Purpose

Hydrodynamic forces and efficiency of bare propeller and ducted propellers with a wide range of advance ratio (J) and attack angle (θ) are examined. The thrust and torque coefficients and the efficiency are presented and discussed in detail. The present results give a reliable guidance to the improvement of the hydrodynamic characteristics of ducted propellers.

Design/methodology/approach

The effect of a duct on the hydrodynamic performance of the KP458 propeller is numerically investigated in this study. Finite volume method (FVM)-based simulations are performed for a wide range of advance ratio J (0 ≤ J ≤ 0.75) and attack angle θ of the duct (15° ≤ θ ≤ 45°). A cubic computational domain is employed in this study, and the moving reference frame (MRF) approach is adopted to handle the rotation of the propeller. Turbulence is accounted for with the RNG k-ε model. The present numerical results are first compared against available experimental data and a good agreement is achieved.

Findings

The simulation results demonstrate that the hydrodynamic forces and efficiency increases and decreases with J, respectively, at the same attack angle. In addition, it is demonstrated that the hydrodynamic forces and efficiency are both improved due to the presence of the duct, which eventually leads a better hydrodynamic performance at high advance ratios. It is further revealed that as the attack angle increases, the pressure difference between the suction- and pressure-surfaces of the propeller is also augmented, which results in a larger thrust. The wake field is more uniform at θ = 30°, suggesting that a higher efficiency can be obtained.

Originality/value

The present study aims to investigate the effect of a duct on the KP458 propeller subjected to uniform inbound flow. The relationship between the uniform incoming flow and the attack angle of the duct is mainly focused, and the design of the ducted propellers for any ship hull can be improved according to this relationship.

中文翻译：

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导管对船用螺旋桨水动力性能的影响

目的

研究了具有宽范围的提前比 ( J ) 和攻角 ( θ )的裸螺旋桨和导管螺旋桨的水动力和效率。详细介绍和讨论了推力和扭矩系数以及效率。目前的研究结果为改进涵道螺旋桨的水动力特性提供了可靠的指导。

设计/方法/方法

本研究对管道对 KP458 螺旋桨水动力性能的影响进行了数值研究。对宽范围的提前比J (0 ≤  J  ≤ 0.75) 和管道的攻角θ (15° ≤  θ  ≤ 45°)执行基于有限体积法 (FVM) 的模拟。本研究采用三次计算域，并采用移动参考系（MRF）方法来处理螺旋桨的旋转。RNG k - ε模型考虑了湍流。目前的数值结果首先与可用的实验数据进行比较，并取得了良好的一致性。

发现

模拟结果表明，在相同攻角下，水动力和效率分别随J增加和减少。此外，研究表明，由于管道的存在，水动力和效率都得到了提高，最终在高推进比下获得了更好的水动力性能。进一步揭示，随着攻角的增加，螺旋桨的吸力面和压力面之间的压力差也会增加，从而导致更大的推力。尾流场在θ = 30°时更加均匀 ，表明可以获得更高的效率。

原创性/价值

本研究旨在研究管道对 KP458 螺旋桨在均匀流入流下的影响。主要关注的是均匀来流与导管攻角的关系，任何船体导管桨的设计都可以根据这个关系进行改进。