2. A water pump is a machine for conveying or pressurizing liquid. It transfers the mechanical energy or other external energy of the prime mover to the liquid, which increases the energy of the liquid. It is mainly used for conveying liquids, including water, oil, acid-base liquid, emulsion, suspension emulsion and liquid metal, as well as liquids, gas mixtures and liquids containing suspended solids. The technical parameters of pump performance include flow, suction, lift, shaft power, hydraulic power and efficiency. According to different working principles, it can be divided into positive displacement pump and vane pump. The displacement pump uses the change of its working chamber volume to transfer energy; Vane pumps use the interaction between rotating blades and water to transfer energy, including centrifugal pumps, axial pumps and mixed-flow pumps.