propulsors have been invented and put into practical engineering applications, such as pump-jet propulsor (PJP), water-jet propulsor, rim-driven thruster, podded propulsor and so on. Among them, the PJP has received much more attention for its superior propulsion performance and low noise performance. The PJP is composed of rotors, stators and a duct which covers the rotor and the stator. The rotor can produce the required thrust by interacting with the inflow as similar to the propeller blades. The stator is a set of blades with a certain angle to the inflow, which can fix the duct, and increases the propulsion efficiency by recovering rotor wake energy (Jiang, 2017). It can be divided into two categories: the pre-swirl stator and the post-swirl stator. The former one can generate pre-swirling inflow to the rotor, while the latter one can recover the wake energy. The duct with a hydrofoil profile, generally a decelerating duct, can reduce the flow velocity around the rotor and thereby alleviate the occurrence of cavitation, and can also reduce the noise, as well as protect the rotor and the stator from foreign objects. According to the position of the stator, the PJP can be divided into the PJP with the pre-swirl stator that is mostly used for submarines and the PJP with the post-swirl stator that is often used for torpedoes. The complex configuration of the PJP generally imposes limitations on the experimental study of the hydrodynamic performance of the PJP. However, the computational fluid dynamics (CFD) tools are often used to numerically simulate the flow field around the PJP, because it is more convenient to analyze the forces and moments generated by different parts of the PJP. Rao (2012) used the RANS method with the sliding mesh technology to study the unsteady hydrodynamic performance of the PJP with the pre-swirl stator, and analyzed the relationship between the unsteady alternating frequencies and the amount of the blades. Lu et al. (2016) calculated the open water performance of the PJP by using the RANS method with the SST k − ω turbulence model, showing good agreement with the open-water efficiency that was obtained from the experimental data. Mehran et al. (2017) investigated the hydrodynamic performance of the ducted propeller at different advance coefficients by using the RANS method with the periodic computational domain to reduce the computational time. The transient flow around the PJP was then numerically simulated by using the numerical method that was validated against the available experimental data.