螺旋桨吸气及其水动力性能

  目的  为探究螺旋桨吸气带来的危害，在船舶设计阶段考虑防止螺旋桨产生吸气现象，开展CFD数值模拟研究。  方法  计算不同浸深比和进速系数下某螺旋桨模型的水动力性能，分析螺旋桨吸气现象的特点及其推力和扭矩变化，以及对比桨叶非定常载荷的变化。  结果  结果显示：浸深比h/D=1.0时，螺旋桨未产生吸气现象，其推力和扭矩无明显变化；浸深比0.6≤h/D<1.0时，螺旋桨受自由液面的影响，其推力和扭矩有一定的降低；浸深比h/D<0.6时，尤其在低进速系数时，螺旋桨产生了明显的吸气现象，其推力和扭矩显著下降。  结论  研究表明，当浸深比较小、进速系数较低时，螺旋桨容易出现吸气现象，并伴随着推力和扭矩的突变及桨叶受力脉动增大。

Immersion of propeller

  Objectives  In order to explore the hazards of propeller ventilation and to prevent that during the ship design stage, a study of CFD numerical simulation is carried out.  Methods  The hydrodynamic performances of a propeller model with different immersion ratio and advance coefficients are calculated. The ventilation characteristics and the changes of propeller thrust and torque are analyzed. The changes of the non-constant loads of a blade are compared.  Results  The results show that, for the immersion ratio h/D=1.0, the propeller has no ventilation, and its thrust and torque also have no significant change. For 0.6≤h/D<1.0, the propeller is affected by the free surface, and the thrust and torque have a certain reduction. For h/D<0.6, especially at lower advance coefficients, the propeller has a significant ventilation phenomenon and see a large decrease in the thrust and torque.  Conclusions  The study shows that, it's possible the ventilation happens in small immersion ratios and at lower advance coefficients, accompanied with the thrust and torque descending rapidly and pulsing steeply.