The vortex pump is a kind of vane pump, which is mainly composed of an impeller, the pump body and the pump cover. The impeller is a disk, and the blades on the circumference are uniformly and radially arranged. An annular flow channel is formed between the pump body and the impeller, and the suction inlet and discharge outlet are in the outer circumference of the impeller. There is a baffle between the suction inlet and the discharge outlet, so as to separate the suction inlet and the discharge outlet.
We divide the fluid in the pump into two parts: the fluid between the blades and the fluid in the flow channel. When the impeller rotates, the circumferential velocity of the liquid in the impeller is greater than the circumferential velocity of the liquid in the flow channel under the action of centrifugal force, so the "annular flow" is formed. Besides, the liquid from the suction inlet to the discharge outlet follows the impeller forward. The synthesis of these two kinds of movements makes the liquid produce the same "longitudinal vortex" as the impeller, thus getting the name of vortex pump. In particular, the circumferential velocity of the liquid particle in the channel of the pump body is less than the circumferential velocity of the impeller.
In the longitudinal vortex process, the liquid particles enter the impeller blades several times and transfer energy to the liquid particles in the flow channel through the impeller blades. Each time a liquid particle passes through the blade, it gains energy. This is also the reason why vortex pumps have a higher head than other vane pumps in the case of the same impeller diameter. However, not all of the liquid particles will pass through the impeller. The "annular flow" decreases as the flow rate increases. When the flow rate is zero, the "annular flow" is strongest and the head is highest.
Relying on the force of the rotating impeller on the liquid, the vortex pump endows the liquid with an impulse in the direction of liquid movement to transfer the kinetic energy, so as to achieve liquid transport. The impeller is a disc of uniform thickness, and there are many small radial blades on both sides of its outer edge. There is an annular flow channel of equal cross-section on the pump shell corresponding to the blade, and the whole flow channel is divided into the suction inlet and discharge outlet by a cut-water, which are connected with the suction and discharge pipeline of the pump respectively. The liquid in the pump produces a certain centrifugal force when rotating with the impeller. The liquid is thrown outwards into the annular flow channel of the pump shell and forced to flow back under the limitation of the flow channel shape, and then re-enters the other leaf channel behind the blade root. Therefore, the movement of the liquid between the blade and the annular flow channel is a forward spiral for the static pump shell; and for the rotating impeller, it is a backward spiral. The vortex pump is named because of the vortical motion of the liquid.