七叶侧斜螺旋桨设计参数对空泡性能的影响研究

Numerical Study on Effects of Design Parameters of Seven-Bladed Propeller with Skew on Its Cavitation Performance

关键词:  螺旋桨  空化  B样条，非定常流  参数优化

Key words:  Propeller  Cavitation  B spline  Unsteady flow  Parameter optimization

摘要:

为建立有效的预报螺旋桨空泡性能的方法，并基于该方法参数化分析七叶侧斜螺旋桨设计参数对空泡性能的影响，基于CFD方法建立了螺旋桨全湿流和空泡流非定常数值计算模型。通过对DTMB4381标准螺旋桨全湿流及空泡数值模拟结果与试验值的对比，验证了计算模型的准确性。通过对网格的收敛性分析，验证了收敛性并保证了计算精度。采用B样条曲线拟合方法拟合某七叶侧斜螺旋桨设计参数，通过改变控制点的值改变设计参数的分布型式。在此基础上重点分析了该七叶侧斜螺旋桨桨叶侧斜、弦长以及纵倾分布型式对螺旋桨空泡性能的影响，计算表明加大侧斜能够减小空泡面积，使空泡的随边边界向桨叶中心偏移,增大侧斜后螺旋桨平均推力较原型桨增大9.0%；增加盘面比会使空泡面积增大，但会降低螺旋桨单位面积的平均负载，增加盘面比后螺旋桨平均推力较原型桨增大11.8%；同时桨叶向压力面弯曲或向吸力面弯曲的计算都表明，一定程度的纵倾有利于改善螺旋桨的空泡性能。

Abstract:

In order to establish an effective method to predict cavitation characteristics of the seven-bladed propeller, the CFD method is adopted to predict unsteady cavitation on marine propeller in full wetted flow and cavitation flow. Then the effects of parameters of the propeller on its cavitation performance is analyzeed. The validation studies of the DTMB4381 propeller for unsteady cavitation flow are presented, and the calculation results are in acceptable agreement with the experimental results and observations. Through mesh convergence analysis, the convergency of the mesh is completed thus guarante the accuracy of calculation. Parameterization of the marine propeller is performed with the B splines for skew, chord and rake distributions. The effects of some parameters such as skew, chord and rake distributions on the seven-bladed propeller with skew cavitation performance are studied. The results show that with the skews increasing, the cavity enxtent will decrease and the cavitation boundary in side will shift to the centerline of the blade and the average thrust increased by 9.0% relative to the prototype. The cavity extent will increase and the average load per unit area of the propeller will decrease with the areo ratio increasing and the average thrust increased by 11.8% compared to the original propeller. The calculation of the rake distribution curvature to pressure side and suction side indicates that a certain degree of rake is benefical to improve the cavitation performance of marine propeller.