Vane

In centrifugal pump impellers, vanes are the radial or backward-curved blades mounted between the impeller's hub and shroud. Their primary function is to impart kinetic energy to the fluid entering at the impeller eye, accelerating it radially outward through centrifugal force. The vane's geometry—including inlet angle, outlet angle, curvature (profile), number of vanes, and thickness—directly influences pump performance parameters such as head, flow rate, efficiency, and Net Positive Suction Head Required (NPSHr). Vanes are critical for minimizing hydraulic losses, managing recirculation, and ensuring stable operation across the pump's performance curve.

Vanes operate on the principle of centrifugal force and momentum transfer. As the impeller rotates, fluid enters axially at the impeller eye and is captured between adjacent vanes. The curved vane surfaces guide the fluid radially outward, increasing its velocity and pressure. The vane's shape converts the motor's rotational energy into fluid kinetic energy (velocity) and, subsequently, into pressure energy as the fluid decelerates in the volute or diffuser. Key principles include the Euler pump equation, which relates vane geometry to energy transfer, and the prevention of flow separation through optimized vane angles and smooth profiles.