Compared to a small consumer pc-case fan and similar, a turbofan is running at much higher Reynolds Number, which allows you to have more aggressive aerofoil profiles for generating lift. At small scales, aerofoils do not work better than flat plates (hence insects evolved thin wings), while at medium scales you need aerofoils that can keep a laminar flow attached. At high reynolds numbers, you have a similar effect as the dimpled golf ball keeping the air from detaching and recirculating early when it passes over the aerofoil of the fan blade, so you can give it an aggressive, high thrust shape.
Of course you cannot put a very high lift aerofoil near the blade tip as you would otherwise run into problems with locally supersonic flow creating lots of drag.
Wizatek t1_irqxbdr wrote
Reply to comment by GmeGoBrrr123 in TIL that passenger jet engines produce most of their thrust from fan at the front, not from the jet exhaust, and that this is called a high-bypass engine. by Rilot
Compared to a small consumer pc-case fan and similar, a turbofan is running at much higher Reynolds Number, which allows you to have more aggressive aerofoil profiles for generating lift. At small scales, aerofoils do not work better than flat plates (hence insects evolved thin wings), while at medium scales you need aerofoils that can keep a laminar flow attached. At high reynolds numbers, you have a similar effect as the dimpled golf ball keeping the air from detaching and recirculating early when it passes over the aerofoil of the fan blade, so you can give it an aggressive, high thrust shape.
Of course you cannot put a very high lift aerofoil near the blade tip as you would otherwise run into problems with locally supersonic flow creating lots of drag.