在许多教科书和技术文章中讨论了带有球形弓的船的设计。它通常被称为理论或艺术,这是一种简短的方式,说没有人百分百肯定他们正在写什么。任何船舶在标准作业中面对的最强阻力来自船体在水中移动时的位移。爬上船头的海浪被推到一边的水比它可以移开的速度快。它需要很大的功率来克服水的粘度和质量,这意味着燃烧燃料,这增加了成本。球形弓是水线下方船体的延伸。它有许多微妙的形状变化,但它基本上是一个圆形的前部,当它融入传统的排水型船体结构时略微张开。这些向前突起大约是基座宽度的两倍,并且它们通常不会向前延伸超​​过弓的顶部。基本原则是创建一个低压区来消除弓形波并减少阻力。 1910年首次出现在特拉华号航空母舰上,球形船首是美国海军造船工程师David W. Taylor的一个有争议的设计。十年后,当客船开始利用设计来提高速度时,大部分争议都消失了。理想情况下,低压水锥将在道具之前坍塌。这使得桨叶能够抵抗并限制道具和方向舵的空化。船体弓形部分建造的船体今天很常见。在某些条件下,这种类型的设计在重定向流体动力阻力和阻力方面非常有效。有一种针对球形弓的运动,当“慢速蒸汽”是一种节省燃料的方式时,船舶可以提供更大的灵活性。有一些细节需要解决,但现代建筑商有专门的方法来分析和整合他们船体的所有水动力方面,这些方法是严格的秘密。球状弓在某些条件下效果最佳,良好的设计可在这些因素的整个范围内提高效率。速度 – 在低速时,球形弓将水捕获在灯泡上方而不形成低压区以消除弓形波。这导致阻力增加和效率损失。每种设计都具有所谓的最有效的船体速度,或通常只是船体速度。该术语是指船体的形状作用于水的速度,是产生最小可能阻力的一种方式。这种理想的船体速度可能不是船舶的最高速度,因为在某些时候,由船首特征产生的较低压力区域变得比必要的大。较低压力水的区域大于船体是低效的并且导致减小的方向舵响应。气蚀将导致道具效率降低,转向缓慢以及船体和驱动部件过度磨损。尺寸 – 49英尺(15米)以下的船只没有足够的湿润区域来利用球形弓。船体上的阻力与其湿润区域有关。灯泡的结构也增加了阻力,在某一点上,好处缩小到零。相反,具有高水位线到正面区域的较大型船舶最有效地使用球形弓。

美国波士顿大学制造学Assignment代写:球茎弓

The design of a ship with a bulbous bow is discussed in many textbooks and technical articles. It is often referred to as a theory or an art, which is a short way of saying nobody is 100 percent sure of what they are writing. The strongest resistance any vessel faces in standard operations comes from displacement as the hull moves through the water. Waves that climb the bow are water being pushed aside faster than it can move away. It takes a lot of power to overcome the viscosity and mass of water and that means burning fuel, which adds to costs. A bulbous bow is an extension of the hull just below the waterline. It has many subtle shape variations but it’s basically a rounded front portion that flares out slightly as it blends into the traditional displacement hull construction. These forward protrusions are about twice as long as the width of the base and they would usually not extend forward past the top of the bow. The basic principle is to create a low-pressure zone to eliminate the bow wave and reduce drag. First appearing on the USS Delaware in 1910, the bulbous bow was a controversial design of U.S. Navy Ship Architect David W. Taylor. Much of the controversy disappeared ten years later when passenger ships began exploiting the design to increase speeds. Ideally, the cone of lower pressure water will collapse just before the props. This gives the prop blades something to push against and limits cavitation at the props and rudder. Hulls built with bulbous bow sections are common today. Under certain conditions, this type of design is very efficient at redirecting forces of hydrodynamic resistance and drag. There is a movement against bulbous bows that allows greater flexibility of ships at a time when “slow steaming” is a way to save fuel. There are details to be worked out but modern builders have proprietary ways of analyzing and integrating all hydrodynamic aspects of their hulls and these methods are strict secrets. A bulbous bow works best under certain conditions and good design gives efficiency gains throughout the range of these factors. Speed – At low speeds, a bulbous bow will trap water above the bulb without forming a low-pressure zone to cancel the bow wave. This leads to increased drag and loss of efficiency. Each design has what is known as most efficient hull speed, or often just hull speed. This term refers to the speed where the shape of the hull is acting on the water is such a way to produce the minimum possible drag. This ideal hull speed might not be the top speed of a ship because at some point the lower pressure zone created by the bow features becomes larger than necessary. A zone of lower pressure water that is larger than the hull is inefficient and leads to reduced rudder response. Cavitation will lead to reduced efficiency of props, sluggish steering, and excessive wear of hull and drive components. Size – Vessels under 49 feet (15 m) do not have enough wetted area to take advantage of a bulbous bow. The amount of drag on a hull is related to its wetted area. The structure of the bulb also increases drag and at a certain point, the benefits shrink to zero. Conversely, larger ships with a high proportion of waterline to frontal area use the bulbous bow most effectively.

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