Energy can exist in several forms. Hydraulic power is one that may possess a fluid. It can be in the form of kinetics, pressure, potential, effort or thermal energy. Fluid machinery is used to convert hydraulic energy into mechanical energy or mechanical energy into hydraulic energy. This distinction is based on the direction of energy transfer and forms the basis of fluid machinery grouping in two different categories. One of them is the production of energy machines that convert hydraulic energy into mechanical energy like turbines and motors, the other is to be able to consume machines doing the opposite like pumps, fans and compressors. Another classification for fluid machinery can also be made based on the movement of the moving parts. These are rotodynamic machines and positive displacement machines. Below is a detailed chart explaining classifications. Turbines, a subgroup of rotodynamic machines, are used to produce energy by converting hydraulic energy into mechanical energy. They are of different types according to your specification. The turbines can be subdivided into two groups, impulse and reaction turbines. In addition, because of the working fluid used, the turbines can be called steam turbines, gas turbines, wind turbines and water turbines. Water turbines convert the energy of water into mechanical energy. The Pelton turbine (or Pelton wheel), a thrust turbine, is one of the well-known water turbines.
In impulse turbines, the total available head is first converted to kinetic energy. This is usually achieved in one or more nozzles. The jets coming out of the nozzles hit blades attached to the periphery of a rotating wheel. Because of the rate of change of angular momentum and the movement of the vanes, the fluid performs the work in the impeller and therefore the energy is transferred. Since the energy of the fluid that is reduced when passing through the channel is completely kinetic, it follows that the absolute velocity at the output is less than the absolute velocity at the input (velocity of the jet). In addition, the pressure of the fluid is atmospheric and the relative velocity is constant except for a slight reduction due to friction.