1. Suction chamber
The main flow parts of the vane pump are suction chamber, impeller and pressure chamber (including guide vanes).
The pump suction chamber is located in front of the impeller, and its function is to guide the liquid to the impeller. There are three forms: straight cone, elbow and spiral.
The pressurized water chamber is located on the periphery of the impeller, and its function is to collect the liquid flowing out of the impeller and send it to the discharge pipe. The pressurized water chamber mainly has three forms of spiral pressurized water chamber (volute), guide vane and space guide vane.
2. Impeller
The impeller is the core component that transfers the mechanical energy input by the prime mover to the liquid and improves the liquid energy. There are three types of impellers: open impeller, semi-open impeller and closed impeller. The open impeller has no front and rear discs but only blades, and is mostly used to transport liquids containing impurities. For example, the impeller of a sewage pump uses an open impeller. The semi-open impeller only has a rear disc. The closed impeller has both a front disc and a back disc. The impeller of the clean water pump is a closed impeller. The impellers of centrifugal pumps all adopt backward blade type.
The impeller should have sufficient strength and rigidity: the shape of the flow channel is streamlined in accordance with the law of liquid flow, the liquid flow velocity is evenly distributed, the flow channel resistance is as small as possible, and the flow channel surface roughness is small: the material should have good wear resistance Performance: The impeller should have good static and dynamic balance: simple structure and good manufacturing technology. The impeller of a centrifugal pump is generally cast.
3. Pump housing
The casing collects the liquid from the impeller, and converts part of the kinetic energy of the fluid into pressure energy, and finally guides the fluid evenly to the secondary impeller or to the discharge outlet. The shell structure mainly has two types: spiral and ring. The spiral pressurized water chamber not only functions to collect liquid, but also converts part of the kinetic energy of the liquid into pressure energy in the spiral diffuser. The spiral pressurized water chamber has the characteristics of convenient manufacture and high efficiency. It is suitable for single-stage single-suction, single-stage double-suction centrifugal pumps and multi-stage split centrifugal pumps. The casings of single-stage centrifugal pumps are mostly spiral volute casings. The annular pressurized water chamber is used in the water outlet section of the segmented multi-stage pump as shown in the figure. The cross-sectional area of the flow channel of the annular pressurized water chamber is equal, so the flow velocity is not equal everywhere. Therefore, there is always impact loss no matter in design conditions or non-design conditions, so the efficiency is lower than the spiral pressurized water chamber. Fixed guide vanes are also provided in some casings, which are the so-called guide vane casings.
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