13. Designing for Performance: The Impact of Blade Number and Pitch Angle Axial fan performance—measured by flow rate, static pressure, power consumption, and noise—is highly sensitive to the design parameters of the impeller, primarily the number of blades and the blade pitch angle[4]. The number of blades is a fundamental trade-off: increasing the number of blades improves the fan's ability to generate static pressure and often reduces tonal noise (by distributing the air disturbance more evenly), but it simultaneously adds weight, ac axail increases drag, and raises overall power consumption[4][5]. Simple propeller fans may have as few as two to four blades, optimized for moving air freely, while Vaneaxial ac fans may utilize many more to boost pressure in ducted systems[1].