A hydraulic pump (or fluid dynamics) is a type of device in which the movement of the liquid is supplied directly to the fluid itself. These devices do not need valves, even if they have the disadvantage that the efficiency and the flow rate decrease when there is an increase in the pressure in the outlet port. For correct operation, it usually needs to be partially filled with fluid, so it must be subjected to a priming operation so as to eliminate any air inside it. There are different types of hydraulic pumps that can be divided according to the operation: centrifugal pumps, magnetofluidodynamics, axial or hydraulic rams. Generally the pumps are used to move a liquid from a lower level to an upper level or to supply an adequate mechanical energy to a fluid.
Types of hydraulic pumps
A centrifugal pump uses the movement of an impeller to adequately move a fluid. So this device is able to transform the mechanical energy that is generated by a motor into kinetic energy and then into pressure energy that is supplied to the liquid. The fluid passes through the centrifugal pump radially or semi-axially. The impeller movement is able to determine a pressure difference inside the suction pipe allowing the water to rise up along the pipeline. Centrifugal pumps can be installed below or above the leaf. The first type is used when the hydraulic pump is positioned below the minimum level of the liquid to be aspirated. The second type that uses suction, but must not be too far above the free surface of the water to avoid cavitation.
Fluid dynamic pumps
A magnetofluidinamic pump is a device that exploits the force that a magnetic field is capable of imparting to a particle transiting orthogonally. In this kind of pumps the fluid is made to flow in a pipe that is immersed in a magnetic field with the field lines perpendicular to the axis of the duct. Inside the pipe instead an electric current is made to flow through the fluid, so that the effect is maximized. This type of machinery does not present cavitation phenomena, therefore it is less subject to wear phenomena. An axial pump is a device in which there is a propeller inside the tube that pushes the fluid with its rotary movement. In this type the fluid passes perpendicularly to the rotating system unlike the centrifugal one.
Water hammer pump
A water hammer with a water hammer uses a principle that is usually avoided. In fact the water hammer is the phenomenon that occurs when an incompressible flow is suddenly stopped, therefore the mechanical energy that the liquid possessed is transformed into a pressure wave that is dissipated in the form of heat. In a pump of this type the pressure caused by the fall of a liquid is exploited precisely to lift part of it to a higher level. This type of device does not require any type of power supply, but has the drawback that a large part of the liquid is lost. In fact, a ram pump is usually used in situations where there is a considerable amount of water that can be transported, so that the losses do not weigh on the water balance.