【Daily Question No. 268】November 15, 2020

Error. The main flow-through components of a centrifugal pump are the suction chamber, impeller, and discharge chamber. The water intake chamber is located in front of the inlet of the impeller, and it serves to direct the liquid toward the impeller ； Pressurization chambers mainly come in three forms: spiral pressurization chambers (volute type), guide vanes, and spatial guide vanes ； The impeller is the most important working element of a pump; it is the heart of the flow-through component, and consists of shrouds and blades in between. During operation, before a centrifugal pump starts working, the pump is first filled with liquid. Then the pump is started, and the impeller begins to rotate rapidly; the blades of the impeller propel the liquid to move. As the liquid rotates, it flows toward the outer edge of the impeller due to inertia. At the same time, the impeller draws in liquid from the suction chamber, and during this process, the liquid within the impeller flows around the blades. In the flow around the blade, the liquid exerts a lift force on the blade; in turn, the blade exerts a force on the liquid that is equal in magnitude but opposite in direction to this lift force. This force does work on the liquid, providing it with energy so that it flows out of the impeller, during which both the kinetic energy and pressure energy of the liquid increase. A centrifugal pump transfers the mechanical energy of the prime mover to the liquid by means of the action of the rotating impeller on the liquid. Due to the action of the centrifugal pump, as the liquid flows from the inlet to the outlet of the impeller, both its kinetic energy and pressure energy increase. The liquid discharged by the impeller passes through the discharge chamber, where most of its kinetic energy is converted into pressure energy, and then it is sent along the discharge pipeline. A vacuum or low pressure is created at the inlet of the impeller due to the discharge of liquid; under the action of the surface pressure (atmospheric pressure) in the liquid reservoir, the liquid is forced into the impeller’s inlet. Thus, the rotating impeller continuously draws in and discharges liquid.