半浸式螺旋桨水动力性能的数值模拟研究

Numerical study of the hydrodynamic performances of surface piercing propeller

针对半浸式螺旋桨的水动力性能问题,应用CFD方法对其流场进行了数值模拟研究,并把结果与实验进行比较。通过求解雷诺平均方程(RANS)来模拟流场,采用SST k-ω湍流模型来计算RANS方程中的雷诺应力。利用Fluent中的明渠流动(Open Channel Flow)功能模拟空泡水筒中的气液两相流动,采用VOF方法捕捉自由液面。应用滑移网格法完成搅拌桨的转动,实现了对一个五叶右旋半浸式螺旋桨的数值模拟。研究结果表明,桨的尾流场形态与实验结果吻合地较好,证明了CFD方法预测半浸式螺旋桨性能的有效性。在较低浸入深度时,数值模拟可以很好地预测半浸式螺旋桨的性能。随着浸入深度的增加,推力系数和效率的预测结果基本准确,扭矩系数的预测结果有一定偏差。从数值计算结果中,可以获得宏观力的脉动曲线和完全入水桨叶的压力分布,并且可以对桨叶出水和入水过程进行详细的研究。

Aiming at investigating the hydrodynamic performances of surface piercing propeller, CFD method was applied to simulate its flow filed. The numerical results were compared with the experimental data. A right-hand surface piercing propeller with five blades was modeled. Its flow field was solved through Reynolds Averaged Navier-Stokes equation（RANS）. SST k-ω turbulence model was utilized to calculate Reynolds stresses in the RANS equations. The Open Channel Flow model in Fluent was employed to simulate the gas-liquid flow in cavitation tunnel. The free surface was captured through the VOF method and the rotation of the propeller was handled by means of sliding mesh. The results indicate that the wake field shape is in satisfactory agreements with the experimental data. It proved the validity of CFD method to predict the performance of surface piercing propeller. In less depth of immersion, numerical simulation can supply a good prediction of propeller performance. With the increase of the immersing depth, the results are accurate enough for thrust coefficient and efficiency. However there are some deviations for torque coefficient prediction. The numerical results can provide the fluctuating curve of macroscopic forces and the pressure distribution contour of a fully-submerged blade. The process of entry and exit of the water can also be researched in detail.