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Propulsion Mechanics of Rowing and Yulohing
Propulsive tools of man-powered ships have a considerable effect on the history of human development. The efficiency of these tools can even determine the fates of nations, dynastic changes, and even rewrite the history of human beings. Historically, these tools are predecessors of modern ship propulsion! However, the traditional CFD suffered some intrinsic problems in its fluid dynamics equations often resulting in serious inaccuracies. So, in this paper, we still rely heavily on experiment results of fluid dynamics as important references. First we demonstrate that some historical serious derivation errors in the momentum equations of fluid dynamics are due to a careless assumption of no-energy-loss condition. Secondly, we describe the motion of the traditional fixed stroke and the sliding stroke of rowing ships, and explain the reason why the latter would stand out. Then we discuss the energy distribution of rowing and the propulsive force for the hull from the view of drag and momentum conservation, with the aid of advanced rocket theorems. Then, we analyze the motions of yulohing, its advantages/drawbacks, and the reasons why it can provide high propulsive force. Also, in hope to enhance the propulsion efficiency of air/sea vehicles, we study the propulsion mechanics and control technique of rowing and yulohing, in reference to size of paddles, the evolutions of ship propulsion, the modern aircraft, and the propulsive method of various creatures including fish. In this paper, we also find that the yuloh, as a predecessor, eventually evolves to become the most advanced modern screw propeller due to its feature of drawing energy from flow. In fact, the modern screw propeller is just the rotating form of ancient yulohing, and reversely yulohing can be regarded as the reciprocating form of screw propeller! So, while making a comprehensive survey of the evolution of fish propulsion, and the man-powered ship propulsion, we cannot help but amazingly applaud for these ancient Chinese wisdom of yulohing.
|Appears in Collections:||機械工程學系所|
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