样本视频成绩单
以下是为此模块提供的视频示例的成绩单：
这是一个安全的赌注，你已经知道一个泵是什么以及它所的东西。但是，您可能不知道的是，许多泵类型移动流体，它们的结构和操作由它们正在移动的流体类型决定。泵的根定义只是一种使用机械动作移动流体的装置。有两种类型的泵：正排量和旋转动力学。正排量泵“抓住并转移”，作为由转子，齿轮，活塞或在泵入口处产生空隙的一些其他装置捕获的固定量的流体。然后将其机械地移动（移位）到泵放电。Displacement pumps provide a constant flow at a given speed regardless of the pressure in the system. An example of these basic pumps are the oil and water pumps in your car’s engine. While positive displacement pumps are easy to understand, rotodynamic pumps are a bit less intuitive. Rotodynamic pumps “throw and go” by transferring kinetic energy to the water via rotation. The fluid is thrown within the pump, and in turn, kinetic energy transfers to the fluid as its velocity increases. As the pump discharges, the velocity reduces, and the energy converts to potential energy in the form of increased pressure. Note that centrifugal pumps do not “suck” water in. They create conditions where the pressure of the system at the pump inlet (the suction head), pushes the water into the pump. Specifically, as the fluid leaves the pump, system pressure at the pump inlet pushes fluid into the void left behind the discharged fluid. There are numerous types of rotodynamic pumps, but the most common in commercial buildings are the centrifugal type.
