Axial-flow pump equipped with inducer are widely used in marine propulsion systems. The interaction of inducer and impeller has significant effect on the performance of pump. In this study, a special axial-flow pump is designed and analysed by CAD-CFD approaches to study the interaction of inducer and impeller. The pump includes two main elements, an inducer with 3 blades mounted on a conical hub and a 6-blade impeller. The blade angle of impeller is adjustable to generate different relative circumferential angles between the inducer blade trailing edge and the impeller blade leading edge. The 3D pump solid model is generated by taking the data file as interface between hydraulic-design and 3D modelling. A computational fluid dynamics code is used to investigate the flow characteristics and performance of the axial-flow pump. Numerical simulation is performed by adopting 3D RANS equations with RNG k-epsilon turbulence model. An unstructured grid system and the finite-volume method are used for the solution procedure of the discretized governing equations for this problem. The rotator-stator interaction is treated with a multiple reference frame (MRF) strategy. Computations are performed in different cases: 7 different relative circumferential angles (Δθ) between the inducer blade trailing edge and the impeller blade leading edge, 3 different axial gaps (G) between the inducer and the impeller. Variation of the hydraulic loss in the rotator is obtained with the change of delta theta. The numerical results show that the pressure generated is minimum in case of (G = 3%D). This indicates that the interference between inducer and impeller is strong if the axial gap is small. The pump performances are predicted and compared to the experimental measurements. The current investigation leads to a thorough enough understanding of the flow characteristics in axial-flow pumps with complex configurations. Recommendations for future modifications and improvements to the pump design are also given.

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