Feasibility of an innovative methodology for testing rowing shell/canoe/kayak performance, with application to numerical performance prediction

提高英国选手在赛艇/划桨项目中的表现的一种方法是提高他们的设备的性能;特别是船体。大量的努力已经花在改进材料和结构的船体，使他们更轻，更硬。然而，相对较少的科学努力已经花在改善形状的船体，以减少阻力，特别是在比较帆船赛事，如美洲杯。这似乎特别奇怪，因为小的增益可以在结果中产生巨大的差异。在雅典奥运会的男子赛艇项目中，速度每提高0.5%，就有6个项目的队员从银升到金牌;而速度每提高1%，就有8个队员从银升到金牌，7个队员从铜牌升到金牌，甚至有3个队员从第四名升到金牌。Vespoli是少数几家在20世纪90年代早期根据系统研究计划建造船只的公司之一，提供了在2000年悉尼奥运会上获得金牌的GB 8。传统船舶的减阻优化通常相当好理解;基于计算机的阻力预测技术相对准确和可靠，同时实验测试方法也很成熟。然而，划船/划桨船体的挑战要大得多。船的推进力是不稳定的，所以在整个划桨行程中推力是变化的。这部分是由于桨/桨相对于水的运动，部分是由于运动员和船之间的动量交换。因此，船的速度在整个行程中变化。除此之外，运动员的前后运动会导致俯仰运动，其中船头上升和福尔斯下降。这些非定常效应导致划水过程中阻力的变化，这使得阻力的预测变得相当困难。此外，典型的人造划船设施中的水深相当浅。在浅水中，在预测船产生的波浪系统时有一些额外的复杂性。这一点很重要，因为阻力的一个组成部分与船只通过波浪产生的辐射能量有关。由于改进设计所寻求的增益很小，用于评估设计的技术必须高度准确;因此，对划船/划桨船体形状设计的最小阻力的科学研究必须考虑这些额外影响，以便产生可靠和现实的结果。目前的建议旨在确定制定一项科学程序的可行性，该程序可用于以现实的方式评估船只的性能，包括不同速度、俯仰和浅水的影响。该程序包括三个组成部分：在试验水池中测试模型船体的技术;允许分析数据并按比例缩放到全尺寸的技术，以及用数字预测阻力的技术。将设计、建造和调试一个实验装置，该装置将使试验水池中的比例模型船体形式的真实运动包括速度变化和俯仰运动。将对正在划船的船只进行全尺寸测量;所获得的数据将用于检查将试验水池数据按比例缩放到全尺寸的技术。最后，目前正在开发的非定常阻力预测的数值方法，将扩展到解决与划船/划桨huls.If方法是可行的，预计未来的研究将包括现有设计的评估，并优化船体形状，以生产更快的船，在现实条件下减少阻力相关的特殊问题。人们还预计，对这些复杂流动现象的基本认识将得到提高，从而在未来产生更好的非定常阻力预测技术

One way to improve the performance of UK competitors in rowing/paddling events is to improve the performance of their equipment; in particular the boat hulls. A lot of effort has been spent in improving the materials and construction of the hulls to make them lighter and stiffer. However comparatively little scientific effort has been spent on improving the shape of the hull to reduce the drag, especially in comparison with sailing events such as the Americas Cup. This seems particularly strange since small gains can make huge differences in results. In the mens' rowing events at the Athens Olympics, an increase in speed of 0.5% would have taken crews in six events from silver to gold medals; whilst an increase of 1% would take all eight crews from silver to gold, seven crews from bronze to gold, and even three crews from fourth place to gold. One of the few companies who have built boats based on a systematic research programme in the early 1990s, Vespoli, supplied the GB eight which won gold at the 2000 Sydney Olympics.Optimisation of conventional ships for reduced drag is generally quite well understood; computer-based drag prediction techniques are relatively accurate and reliable, whilst experiment testing methodology is also well established. However the challenges for rowed/paddles hulls are considerably greater. The propulsion of the boat is unsteady / so the thrust varies throughout the rowing/paddling stroke. This is partly due to the movement of the oars/paddles relative to the water, and partly due to the exchange of momentum between the athletes and the boat. As a consequence the speed of the boat varies throughout the stroke. In addition to this, the movement of the athletes backwards and forwards leads to a pitching motion, where the bow of the boat rises and falls. These unsteady effects lead to a variation in drag through the stroke, which makes prediction of drag considerably more difficult.Additionally, the depth of water in a typical man-made rowing facility is quite shallow. In shallow water there are some additional complications in predicting the wave system generated by the boat. This is important, since one component of the drag is related to the energy radiated from the boat through the waves generated.Since the gains which are sought by improved design are so small, the techniques used to assess designs must be highly accurate; therefore a scientific study of the design of rowing/paddling hull form for minimum drag must consider these extra effects in order to generate reliable and realistic results. The current proposal is aimed at establishing the feasibility of developing a scientific procedure which can be used to assess the performance of boats in a realistic manner, including the effects of varying speed, pitching and shallow water. The procedure consists of three components: a technique for testing model hulls in a test tank; a technique to allow the data to be analysed, and scaled to full scale, and a technique for predicting the drag numerically. An experiment rig will be designed, built and commissioned which will enable realistic motions of a scale model hull form in a test tank including both the speed variation and the pitching motion. Full-scale measurements will be made on boats being rowed; the data obtained will be used to examine the techniques for scaling the test-tank data to full scale. Finally a numerical method for unsteady drag prediction, currently under development, will be extended to address particular issues relevant to rowing/paddling hulls.If the method is feasible it is anticipated that future studies will include assessment of existing designs, and optimisation of hull-forms to produce faster boats by reducing drag under realistic conditions. It is also anticipated that fundamental understanding of these complex flow phenomena can be improved, leading to better prediction techniques for unsteady drag in the future