A method to get capture area of a waterjet propulsor inlet duct based on grid filter weighting

In order to get capture area and calculate performance of a waterjet propulsor inlet duct conveniently and fast, grid filter weighting method is proposed based on Computational Fluid Dynamic (CFD) technology in this paper. Numerical simulating of the inlet duct is carried out. Implementation process of this method is discussed in detail. With processing the data of solving results, parameters in capture area are got under different Inlet Velocity Ratio (IVR) condition with this method. Efficiency and hydraulic loss of the inlet duct are calculated for the waterjet propulsor. The results are compared with that got with semi-elliptical fitting method. The calculation results obtained with both methods show good consistency. When IVR equals to 0.6, the efficiency reaches a maximum value, about 0.943. And the hydraulic loss reaches a minimum value, about 0.76. In the whole IVR range, the relative error of efficiency between these two methods is less than 0.2%. The relative error of hydraulic loss of the inlet duct between these two methods is less than 1.3%. The calculating process and results show that this method is convenient to calculate efficiency and hydraulic loss of the waterjet propulsor inlet duct. It can be easily inserted into automatic optimization process of an inlet duct to improve thrust performance of vehicles equipped with waterjet propulsors.