How Does the Number of Slurry Pump Impeller Vanes Affect the Head?

The impact of the number of vanes in a slurry pump on the theoretical head.

The basic equations for slurry pumps are derived based on the assumption of an infinite number of vanes. Because slurry pump impellers have many vanes and long flow passages, they can better define the trajectory of the liquid within the passage, so the assumptions are relatively close to the actual flow. However, as the pump speed increases, the impeller diameter decreases, the number of vanes decreases, and the flow passage becomes wider, the assumed flow differs significantly from the actual flow. In an impeller with an infinite number of vanes, the distance between the vanes is extremely small, and the liquid flow is constrained by the vanes, leaving no room for free movement. It can only flow out of the rotating impeller along the gaps between the vanes, and the relative streamlines of the liquid completely align with the shape of the vanes. In an impeller with a finite number of vanes, the degree of liquid clamping by the vanes is greatly reduced, allowing the liquid's inertia to be fully realized. The actual flow in the impeller can be roughly considered to be the superposition of axial vortex flow and uniform flow (throughflow) through the stationary impeller. The superposition of these two flows causes slip in the relative velocity at the impeller outlet.