斜流工况下泵喷推进器推进性能数值分析

Numberical Simulation of Propulsion Performance of a Pump-Jet Propulsor in Oblique Flow

关键词:  泵喷推进器  推进性能  计算流体力学  斜流  数值模拟

Key words:  Pump-jet propulsor  Propulsion performance  Computational fluid dynamics  Oblique flow  Numerical simulation

摘要:

斜流入水的现象在推进器的运行过程中广泛存在，会对推进器的水动力性能造成不利影响。为了分析斜流工况对泵喷推进器推进效率及流场造成的影响，采用分块网格技术，对泵喷推进器内外流场进行了结构化网格划分。基于RANS方程，SST k-ω湍流模型，对不同转速（n=3000，3600，4200r/min）、不同斜流角（β=0°，5°，10°，15°，20°，25°，30°，40°）的泵喷推进器进行了数值模拟。数值模拟方法通过Ka4-70/19A导管桨进行了验证，计算值与实验值吻合情况良好。研究结果表明：小角度下，斜流角的改变对泵喷推进器的效率影响很小；斜流角>20°时，斜流角增大将使推进效率明显减少，这是由于泵喷推进器内流场分布不均，出现了水流聚集区和分散区，降低了泵喷推进器的平衡性以及对流体的加速效果；斜流角越大，叶尖间隙对主流影响越大，造成的能量损失越大。

Abstract:

The phenomenon of oblique inflow is widespread in the operation of the propeller， which will adversely affect the hydrodynamic performance of the propeller. In order to analyze the effects of oblique flow on the propulsion efficiency and flow field of the pump-jet propulsor，multi-block was adopted to create the grid of all computation domain in a pump-jet propulsor. The method based on RANS equation and the SST k-ω turbulence model were adopted to study the hydrodynamic performance of a pump-jet propulsor in different rotation speed （n=3000，3600，4200r/min） and different oblique inflow angles （β=0°，5°，10°，15°，20°，25°，30°，40°）.The numberical simulation method was verified by duct propeller Ka4-70 with duct 19A and the calculated values were in good agreement with the experimental values.The results show that the propulsion efficiency changes tinily in little oblique angle and decreases significantly in oblique angle larger than 20°.This is because the distribution of the flow in pump-jet propulsor is uneven，and the concentration area and dispersion area appear，which decrease the balance of pump-jet propulsor and acceleration performance of the pump jet.Furthermore，the influence of tip clearance on the main flow increaces in larger oblique angle，and it also leads to the greater energy loss.