离心泵在启动时为什么要充满水？
离心泵在启动前，首先要充满水，以排出泵壳内的空气。由离心泵的工作原理可知，叶轮旋转时，水受离心力作用而被甩向叶轮外缘，叶轮中心处形成真空，水被吸入，形成水泵的连续工作过程。如果启动时泵体内不是充满水，而是充满空气，由于空气密度远远小于水的密度，在叶轮以同样的速度旋转时，空气产生的离心力将远小于水的离心力。这样会集聚在叶轮中心，使叶轮中心不能形成足够的真空，妨碍水的吸入，影响水泵连续工作过程的形成。因此，离心泵在启动前，必须首先充满水，排净泵体内的空气，才能维持水泵的正常工作(图\文www.wxjpby.com/)。
中译英：
Centrifugal pump before starting, must first be filled with water, to remove the pump casing of air. By the principle of centrifugal pump impeller rotates, the water that, by centrifugal force and is thrown to the outer edge of the impeller, the impeller center of vacuum, the water is sucked into the pump, forming a continuous working process. If you start the pump body is filled with water, but is filled with air, the air density is much less than the density of the water, the impeller to rotate at the same speed, air to generate centrifugal force is far less than that of water by centrifugal force. It will gather in the center of the impeller, the impeller center of the vacuum can not form enough, the way of water suction pump, continuous working process of formation. Therefore, the centrifugal pump before starting, must first be filled with water, drain the air inside the pump body pump, to maintain the normal work.
