关键词: 船舶, 混流泵, 喷水推进, 数值模拟, 叶片数

Abstract: The solution domain of waterjet propeller is analyzed and defined, and meshed by both structured and unstructured grids. The computational fluid dynamics (CFD) code solves 3D Reynolds-averaged Navier-Stokes equations in rotating and stationary coordinate systems with multiple reference frame method, and turbulence effects are modeled by using a shear stress transport (SST) turbulence model. Power absorption and thrust of six operating conditions of load and drive characteristics are used to compare the results of CFD with manufacturer data with the same pump revolution and ship velocity, which shows good agreement, indicating that the geometrical model is exact and CFD can be used to accurately predict water-jet propeller performance. Effects of changing the number of pump blades of both rotor and stator on the characteristics of flow pattern and water-jet propeller performance are principally investigated, which include the changes of rotor blade number from 5 to 7 to the effect of Stodola slip factor, of stator blade number from 9 to 13 to the effect of commutating result acting on the outflow of impeller, and of both rotor and stator blade numbers simultaneously to the new pump performance. Results of this study show that: given the condition of fixed pump revolution and vessel speed, the Stodola slip factor, the head, axial thrust and power consumption all go up as the number of rotor blades increases, but the efficiencies decline; the circumferential velocity of the nozzle outflow weakens with the increase of number of stator blades, but the improvement is approximately unchangeable when it comes to 11. The water-jet propeller performances are close when the stator blades are 10 and 11, both of their head and axial-thrust are bigger than that with 12 or 13 stator blades; the water-jet optimum performances can obtained when 5 blades of rotor match 9 blades of stator, while the rotor blades are 6 or 7, the best number of stator blades both are 11.

Key words: Blade numbers, Mixed flow pump, Numerical simulation, Ship, Water-jet propelling