Objectives  The effects of the key parameters of the inlet duct of a waterjet propulsor on its hydrodynamic performance are studied, providing references for the design of waterjet propulsors.

  Methods  Based on STAR-CCM+ software, the influence of the axis height and inlet angle of a waterjet inlet duct on its hydrodynamic performance under different intake velocity ratio (IVR) conditions is studied using steady Reynolds-averaged Navier-Stokes equations (RANS) numerical simulation. Numerical uncertainty analysis is carried out according to the international towing tank conference (ITTC) uncertainty analysis procedure. In this paper, the computational domain is discretized with hexahedral structured grids. The set of governing equations is closed using the Realizable k-ε two-layer turbulence model, and the discretization schemes are second-order accurate. The semi-implicit method for pressure linked equations (SIMPLE) algorithm is applied in the pressure-velocity coupling calculation.

  Results  The results show that the numerical uncertainty is less than 4%, indicating that the grids used in this paper yield well-converged and reliable numerical results.

  Conclusions  The efficiency of the inlet duct is higher in the range of IVR = 0.7~1.1. For large IVR, the inlet angle should be reduced. For small IVR, the axis height can be appropriately increased to improve the homogeneity of flow at the exit of the inlet duct.