How does a centrifugal pump primarily achieve fluid movement?

A centrifugal pump primarily achieves fluid movement through a rotating impeller. In this type of pump, the impeller—often designed with curved blades—spins at high speeds, creating a centrifugal force that pushes the fluid outward from the center of the impeller. This action generates pressure that propels the fluid through the pump and into the discharge pipe. The efficiency of this movement is largely dependent on the design of the impeller and the speed of rotation, which can be adjusted to meet various flow demands.

In contrast, other methods mentioned, such as using a reciprocating piston, involve different types of pump mechanisms like positive displacement pumps, which work by trapping a fixed volume of fluid and forcing it through the discharge. Thermal expansion involves changes in temperature affecting fluid density but does not actively move fluid. Gravitational flow relies on gravity to move fluids, typically in systems designed to utilize elevation changes rather than mechanical force. Therefore, the impeller's rotation is the primary and most effective means by which a centrifugal pump accomplishes fluid movement.