How does coolant cavitation affect the efficiency and lifespan of a water pump impeller?

Coolant cavitation significantly reduces the efficiency and lifespan of a water pump impeller due to erosion and material fatigue. Cavitation occurs when the pressure of the coolant drops below its vapor pressure, causing small vapor bubbles to form within the liquid. This often happens on the suction side of the impeller where the pressure is lowest. As these vapor bubbles move to areas of higher pressure within the pump, they collapse violently. The implosion of these bubbles generates intense, localized micro-jets of liquid that impact the impeller surface. This repeated impact causes material erosion, gradually removing small particles from the impeller. Over time, this erosion creates pits and roughened surfaces on the impeller blades. This damage reduces the impeller's ability to efficiently pump coolant. The roughened surfaces disrupt the smooth flow of coolant, decreasing the pump's volumetric efficiency, which is its ability to move a specific volume of fluid per revolution. Furthermore, the implosions of cavitation bubbles create stress waves within the impeller material. These repeated stress cycles lead to fatigue cracking, eventually weakening the impeller and potentially causing it to fail structurally. The lifespan of the impeller is therefore shortened considerably. For instance, if a cooling system has air leaks that cause low pressure zones near the impeller, cavitation will occur more readily, quickly damaging the impeller and reducing the cooling system's overall performance.