Experimental Investigation of Propeller Wake Wash

螺旋桨尾流洗流实验研究

• 批准号: RGPIN-2016-03905
• 负责人: Veitch, Brian
• 金额: $ 2.11万
• 依托单位: Memorial University of Newfoundland
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=614708
• 关键词: Experimental; Investigation; Propeller; Wake; Wash

Navigation in ice-covered waters requires that vessels be capable of operating in natural ice conditions, such as broken pack ice and intact level ice. Conventional ice-breaking operations rely largely on the mass and power of the vessel to break through ice. The ship's structure must be correspondingly strong. Recent innovations in marine propulsion technology have provided opportunities to use propeller wake wash as another means to break, clear, and otherwise manage ice. Icebreaking operations employing propeller wake wash can reduce significantly the ship structure-ice interaction involved in conventional icebreaking, thereby reducing the likelihood of structural damage and accidental spills of fuel or cargo, and improving the operation’s energy efficiency. Propeller wake wash has been used for years by mariners to clear broken ice from shipping channels, but it has only been since the advent of azimuthing types of propulsors that it has been incorporated into operations by design. At present, the design is done on an ad hoc basis as there is limited fundamental understanding of how the wake wash develops downstream of the propeller and subsequently interacts with sea ice at the free surface. The proposed research will address this knowledge gap. The proposed research will characterize propeller wake wash in terms of the 3-D fluid velocity field downstream, including the velocity field at the free surface. The characterization will be based on laboratory experiments. Experiments will be done in the tow tank at Memorial University's Ocean Engineering Research Centre. Experiments will focus first on the propeller wake wash in the absence of ice, and then on the interactions of the wake wash and ice. The focus of interest in terms of ice features will be on pack ice. A semi-empirical mathematical model will be developed of the downstream wake, and the interaction between the flow at the free surface and its interaction with pack ice. The model of the wake wash field will include mean velocities, as well as of its variability throughout the downstream wake. It will be tested against field observations of ships in ice, as the final experimental element of the proposed work. The wake model will predict the downstream surface velocity field in terms of key factors: delivered power, depth of submergence of the propeller, and inclination angle of the propeller to the free surface. When coupled to the ice interaction model, the model should predict how wake wash can clear pack ice en masse downstream from the propeller. This will be useful for designers and operators, such as commercial shipping, the Coast Guard, Navy and others who navigate in ice in connection with transportation, exploration and defense. The proposed research covers a 5 year time span. Four Master’s students will work on this program. All graduate students will be in a thesis-based degree program.

在冰层覆盖的水域航行要求船只能够在自然冰条件下作业，如破碎的浮冰和完整的水平冰。传统的破冰作业在很大程度上依赖于破冰船的质量和功率。这艘船的结构必须相应地坚固。最近船舶推进技术的创新为使用螺旋桨尾流洗涤作为另一种破冰、清理和管理冰层的手段提供了机会。采用螺旋桨尾流冲刷的破冰作业可以显著减少常规破冰中涉及的船舶结构与冰的相互作用，从而降低结构损坏和燃料或货物意外泄漏的可能性，并提高作业的能源效率。螺旋桨尾流清洗多年来一直被水手用来清除航道上的碎冰，但直到方位类型的推进器出现后，它才被设计成投入运营。目前，由于对尾流如何在螺旋桨下游发展并随后与自由表面的海冰相互作用的基本了解有限，设计是在特别的基础上进行的。拟议的研究将解决这一知识差距。 这项研究将根据螺旋桨下游的三维速度场，包括自由表面的速度场来表征螺旋桨尾迹洗涤。表征将以实验室实验为基础。实验将在纪念大学海洋工程研究中心的拖曳水箱中进行。实验将首先集中在无冰情况下的螺旋桨尾迹洗，然后研究尾迹洗与冰的相互作用。就冰层特征而言，人们感兴趣的焦点将是浮冰。建立了一个关于下游尾迹的半经验数学模型，以及自由面流动与积冰相互作用的数学模型。尾迹洗涤场的模型将包括平均速度，以及其在整个下游尾迹中的可变性。它将与冰中船只的现场观测相对照进行测试，作为拟议工作的最后实验要素。尾迹模型将根据关键因素预测下游表面速度场：发射功率、螺旋桨沉没深度和螺旋桨相对于自由面的倾角。当耦合到冰相互作用模型时，该模型应该预测尾流洗涤如何清除螺旋桨下游的大量积冰。这将对设计者和操作员有用，如商业航运、海岸警卫队、海军和其他在冰中航行与运输、勘探和防御有关的人。 拟议的研究涵盖了5年的时间跨度。四名硕士研究生将参与这个项目。所有研究生都将参加以论文为基础的学位课程。