Pump Performance Laboratory
...ranging from aircraft engines to steam turbines. Turbomachinery refers to a group of machines which rotate, such as fans, turbines, and pumps. These machines are divided into two groups: (1) those that extract energy (turbines) and those that add energy to the fluid (pumps). Turbomachinery is a common application in engineering where fluid machinery design is of interest, where the pump in this discussion gets the attention. Hydraulic machines like pumps transmit power by means of a working fluid. Pumps all have a common practice to increase the pressure of a fluid by converting its kinetic energy to pressure energy. Pumps are divided into Positive-displacement (PDPs) and dynamic pumps.
Positive-displacement pumps force fluids by volume changes. A cavity opens, and the fluid is admitted through an inlet, trapped, and then squeezed through an outlet. Their great advantage is the delivery of any fluid regardless of its viscosity. On the other hand, dynamic pumps add momentum to the fluid by means of fast-moving blades or certain special designs. There is no closed volume, the fluid increases momentum while moving through open passages and its high velocity is converted to a pressure increase by exiting into a diffuser according to White [1].
The most common application is the centrifugal pump, which basically consist of an impeller rotating within a spiral casing. Fluid enters the pump axially through a suction pipe (via the eye of the impeller); discharged radially from the impeller around the entire circumference into the casing. The casing 'collects' the fluid, which has kinetic energy, decelerates it to increase the pressure of fluid. Then the fluid is discharged throughout the delivery flange.
Performance charts are used as a guideline to select a pump that would suit one's requirements. The optimal or rated and half rated speed for a 'family' of pumps...
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